ShrimpManual text Apr - Aquaculture at Kentucky State ... text Apr.pdf · began in Florida in the 1970s. ... Levee style, earthen ponds, 1/2 to 3 surface acres in size, ... ShrimpManual

KSU’s Program of Distinction

ContentsIntroduction ......................................................................................................................... 2New Technological & Biological Developments .................................................................... 3Natural History .................................................................................................................... 3Broodstock and Hatchery & Nursery Production .................................................................. 5Pond Design and Water Supply ........................................................................................... 5Pond Preparation ................................................................................................................ 8Aeration and Water Circulation ............................................................................................ 9Water Quality .................................................................................................................... 12Aquatic Weed Prevention .................................................................................................. 19Stocking Juvenile Prawns .................................................................................................. 19Transport Methods ............................................................................................................ 21Substrate .......................................................................................................................... 21Feeds and Feeding............................................................................................................ 24Suppliers of Feed (Table 3) ............................................................................................... 27Harvesting and Yields ........................................................................................................ 28Factors Affecting Product Quality and Shelf Life ................................................................ 29Post-Harvest Handling ....................................................................................................... 29Live Markets ...................................................................................................................... 30Pond Bank Sales .............................................................................................................. 31Fresh Tail Market .............................................................................................................. 31Handling and Processing ................................................................................................... 31Processing Regulations ..................................................................................................... 32Economics ........................................................................................................................ 33Marketing in Kentucky ...................................................................................................... 37Dissolved Oxygen Chart .................................................................................................... 39pH Chart ............................................................................................................................ 41Equipment Vendors .................................................................................................... 43Suppliers of Postlarvae and Juveniles ................................................................................ 44

Published by the Kentucky State University Aquaculture ProgramCopyright 2002

It is the policy of Kentucky State University not to discriminate against any individual in its educational programs,activities or employment on the basis of race, color, national origin, sex, disability, veteran status, age, religion, or

marital status.

KSU Prawn Production Manual

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The Maylasian Freshwater PrawnThe Maylasian Freshwater PrawnThe Maylasian Freshwater PrawnThe Maylasian Freshwater PrawnThe Maylasian Freshwater Prawn has received the most attention from farmers has received the most attention from farmers has received the most attention from farmers has received the most attention from farmers has received the most attention from farmers because of its large size. because of its large size. because of its large size. because of its large size. because of its large size.

INTRODUCTIONThe United States is the world’s largest marketfor shrimp. Despite this fact, currently there isonly very limited production of shrimp andshrimp products within the U.S. In fact, theUnited States’ trade deficit in shrimp productsis in excess of $2 billion per year. This hascreated a great deal of interest in shrimpproduction within the U.S.

However, due to high land costs, strictenvironmental regulations along the coasts,and widespread disease concerns, theproduction of saltwater (penaeid) shrimp hasnot developed substantially in this country.These factors have increased interest in theproduction of freshwater shrimp or prawns inseveral areas of the United States.

Figure 2. Prawns do notappear to be susceptible tomost of the viral diseasesthat have devastated marineshrimp production.

Also, being primarily freshwater organisms,prawns can be produced farther inland, nearlarge urban markets. Freshwater prawns canproduce large individual sizes that are in highdemand in the market. In addition, freshwaterprawn production tends to be moreenvironmentally sustainable (compared withsaltwater shrimp production) because freshwaterprawns are more territorial in nature, and arestocked at lower densities.

However, this final trait also has been one of themajor constraints on prawn production.Compared with many saltwater species,production levels for freshwater prawns havebeen much lower. Also, at harvest, freshwaterprawns tend to have greater size variation thansaltwater shrimp, which negatively impactsmarketing. This is due to aggressive interactionsamong different morphotypes, especially males.To increase the commercial viability of prawnproduction, it is extremely important that

Figure 1. Farmers in Kentucky and other southeastern stateshave begun to show increasing interest in growingfreshwater prawns in ponds.

Aquaculture: KSU Program of Distinction

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production rates be increased, without sacrific-ing environmental sustainability, or size of theshrimp, and that the individual sizes offreshwater shrimp become more uniform.

NEW TECHNOLOGICAL AND BIOLOGICALDEVELOPMENTSInterest in prawn production has emerged atdifferent times in the U.S. over the last 25 years,although long-term, large-scale production hasyet to develop. Several technological andbiological developments have occurred that maymake prawn production in this country moreeconomically feasible. These include:1) Discovery that prawns can be raisedmuch farther north than previously thought, (andthat these conditions can actually increaseproduction).2) Development of size-grading proceduresprior to stocking which increases totalproduction and average weight.3) The addition of artificial substrate toponds which can allow higher stocking densitiesand production rates without sacrificing size.4) The use of increased feeding rateswhich can complement these technologies toallow them to achieve optimum production.

NATURAL HISTORYThis section on hatching and nursing prawns isto help the producer understand the animal.Most prawn growers will not hatch or nurse theirown seedstock.The freshwater prawn, also known as the giantriver or Malaysian prawn, is native to the tropicalIndo-Pacific region. Freshwater prawns belongto the family Palaemonidae which includes the

brackish and freshwater grass shrimp and thelarger river shrimp.

Most species that comprise this family requirebrackish water (dilute seawater) to complete theearly stages of their life cycle. Due to its largesize, relative to other freshwater shrimp, theMalaysian prawn has received the mostattention from farmers, investors andresearchers as a prospective culture animal inthe United States and other countries.

Although prawns have been grown to anindividual weight of ½ pound, the weight of farmraised prawns is usually 2 ½ ounces, or less. Inthe United States, commercial prawn culturebegan in Florida in the 1970s. During this time,attempts were made to start a prawn-farmingindustry in other tropical and subtropicalregions of the world. Between 1989 and 2000,prawn production worldwide increased over700%. Production is now valued above $1 billionannually. However, over 98% of productionoccurs in Asia. Recently, a freshwater prawnindustry has begun to develop in Kentucky andother southeastern states.

Figure 3. Freshwater prawns can be found along allcoastal areas of the Indo-Pacific region.


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Prawns breed and spawn in warm freshwater.Breeding takes place between a soft-shellfemale which has molted (shed) her shell and ahard-shell male. Using its long claws, the maleembraces the female and protects her for 1-2days until her shell hardens. The male depositssperm contained in a gelatinous mass betweenthe walking legs of the female.

A few hours after mating, the eggs are laid andfertilized. The female attaches the eggs to theunderside of her abdomen where they areincubated. Pleopods (paddle-like abdominalappendages) circulate water over the eggmass to provide oxygenated water and toremove debris.

At first, the egg mass or “sponge” is a brightyellow-orange color, but turns brown near thetime of hatching. A 1-oz. female may produce10,000 to 20,000 larvae 4-5 times a year.Mating typically will occur throughout the yearwhen water temperatures are above 70oF.Hatching occurs in approximately 3 weekswhen the water temperature is 80oF. The entirebrood hatches in 1 or 2 nights and the larvaeare dispersed by the female.

Newly hatched larvae must reach brackishwater with salinities of 10 to 14 parts perthousand (ppt) within 2 days, or they will notsurvive. At this stage, larvae swim upside downand tail first. They feed on zooplankton (microscopic animals), worms, and the larvaeof other aquatic organisms.

To reach the postlarval stage, the larvae mustundergo 11 molts in approximately 30 days.Postlarvae resemble adult prawns and areabout 0.3 - 0.4 inches in length. At this stage,postlarvae typically crawl along the bottom, butalso can swim in a forward direction right-sideup. Rapid backward movement is made bycontracting the abdominal (tail) muscles.

They begin migrating into freshwater 1 to 2weeks following metamorphosis. Postlarvae arecannibalistic and omnivorous. Insects, animaland plant material and even fecal matter fromother organisms may be included in their diet.Freshwater and a wide range of salinities canbe tolerated. As postlarvae reach the juvenilestage, their bodies become a blue or browncolor similar to adults. On average, it takes 95to 284 juvenile prawns to weigh 1 oz.

To reach the postlarval stage,To reach the postlarval stage,To reach the postlarval stage,To reach the postlarval stage,To reach the postlarval stage,the larvae must undergothe larvae must undergothe larvae must undergothe larvae must undergothe larvae must undergo11 molts in approximately 30 days.11 molts in approximately 30 days.11 molts in approximately 30 days.11 molts in approximately 30 days.11 molts in approximately 30 days.


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BROODSTOCKBroodstock prawns are collected during the fallharvest and are kept in tanks filled with water ator above 70oF throughout the winter. The ratio of2 to 3 males to 10 females is typically used.The total number of juveniles needed forstocking the following year will determine thenumber of broodstock collected. A 1-oz. femalemay contain about 10,000 to 20,000 eggs, andonly a fraction of these may survive through thenursed juvenile stage. Broodstock are fed eithera sinking trout or a marine shrimp feedsupplemented with fresh fish or beef liver.

HATCHERY & NURSERY PRODUCTIONThe hatchery and nursery procedures requiredto grow 30- to 60-day-old freshwater shrimpjuveniles for pond stocking are complex. Thesepractices require considerable training, laborand capital expense.

Experienced growers who wish to raise theirown seedstock are encouraged to trainthemselves with a small-scale hatchery and anursery pilot project before attempting largerscale production. Detailed hatchery and

nursery methods can be found in “ManagementPractices for Culture of Freshwater Prawns inTemperate Climates,” Mississippi StateUniversity, Bulletin 1030, Sept. 1995.

Prawn eggs are hatched from mid-February tomid-March. This is done in order to completethe 30-day hatchery and 30- to 60-day nurseryproduction phases by pond stocking time in lateMay or early June. Freshwater prawns,postlarvae and juveniles, will not tolerate watertemperatures below 60oF. Cold weatherrestricts the outdoor growing season to 4 to 7months in temperate climates. In theseclimates, indoor hatchery facilities are required.Inland production of postlarvae is restricted tobrackish water (10 to 14 ppt) recirculatingsystems which maintain water temperatures of81o to 85oF.

In the past, most U.S. producers purchasedjuvenile prawns from tropical hatcheries.Currently, indoor, recirculating hatcheries supplymost of the seedstock. A list of nursed juvenileand postlarvae suppliers is available from theKentucky State University Aquaculture Program(see listing in this manual - page 44 - or on theKSU Web site: www.ksuaquaculture.org).

POND DESIGN & WATER SUPPLYLevee style, earthen ponds, 1/2 to 3 surfaceacres in size, are well suited for freshwaterprawn production. Similar to ponds used togrow catfish, prawn ponds require road accessand electrical power (110v or 220v) for aerators.Since prawns are not harvested by complete

Figure 4. The brine shrimp, Artemia, are grown in cones andfed to the larvae.


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slopes of 3:1 will help discourage unwantedaquatic plant and algae growth as well asexcessive bank erosion.

Shallow ponds will store less oxygen-depletedwater than deeper ponds since their watervolume per unit of surface area is less. Withshallow ponds, there is less risk of a crop lossdue to a dissolved oxygen depletion caused bypond water “turnover.”

Interior Pond HarvestPrawns are harvested from ponds by drainingthe water down and concentrating the prawnsinto a catch basin (or large ditch), then removingthem with a small seine. The catch basinshould be about 10’ to 15’ wide with a lengthabout 2/3s the width of the pond.

Catch basin depth should be 18” to 24” deeperthan the pond bottom. A 1% to 2% slope of thepond bottom will allow water to drain through alowered stand pipe (drain pipe) located in thefloor of the catch basin. A drain pipe, 8” to 10”in diameter in a 1/2- to 1-acre pond, will facilitatefaster draining of the pond and reduce the laborrequired to harvest the prawns.

With shallow ponds,With shallow ponds,With shallow ponds,With shallow ponds,With shallow ponds,there is less risk of crop lossthere is less risk of crop lossthere is less risk of crop lossthere is less risk of crop lossthere is less risk of crop lossdue to dissolved oxygen depletion.due to dissolved oxygen depletion.due to dissolved oxygen depletion.due to dissolved oxygen depletion.due to dissolved oxygen depletion.

pond seining, a prawn pond may be square,round or irregular in shape.Figure 5.

Rectangular ponds may have a 2:1 length towidth ratio which allows good water circulation.

Figure 6.

Minimum and maximum depths of 3’ to 6’,respectively, should be used. Inside levee


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Figure 7.


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outside of the pond as they are flushed throughthe drain pipe. This method requiresconstruction of an additional collection or catchbasin outside the pond. The external collectionbasin should be constructed large enough tohold the entire harvest and should be designedto allow the pond water to flow through, yetretain the prawns in the collection basin. A netpen constructed of heavy seine material thatattaches over the drain pipe works well tocontain the prawns. This method of harvest alsorequires an additional source of water forpumping into the pond being harvested, toremove prawns stranded on the bottom or in thedrain pipe.

POND PREPARATIONThe use of well water reduces the likelihood ofintroducing unwanted fish and insects into thepond, all of which may prey upon newly stockedprawns. Ground water also is less likely tocontain pollutants. Well water sources thatprovide a minimum of 45 gallons per minute orgreater for each surface acre of pond surfacecan fill or flush a pond rapidly. Ponds should befilled 3 or more days prior to stocking juvenilesto inhibit the establishment of predacious,

Shallow watershed ponds can be used forprawn production provided fish and aquaticinsect populations are eliminated beforejuveniles are stocked. The pond should not bedeeper than 6’ to 8’ and must have a drain.Most watershed ponds do not have additionalground or surface water sources to fill themquickly, and populations of aquatic insects andfish are more likely to become established.

and treated to prevent unwanted fish andinsects from entering the pond.

Figure 9. Filter socks can be made from plastic windowscreen and stitched with monofilement fishing line. Shoeshops do an excellent job inexpensively.

Exterior Pond HarvestAnother harvest method is to collect the prawns

aquatic insect populations.Surface water from riversand streams may be usedto fill the pond 2 weeksprior to stocking, but allwater must be screened

The Use of Well WaterThe Use of Well WaterThe Use of Well WaterThe Use of Well WaterThe Use of Well Water reduces the likelihood of introducing reduces the likelihood of introducing reduces the likelihood of introducing reduces the likelihood of introducing reduces the likelihood of introducing unwanted insects into the pond. unwanted insects into the pond. unwanted insects into the pond. unwanted insects into the pond. unwanted insects into the pond.

Figure 10.

Figure 8.


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Predatory fish must be eradicated beforejuvenile prawns are stocked. Fish may beremoved by applying a 1 to 2 ppm solution of5% rotenone when water temperatures reach59o-70o F. This should not be done for 2 - 4weeks before stocking. (Rotenone can bepurchased from the Kentucky Department ofFish and Wildlife Resources (502-564-3400).

AERATION & WATER CIRCULATIONThe water in most prawn ponds is kept mixedby continuous or nightly aeration/circulationdevices. If the pond waters are not mixed,oxygen-depleted water may accumulate nearthe pond bottom due to thermal stratification.Stratification occurs during the summer whenwarmer, less dense water remains near thepond’s surface.

Figure 12. Continuous low dissolved oxygen levels in the bottom of the pond can result in shrimp mortality. Dissolvedoxygen testing is recommended in the early evening hours and before dawn.

may become cooler and deficient in dissolvedoxygen. Cool water is denser than warm waterand will remain near the pond bottom (Fig. 12).

Without adequate water circulation, much ofthe bottom habitat available to the prawns couldbecome unsuitable due to low temperaturesand the absence of dissolved oxygen. Sinceprawns are territorial, this reduction in availableliving space could lead to reduced survival,smaller shrimp, and reduced pond yields atharvest.

Figure 11. If freshwater prawns appear around the pond bank,especially in the morning or during the day, there is usually awater-quality problem.

Sunlight penetrates the upper water layer andphotosynthetic activity from phytoplankton(microscopic algae) releases oxygen into thewater. Deeper water receives less sunlight and


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A paddlewheel or aspirator pump-type aeratorA paddlewheel or aspirator pump-type aeratorA paddlewheel or aspirator pump-type aeratorA paddlewheel or aspirator pump-type aeratorA paddlewheel or aspirator pump-type aeratorplaced midway along the longest pond leveeplaced midway along the longest pond leveeplaced midway along the longest pond leveeplaced midway along the longest pond leveeplaced midway along the longest pond leveeis recommended for ponds without substrate.is recommended for ponds without substrate.is recommended for ponds without substrate.is recommended for ponds without substrate.is recommended for ponds without substrate.

Dissolved oxygen (D.O.) should not be allowedto drop below 3 ppm at any time. Low D.O.may cause prawns to crawl out of the ponds orcongregate at the pond edge during daylight.This will increase their vulnerability to predation. Prawns can tolerate temporary lowD.O. conditions; however, exposure should beavoided if possible. Dissolved oxygen metersshould be used to monitor D.O. in the earlyevening hours and before dawn. Full-timeaeration will reduce the risk of crop loss and

keep oxygen-rich water circulating throughoutthe pond. Since prawns are grown at lowerstocking densities and are not as mobile asfinfish, water circulation is likely to be asimportant as aeration.

A pond-side source of 220 volts or 110 volts ofelectricity should be available to supply watercirculation/aeration devices in the ponds. Inponds with no substrate, a paddlewheel oraspirator pump-type aerator placed midwayalong the longest pond levee is recommended.The aerator should be staked approximately6 feet out from the bank with its current flowingacross the width of the pond. This circulationpattern should send water flow to each end ofthe pond. Aerators rated at 1 to 4 horsepowerper surface acre are used.

There are many brands of aerators on themarket today. Vertical pump aerators are widely

Figure 14. Vertical pump aerator

Figure 13. Ponds without substrate should have theaerator midway along the longest levee, 6’ from thebank.

See page 14 for information andprices on water-quality testingequipment such as D.O. metersand pH meters.


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Propeller aspirators are widely used in themarine shrimp industry. They can be good inlarger ponds, range from 1 to 7 hp in size, andcirculate and destratify well. They function byinjecting air into the water. This results in lessevaporation compared with other areators. Abonus is that they don’t tend to cool the water asmuch on cold nights. Another consideration isthat propeller aspirators move a large volume ofwater, and require large anchoring devices tohold them in place.

Paddlewheel aerators are the most widely usedin the large-pond aquaculture industry. There

but can be superior in build and longevity.Additionally, parts are easy to obtain so downtime is usually short. Negative aspects includehigher initial costs, higher operating costs, andtheir greater weight makes them difficult toinstall and remove for repairs.

are two major types. “Taiwanese” paddlewheelsare constructed for use in the marine shrimpindustry. They are designed for constantcircuation and aeration, and are fairlyinexpensive and relatively light, makinginstallation easy. However, they are relativelyinefficient aerators and can be prone tomechanical problems if not properly maintained.Parts are sometimes hard to get.

Electric paddlewheels, such as those used inthe catfish industry, circulate and destratify well,and provide very efficient oxygen transfer. Theyare primarily designed for emergency aerationrather than constant circulation, and are moreexpensive than the Taiwanese paddlewheels,

Figure 15. Propeller aspirator

Fig. 16. Big John is an American-made paddlewheel.

Figure 17. Taiwanese paddlewheel

used for small ponds of 1/2 to 2 acres in size.The most efficient types lift the water about 18”and move as much water volume as possible.They are light and easy to handle, makinginstallation relatively easy. Also, beingdomestically produced, repair parts are easierto find. On the downside, vertical pump aeratorsdo not destratify or circulate well, and are onlyappropriate for small ponds.


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Juvenile prawns may be stocked atJuvenile prawns may be stocked atJuvenile prawns may be stocked atJuvenile prawns may be stocked atJuvenile prawns may be stocked ata rate of 24,000 to 28,000a rate of 24,000 to 28,000a rate of 24,000 to 28,000a rate of 24,000 to 28,000a rate of 24,000 to 28,000per acre with substrate added.per acre with substrate added.per acre with substrate added.per acre with substrate added.per acre with substrate added.

Paddlewheels driven by tractor PTOs aredesigned for emergency use only. They can bemoved from pond to pond as needed, and arefrequently used at larger farms with multipleponds where backup aerators are a necessity.

WATER QUALITY - Dissolved OxygenAdequate dissolved oxygen is necessary for thesurvival and growth of prawns. In aquacultureponds, prawns are stocked at a maximumdensity to assure profitability, and the requiredfeeding rate increases as stocking densitiesincrease. In short, morning dissolved oxygenconcentrations can decrease as feeding ratesincrease, making the use of mechanicalaerators essential.

Ideal D.O. concentrations in prawn ponds rangefrom 3 to 7 ppm. Prawns become stressedbelow 2 ppm D.O. and usually die below 1 ppm.

It is important that these minimum oxygenrequirements are maintained at the bottom ofthe pond. If a pond becomes stratified (layered),the bottom layer is typically lowest in oxygen.Aeration, therefore, must not only add oxygen tothe water but destratify the pond as well. Toensure that adequate D.O. concentrations anddestratification exist, aeration should be run 24

hours a day, 7 days a week. It is recommendedto begin aeration several weeks before stockingin order to condition the pond. D.O. and pHtesting should also begin at this time to monitor

Figure 18. PTO-driven paddlewheel

Figure 19. Graphs for D.O. charting are on page 39.


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the trends and cycles of the pond even beforethe prawn juveniles are stocked. Throughout thewhole season, D.O. should be recordedmorning and afternoon, and pH in the afternoon,and both should be graphed to better visualizetheir positive or negative trends.

Dissolved oxygen should be checked at the lowpoint before sunrise and high point (lateafternoon) daily. Oxygen-monitoring times of6:00 AM and 4:00 PM would be ideal. Avoid adelay in checking morning dissolved oxygenlevels - by mid to late morning, D.O.concentrations may have already risen tosatisfactory levels, and a possibly dangerouslylow D.O. reading that occurred at 5:00 in themorning may go undetected. In addition,checking D.O. at dusk and 2 hours later canallow one to predict how low D.O. will dropduring the night and when it will occur. If theprediction indicates that D.O. will fall to 1 ppmby 3:00 AM, you will know that additionalaeration may be necessary shortly aftermidnight.

The use of oxygen meters (page 14) isrecommended for all aquaculture venturesincluding prawn production. A reliable, durable,and waterproof D.O. meter is the YSI 550. Lessexpensive meters are available but may not beas accurate or durable. It is advisable to haveyour oxygen-testing equipment tested againstthe university’s equipment to make sureaccurate readings are being obtained.

Water Quality: pHPonds will, at times, have pH levels high enough

to stress (9.0) or kill (above 9.5) prawns. This isprimarily caused by metabolism of themicroscopic plants (phytoplankton) in the pond.Collectively these microscopic plants are knownas the pond’s “bloom.” As all plants do, duringthe daylight hours, the bloom consumes carbondioxide (CO2) through photosynthesis. SinceCO2 in water forms a weak acid (low pH), as itis removed by photosynthesis, the pond pHtends to rise during the day. After the sun goesdown, and photosynthesis ceases, pH falls asthe plants breath out CO2. This is a normalcycle of pH rising during the day and decreasingat night (similar to oxygen levels). How high andhow low pH will go is primarily controlled by twofactors:

1) how dense a phytoplankton bloom the pondhas (which is largely controlled by feeding rate)and2) how well the water is buffered. Bufferingcapacity is measured by testing the alkalinityand hardness of the water. Your County Agentor State Specialist can help you with these.

The best way to deal with high pH conditions inthe pond is to prevent them. If alkalinity and/orhardness are less than 50 ppm, it may beadvantageous to add agricultural lime to thepond at a rate of 1 to 2 tons/acre. This iseasiest to accomplish when the pond is empty.If a pond does develop pH levels greater than9.0, action must be taken. Prawn mortality canoccur if levels reach 9.5 to 10.

Specialists at Mississippi State University haverecommended adding 30 lbs/acre of cracked


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Prices vary and are subject to change. These prices are for planningpurposes only. This list of products is provided as a courtesy to readers,and does not necessarily imply a recommendation of the items.

Many Kentucky growers usea Hach FF1-A test kit.

Figure 20.


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corn every 2 weeks as needed. The intentionhere is for the starch (carbohydrate) in the cornto produce CO2 as it breaks down in the water,producing a weak acid (as described previously)and lowering pH. In Thailand, sugar is used asa purer and quicker dissolving source ofcarbohydrate. Ten to 20 pounds of sugar/acre/day can be added until pH drops. In NorthCarolina, gypsum has been recommended.When pH reaches 9.0, gypsum is added at 400lbs/acre. When pH reaches 9.5, a moreimmediate response is needed. Otherchemicals (such as alum) may be usedeffectively to lower pH levels, but a risk ofshocking prawns is involved. Contact anaquaculturist for advice specific to your pond.

The best way to deal with pH problems isprevention and preparedness. When buildingponds, after the clay is properly prepared with asheepsfoot roller, put some top-soil back in the

bottom. Add 1 to 2 tons of agricultural lime. It isrelatively cheap and won’t hurt. Add 500 to 600pounds of alfalfa hay or meal spread over thepond bottom prior to filling. Allow this to breakdown in the filled pond for 1 to 2 weeks prior tostocking. Always check pH everyday inmid-afternoon. Graph the pH so you cananticipate rising trends before they reach criticallevels. Have needed materials on-hand (sugarand gypsum). When you get a pH of 9.5 it is toolate to start looking for the things you need.

Water Quality: Ammonia

Figure 21. A pH grid is provided for your use on page 41.

In prawn production, pond ammonia isproduced from excreted wastes and feeddecomposition. The toxicity of total ammoniaincreases as pH and temperature increase.

Total ammonia should not exceed 1 ppm at apH of 9.0 or 2 ppm at a pH of 8.0. And toxic(un-ionized) ammonia should not surpass0.3 ppm. Reduced growth and even deathmay result with long-term exposure to highammonia levels.

High feeding rates are ultimately responsiblefor high ammonia levels. Ammonia can bekept reasonably low by not over-feeding, and ifhigh ammonia does occur, flushing with largeamounts of water sometimes helps. In certaincases, ponds can be fertilized to enhance thephytoplankton which can indirectly lower theammonia by consuming it as a nutrient.However, this may increase pH levels.Additionally, the proportion of toxic ammoniacan be reduced by keeping pH levels low.


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The determination of whether water is acid,neutral or base is defined by pH. Alkalinitymeasures the total amount of base present andis the indicator of the pond’s ability to resistlarge changes in pH (or buffering capacity).The concentration of total alkalinity should be nolower than 20 mg/L. Pond pH can swing widely,from 6 to 10, when alkalinity concentrations arebelow this level. Dramatic changes in pH cancause stress, poor growth and even death ofshrimp. The suggested range of total alkalinityconcentrations for prawn farming is 50-150 mg/L.

During the production season, prawn pondsshould be checked for ammonia once a week.

Calcium and magnesium are theCalcium and magnesium are theCalcium and magnesium are theCalcium and magnesium are theCalcium and magnesium are themost common sourcesmost common sourcesmost common sourcesmost common sourcesmost common sourcesof water hardness.of water hardness.of water hardness.of water hardness.of water hardness.

Water Quality: NitriteAmmonia and nitrite are waste products thatcome from prawn excretions and decomposedfeed. In the early years of prawn production inKentucky, stocking and feeding rates were lowenough that these waste products caused noproblem. The new, more aggressive rates nowmake it necessary for prawn growers to checknitrite twice a week.

Chloride ions in salt (sodium chloride) protectshrimp from high nitrite, so add a 50-pound bagof salt per acre-foot of pond volume at the startof the growing season and maintain thisconcentration throughout the whole season(adding salt after significant rain, etc.). A 1-acrepond averaging 4-feet deep would get four50-pound bags of salt. This equals 11 ppmchloride. More salt may be needed if nitritelevels rise above 3ppm.

Water Quality: Alkalinity and HardnessAlkalinity and hardness are both importantcomponents of water quality in prawn

hardness and total alkalinity when farmingshrimp.

production ponds. However, these two aspectsof water chemistry are commonly confused.The confusion relates to the term used to reportthese measures: • Total alkalinity indicates the quantity of basepresent in the water — bicarbonates,carbonates, phosphates and hydroxides.

• Hardness represents the overall concentrationof divalent salts present (calcium, magnesium,and iron) but does not identify which of theseelements is/are the source of hardness. It isimportant to recognize the difference between


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Hardness also is important for prawn culture.Calcium and magnesium are the most commonsources of water hardness. The criticalcomponent is the calcium concentration,referred to as “calcium hardness.” Calcium isessential in the biological processes of aquatic

animals. It is also important in the moltingprocess of shrimp and can affect the hardeningof the newly formed shell. It has been reportedthat freshwater prawns can tolerate a widerange of calcium hardness concentrations, butthe suggested range is from 50-150 mg/L.

Figure 22. LOOK AT THIS PRAWN CLOSELY. You may not see another one until the September harvest.Prawns will stay on the bottom of the pond if all is well.


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If aquatic weeds are present in the pond,If aquatic weeds are present in the pond,If aquatic weeds are present in the pond,If aquatic weeds are present in the pond,If aquatic weeds are present in the pond,the best approach is manual removal,the best approach is manual removal,the best approach is manual removal,the best approach is manual removal,the best approach is manual removal,using a rake.using a rake.using a rake.using a rake.using a rake.

Increasing Alkalinity andHardness in PondsIf alkalinity and hardness concentrations arebelow the suggested level, both can be increased by using agricultural limestone(calcite [CaCO3] or dolomite [CaMg(CaCO3)2].The use of hydrated lime [Ca(OH

2) or quick lime

(CaO) is not recommended because either ofthese compounds can cause the pH to rise veryrapidly to levels that are harmful to freshwaterprawns. The most reliable way to determinehow much agricultural limestone is required isto take soil samples from the pond bottom.Collect the samples the same way you wouldfor cropland and submit them to your countyextension agent or a university soils lab foranalysis. To get the correct recommendation,indicate that you want the liming requirementsuggested for “alfalfa production.” The amountof agricultural limestone needed for alfalfaproduction should meet the minimumrequirement for shrimp production. The best(and easiest) time to lime your pond is beforeyou fill it with water. Agricultural limestoneshould be distributed as evenly as possible overthe entire pond.

When pond alkalinity concentrations arebelow 50 mg/L, agricultural limestone can be

used to raise alkalinity and hardness. If totalalkalinity is above 50 mg/L, agricultural lime-stone will not increase hardness. In thissituation, or where hardness is not caused bycalcium, agricultural gypsum (calcium sulfate)can be used as an effective way to bringcalcium hardness to the desired concentrations.The addition of 5.5 lb of agricultural gypsum peracre-foot of water will raise calcium hardness(and total hardness, mg/L CaCO3) approxi-mately 1 mg/L. It is important to match calciumhardness with total alkalinity concentrations tohelp stabilize pond pH.

TemperatureThe optimum temperature range for prawns is77º – 90º F (25º – 32ºC). Although the averagesummer temperature range in Kentucky is atthe lower end of this range, there is anadvantage because the lower temperaturesdelay many of the prawns from reaching sexualmaturity, and more energy goes into growthrather than into sexual development.

Survival is shortened below 66º F (19º C) andabove 94º F (34º C), and death occurs quicklyat 55º F (13º C). In early October of 2000 and2001, several prawn ponds were lost to lowtemperatures just days before harvest, costing


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the farmers thousands of dollars in lost revenue.In Kentucky, prawns should be harvested by theend of September to make sure this does notrecur.

AQUATIC WEED PREVENTIONAquatic weeds are very difficult and expensiveto treat; the success rate for aquatic herbicidescan be as low as 50%. Prevention, by far, is thebest approach to aquatic weed control, and thefollowing steps can be taken to aid in thisprevention: • Keep the shallow end of ponds at least 3’deep. • Build the levees (dams) of the pond with a3:1 slope (to prevent extensive shallow areasalong the pond edge). • Maintain an adequate green phytoplanktonbloom to prevent clear water (Clear waterpermits sunlight penetration that can startaquatic weed growth).

STOCKING JUVENILE PRAWNSIn Kentucky, juvenile prawns are typicallystocked in ponds in late May or early June whenaverage pond temperatures consistently exceed68o F. In ponds without substrate, 16,000 to20,000 juvenile prawns are stocked per acre(3.34 juveniles/yd2) to obtain 1- to 1 1/2- oz.prawns by mid-September after approximately120 days.

A lack of reliable sources and the high cost ofjuvenile prawns have been a major industryconstraint. The cost to stock 1 acre with 16,000juvenile prawns which are 60 days pastpostlarvae is approximately $1,600. These

costs may not, but should, include packagingand transportation.

Due to the relatively short growing season intemperate climates such as Kentucky (100 -140days), it is important to stock juvenile prawns thatare large enough to ensure they will reach marketsize within that period. Prawns should be 0.25 g(about 1") when stocked. Prawns can reach thissize from postlarvae in 30 days if stocked at arelatively low density in nursery tanks 20 ft/2

(10 animals/gallon) or in 45-60 days if stocked athigher stocking densities such as 40/ft2 - 80/ft2

(20-40/gallon), respectively. Juvenile sizedepends on stocking density and duration innursery tanks as well as many environmentaland nutritional factors.

The actual size of the juvenile is the mostimportant variable; however, age may affect thenumber of reproductively mature (blue claws andegg carrying females). Older animals at stockingwill have a higher percentage of mature animalsat harvest, although they may not necessarily belarger.

Figure 23. Prawns should be acclimated to the pond waterbefore stocking.


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The stocking of juveniles, rather thanThe stocking of juveniles, rather thanThe stocking of juveniles, rather thanThe stocking of juveniles, rather thanThe stocking of juveniles, rather thansmaller postlarvae, generally reducessmaller postlarvae, generally reducessmaller postlarvae, generally reducessmaller postlarvae, generally reducessmaller postlarvae, generally reducesstocking mortality & increases yield.stocking mortality & increases yield.stocking mortality & increases yield.stocking mortality & increases yield.stocking mortality & increases yield.

Farmers should ensure that the stocker prawnsthey are purchasing have been in the nursery atleast 30 days. Prawns should weigh 0.5 - 1.0lb/1,000 animals (0.25 - 0.5 g) when stocked.Weigh some samples prior to stocking toensure prawns are of proper size.

To compensate for the short growout season intemperate climates, 30- to 60-day advanced-juvenile prawns (approximately 57 individualsper ounce) are stocked as opposed to thesmaller, less expensive postlarvae. Thispractice generally reduces stocking mortalityand increases yields. Without additional pondsubstrate, stocking densities in excess of20,000 juveniles per acre typically result insmaller prawns with less market value.

Size-grading juveniles into separate weightclasses prior to pond stocking has been shownto increase yields and reduce the number ofsmaller prawns of less value. Homogeneousprawn growth will likely result in increasedreturns. A small box grader with appropriatelyspaced bars (1” to 1.5”) can be used to gradethe prawns.

Before stocking, the pond water temperaturemust be at least 68oF (and rising). Juvenilesmust be temperature acclimated from thetransport water to that of the receiving pond.There should be no more than a 50 F differencein the temperatures of the hauling container andthe pond. Prawns can be acclimated bygradually replacing the transport water withpond water over a period of 20 to 30 minutes. Ifjuveniles are transported in plastic bagscontaining oxygen, the bags should be floated inthe pond for at least 5 minutes in the shade orduring periods of low sunlight. A quart of pondwater is added to the bags every 5 minutes toallow the prawns to adapt to the pond’s waterquality.

Figure 24. The use of a grader box should result ina more uniform harvest.


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Each 90’ row of substrate will be attached by

SUBSTRATEField trials are being conducted to determine ifthe addition of artificial pond substrate iseconomically feasible to increase prawn habitatand per-acre prawn yields. The addition ofsubstrate allows the stocking of more prawnsand may increase pond yields by 20% to 40%.Individual prawn size may also increase.

Plastic, high visibility, barrier, safety fencing maybe used as substrate. Vertical rows of fencingare anchored lengthwise within the pond. Withsubstrate, juveniles may be stocked at a rate of24,000 to 28,000 per acre. Increased wateraeration/circulation and feeding may berequired. With added substrate, aerators areplaced midway along the short side of the pond,so that water movement is parallel to thesubstrate.

TRANSPORT METHODSSuccessful prawn production starts with gettinghealthy animals into the growout pond. Prawnjuveniles should be stocked in hauling tanks atdensities no greater than 1/4 lb of prawns/gallonof transport water, for up to 6 hours. Higherstocking densities will result in the deteriorationof water quality and increased cannibalism intransport containers. If prawns are to betransported for greater periods of time thedensity should be reduced accordingly.

It is important to fill the transport container withcool (70o-72°F), clean, aerated water. Prawnsmust be gradually acclimated from the nurserytanks into the hauling water, which is usuallycooler. It also is very important to acclimate theprawns to pond water prior to pond stocking.Variations in pH, alkalinity, hardness and otherwater quality variables between transportcontainers and pond conditions affect thecondition and survival of prawn juveniles in theproduction pond. To acclimate prawns in ahauling tank, first drain 50% of water from thetank and add an equal amount of pond water.Allow 10-20 minutes for prawns to acclimatebefore stocking into the pond. If temperaturesare not within 2-3°F, repeat the procedure.

Substrate InstallationParallel rows of substrate should be spaced1’-2’ apart, and run lengthwise in the pond.

Figure 25. Prawns in tank trucks must be acclimatedbefore stocking.

Figure 26. Substrate should be tied firmly to posts using 5cable ties on each post. Posts should be about 45’ apart.


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First-time growers might wantFirst-time growers might wantFirst-time growers might wantFirst-time growers might wantFirst-time growers might wantto wait until the second yearto wait until the second yearto wait until the second yearto wait until the second yearto wait until the second yearto install substrate. to install substrate. to install substrate. to install substrate. to install substrate. Figure 27.


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cable ties to three posts. Although the barrierfencing (substrate) comes in 100’ lengths, it isbetter to set posts for only 90’ as many timesthe substrate sections come closer to 90’ than100’.

There should be a 6’ to 10’ empty space –substrate free — directly in front of the aerator,running the entire length of the pond. This willassure better water circulation.

Set all posts 3’ away from the inside of thecatch basin. Allowing for the 6’ to 10’ space inthe center of the pond, set the first post closestto the aerator, and walking toward the closestpond bank, place posts every 1’-2’. The lastpost set should be no closer than 3’ to the bank,on flat ground -- not on the slope of the levee.

Go back to the center of the pond, 3’ from thecatch basin, and again allowing for the 6’ to 10’center space, set posts every 1’-2’ as you moveto the other side of the pond. When finished,there is a single row of posts 3’ away from the

catch basin and 1’-2’ apart, stretching the entirewidth of the pond.

Stand at 1 of the 2 inside-most posts and run atape measure 45’ (lengthwise of pond) andplace the second post for that row at that point.Then measure another 45’ and place the thirdpost for that row. Follow this same procedurefor each row, as you move toward the pondbank. After completing the last row, whichshould not be closer than 3’ to the bank, repeatthis process on the other half of the pond.

“T” posts should be driven at least 12" into theground, or until secure enough that they do notsag under pressure. Starting in the deep end ofthe pond (near catch basin), and at the postclosest to the bank, attach the substrate to theposts using 5 cable ties per post.

Place the fencing material 6" to 12" off the pondbottom to allow prawns to walk unobstructedtoward the catch basin during harvest. Now, rollthe substrate to the second post (45’ away), pulltightly to get rid of any sag in the substrate,

Figure 28.


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then attach to the post. Repeat the same

process, attaching the substrate to the third post(90’ from the first post). All remaining rows ofsubstrate will be put up the same way. It shouldnot be necessary to add weight to the substrateto keep it from rising up, if it has been properlyattached to posts with cable ties.

Note: KSU personnel have found the installationof substrate to be faster and the rows to be moreuniform if flags are first positioned where postsare to be located, or another approach is to markthe post sites with a can of spray paint. Oncealigned properly, posts are driven at the flag or

paint locations.

FEEDS & FEEDINGIt is important to understand the feeding behaviorof prawns in order to efficiently provide feed ingrowout production. Prawns are bottom feedersthat find their feed mainly by smell, taste and feel,rather than eyesight.

Freshwater prawns are omnivorous scavengersthat feed on a variety of bottom organisms andorganic materials (detritus). The food habits ofprawns vary during different life stages. The

juveniles that are initially stocked in growoutponds eat all types of plant and animal matter;however, as they grow, their food habitschange and they become more carnivorous,feeding primarily on slow moving snails,worms and insects.

In pond production of freshwater prawns, thetotal weight of prawns in the pond is quite lowfor the first 30 to 40 days. Fertilizer materialscan be used during this period to increase theproduction of natural foods.

After the first 30 to 40 days, one should feed asinking feed that contains ingredients with alot of taste, such as fish meals and fish oils.Once food is located, it is chewed to asuitable particle size before being swallowed.This causes loss of nutrients from processedfeed to the water (i.e., leaching) and increases the need for pellet stability.

Because prawns are very slow eaters, andfeed more or less continuously, multiple dailyfeedings are desirable. Breakdown of the feedand leaching of nutrients can be minimizedthrough multiple daily feedings.

Prawns are bottom feedersPrawns are bottom feedersPrawns are bottom feedersPrawns are bottom feedersPrawns are bottom feedersthat use smell, taste and feelthat use smell, taste and feelthat use smell, taste and feelthat use smell, taste and feelthat use smell, taste and feelto find their food.to find their food.to find their food.to find their food.to find their food.


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Freshwater prawns are aggressive and willdistribute themselves evenly across the pondbottom. Unlike fish, prawns are territorial and donot swim great distances to get food. As aresult of this behavior, it is important to uniformlydistribute the feed over the entire pond area.

For small ponds (less than 1/2 acre) or wherelabor is relatively inexpensive, feeding is done byhand. In larger ponds, feeds are offered by theuse of boats or feed blowers.

Diets used for freshwater prawns range frominexpensive organic fertilizers, such as distillers’grains (less than $150 a ton), to expensive,highly refined 40% protein marine shrimp diets($500 or more per ton). As the poundage ofprawns increases in the pond, it is moreimportant to provide high quality, nutritionallycomplete diets.

Local feed mills can manufacture nutritionallycomplete pelleted feeds of 32% protein;however, steam pelleting generally onlyproduces a pellet that remains stable forapproximately 10 minutes. Commerciallyavailable marine shrimp diets are manufacturedthrough an extrusion process that increasespellet stability up to several hours.

Recent Feeding ResearchRecent research has shown little productionadvantage from using high-quality, expensivemarine shrimp diets compared to locallyproduced steam pelleted diets when prawns arefed twice daily. However, it appears the higherprotein diets do slightly increase the percentageof large high value animals (~ 5% increase) andmay be more important when prawns are fedonly once daily, or in newer ponds with relatively

little natural productivity.

Table A.Note: DDGS = dried distillers’ grains with solubles


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The feed chart on page 27 is based The feed chart on page 27 is based The feed chart on page 27 is based The feed chart on page 27 is based The feed chart on page 27 is based on a 1-acre pond. on a 1-acre pond. on a 1-acre pond. on a 1-acre pond. on a 1-acre pond.

Table 1 is a feed chart based on anassumed growth projection fromsampling data at KSU’s researchfacility. The feed chart is based on a1-acre pond. If you have a 1/2-acrepond - cut the daily ration in half. Itis best to divide the total dailyamount of feed into two feedings(½ daily ration, AM & PM). Withfull-time aeration of at least 1hp/acre,producers can feed as much as, butshould not exceed, 60 to 75 poundsper acre per day of a 32% to 45%protein feed by mid-August.

Table 2 is an alternative feedingchart showing the percentage ofbody weight the prawns shouldreceive daily, based on the totalbiomass density of the prawns in thepond.

To determine the biomass density itis necessary to seine the pond anddetermine an average weight bydividing the total weight of prawns

sampled by the total number of theprawns in the sample. Estimate totalbiomass by multiplying the averageweight by the number of prawns thatwere stocked into the pond.

Table 3 is a list of Kentucky-basedsuppliers of shrimp feed.

Figure 29. It is possible to feed shrimp by hand insmaller ponds of 1/2 acre or less. But larger pondsrequire feed distribution by a blower or boat.


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Feed Tables and Suppliers


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HARVESTING & YIELDSHarvestResearch conducted in South Carolina,Mississippi, and Kentucky has shown juvenileprawns will grow to a harvestable size of 1 to 2ounces in 100 to140 days. Research inKentucky has indicated cooler watertemperatures of 77oto 82oF may delay maturityin the female population which apparentlydetermines the rate of maturation of the maleprawns.

At lower water temperatures, dominant malesmature more slowly which reduces their abilityto suppress the growth of smaller males in thepond. As a result, the prawn population, as awhole, grows larger.

In Kentucky and other temperate climates, theselective harvest of large prawns may not bepractical due to the short growing season. In

some instances, small numbers of prawns mayalso be harvested with cast nets or baitedcrayfish traps.

Following harvest, prawns should be purged intanks of warm, clean water (chlorine free) for 5to 10 minutes. Purging will remove mud fromthe gill chambers and provide a cleaner producteither for live storage or processing. Moreinformation on post-harvest handling is givenlater in this manual.

YieldsPrawns are harvested in Kentucky throughSeptember but always before watertemperatures reach below 60oF. Overall,survival may vary between 60% to 80%. Yieldsfor mono-cultured prawns range from 500 to1800 pounds/acre/year throughout the world.

Multiple prawn crops in Taiwan are estimated toyield averages of 2,220 to 2,670 pounds/acre/year, while single crop production withoutadditional substrate averages approximately 600to 1,000 pounds/acre/year in Kentucky.Research experiments have shown the potentialto double pond yields by the addition ofsubstrate and more juveniles. In some cases,more feed and increased pond aeration may be

Figure 30. A standpipe screen should be placed on thepond drain pipe to catch prawns that may be washedthrough with the exhaust water.

In Kentucky, prawns must be harvestedIn Kentucky, prawns must be harvestedIn Kentucky, prawns must be harvestedIn Kentucky, prawns must be harvestedIn Kentucky, prawns must be harvestedin September, before water temps.in September, before water temps.in September, before water temps.in September, before water temps.in September, before water temps.drop below 60drop below 60drop below 60drop below 60drop below 6000000 F. F. F. F. F.


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required to support the increased prawnproduction.

FACTORS AFFECTING PRODUCT QUALITYAND SHELF LIFEWhen life ends, degradation begins. Not apleasant thought, but a fact nonetheless.However, a few major factors affect the rate atwhich a product loses quality. The processesthat must be addressed and controlled orslowed are primarily caused by bacteria andenzymes. One way to deal with bacteria is towash the prawns well. The muddy water from aprawn harvest contains bacteria that must beeffectively washed away as soon as possibleafter harvest.

The enzymes involved in product breakdownare primarily digestive enzymes located in theprawn’s head. When alive, these enzymeshelp the prawn digest its food. After death, theycan also “digest” the prawn’s tail meat if theprocess is not interrupted. These enzymesalso can cause the tail meat to become mushyin texture.

Freshwater prawns are much more susceptibleto this problem than marine shrimp, and lack ofunderstanding of how to deal with this hascaused serious marketing problems in the past.However, once one knows how to deal withthese enzymes, prawns can be stored as longor longer than marine shrimp.

To prevent both bacterial and enzymaticdegradation, prawns must either be kept alive orchilled. Lowering the temperature slows

bacterial growth and reduces enzyme activity. Ifthe prawns are not kept alive, chill themthoroughly and quickly.

The best way to prevent mushiness is to quicklyremove the head. However, some markets paypremium prices for whole animals.

Figure 31.

POST-HARVEST HANDLINGThe specifics of how freshwater prawns arehandled after harvest can vary based on thetype of market being addressed (e.g., live,whole-on-ice, frozen tails). Product quality canbe affected by how the animals are treatedduring harvest. Prawns should be removedfrom the ponds in a healthy state and as cleanas possible to achieve optimum product quality,no matter what the product form.

Prawns tolerate harvest conditions best whenwater temperatures are 70o- 72oF. Oxygenlevels should be monitored during pond drawdown because oxygen stress during harvestcan affect product quality later. Oxygen levelsbecome most critical when prawns areconcentrated in the catch basin. A small surfaceagitator-type aerator running in the basin canhelp to maintain adequate oxygen levels. Theability to flush clean oxygenated water into thecatch basin during harvest is also helpful.


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Prawns should be moved as quickly andefficiently as possible into “purge tanks.” Theseare tanks of clear, clean, aerated water adjacentto the pond where the animals can have themud washed off. It is helpful to have a series of4 to 8 tanks where the animals can be dippedand cleared of surface mud, while still in theharvest baskets. Then they can be moved toother tanks with cleaner water and allowed toswim freely, removing mud under the carapace.To accomplish initial cleaning as describedapproximately 2,000 to 3,000 gallons of clean,aerated water are needed for each 1,000pounds of shrimp to be harvested.

LIVE MARKETSThere is demand for live prawns, especially ingourmet and ethnic markets. However, prawnscan be difficult to hold and transport livebecause they are aggressive and territorial.Live prawns have been sold at wholesale pricesranging from $4.00 to $8.00 a pound, while finalretail prices of $10.00 to $22.00 a pound havebeen reported.

Live prawns must be marketed quickly beforecannibalism occurs in holding facilities. Ifprawns are to be picked up by a live hauler,pick-up should be scheduled at most 1 to 2

days after harvest. Tanks should be held at 70o

to 72oF and must not be allowed to drop below65oF during the night.

The tank should be well aerated and artificialsubstrate should be provided at a rate so thateach animal has about 1 square foot of surfacearea. Layers should be installed at least 4”apart to allow access for the prawns.

Figure 32.

Prawns that have recently molted or are aboutto molt are likely to be lost to cannibalism inholding tanks. This can account for up to 10%of the harvested crop. Such a loss has asignificant impact on profitability. Any animalswhich appear weak, soft-shelled, or approach-ing a molt, should not be placed in the holdingtanks but should be sold whole or on-ice,de-headed on-ice, or cooked and consumed.

Processed prawnsProcessed prawnsProcessed prawnsProcessed prawnsProcessed prawns yield about 50% edible tail meat. yield about 50% edible tail meat. yield about 50% edible tail meat. yield about 50% edible tail meat. yield about 50% edible tail meat.


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POND BANK SALESEven if animals are to be sold fresh on the farm,product quality is enhanced if those animals arequickly and humanely killed, their bodytemperatures lowered as far and as quickly aspossible, which is most efficiently accomplishedby chill-killing the animals in an ice bath.

This can be an additional tank of clean, clearwater with sufficient ice added to create a slurry.To chill-kill and thoroughly cool prawns willgenerally require about 1 to 1½ pounds of ice foreach pound of prawns harvested. Prawnsshould be left in the tank approximately 15-30minutes to allow sufficient chill time. Longertimes are not recommended because longexposure to the water can affect tail meattexture.

When placing prawns into the chill tank it ishelpful to contain them in baskets or a meshenclosure. If mixed in with the ice, weighingprawns for customers is complicated by thepresence of ice in the weigh basket.

Once prawns are thoroughly chilled, they can beplaced on drained ice for delivery or customerpick-up. Shaved ice is best. The insulatedcontainer should have a thick layer of ice on the

FRESH TAIL MARKETWhile certain markets will pay a premium forlive or whole product, other markets insist ontail-only product. Even for on-farm sales, manyindividuals desire to buy high quality, locallyproduced products but are not willing to processthe prawns. However, de-heading the prawns isextremely simple. For a tail market, all theharvest, washing, and chill-kill steps previouslydescribed apply. To de-head, simply grasp thehead in one hand, the tail in the other, and pulland twist.

HANDLING & PROCESSINGProcessed prawns yield approximately 50%edible tail meat. Retail prices received for tailmeat have been reported between $12.00 to$20.00 per pound. According to researchers inMississippi, more profits can be made by sellingthe prawns whole as opposed to de-headed.

Where headless shrimp or prawns are sold, thefreshwater prawn can be distinguished from thatof the marine shrimp (family Penaeidea). Thefreshwater prawn’s second tail or abdominalsegment (which is closest to the head) overlaps

bottom, with no prawns, to protect them fromcontacting the water. The container is thenpacked with alternating layers of prawns andice. However, the bottom layer and top layershould always be ice. Whole prawns can beheld on drained ice for 2 days. De-headedprawn tails can be held on drained ice 4 to 6days, although Mississippi researchers havereported as long as 12 days.

Figure 33. Pond-side sales can be profitable but are limited topersons living in the immediate area.


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the first and third segments, while in marineshrimp the second abdominal segment isoverlapped by the first.

PROCESSING REGULATIONSInspected food-processing facilities must beavailable if processed prawns are to be sold.Altered products, including headed, peeled orvalue added prawns will require processingfacilities which meet local health and/or FDAstandards. And a food safety plan called aHazard Analysis and Critical Control Points(HACCP) plan should be implemented. If theseproducts are sold to the end user or customer,an approved facility is needed, but a HACCPplan is not required.

If sold wholesale to a distributor, a restaurant, orvia interstate commerce, the processing facilitymust comply with HACCP regulations.Unaltered prawns, such as those sold live, orthose sold whole-on-ice are not covered byHACCP regulations, unless they are sold ininterstate commerce.

Decide how to market the prawnsDecide how to market the prawnsDecide how to market the prawnsDecide how to market the prawnsDecide how to market the prawnsbefore the harvest because that willbefore the harvest because that willbefore the harvest because that willbefore the harvest because that willbefore the harvest because that willdetermine how to handle them pond side.determine how to handle them pond side.determine how to handle them pond side.determine how to handle them pond side.determine how to handle them pond side.

Figure 34. Special attention should be paid to processing. AllHACCP regulations should be observed. One instance of badproduct being served can hurt the entire industry.

Figure 35. Post-harvest handling is important.Prawns should reach the processor in goodshape if the resulting product is to be tasty.


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ECONOMICSAs with any farm startup, the initial costsrequired for growing prawns can besubstantial; however, many farmers, mostlikely, will already have numerous items.

Of course, the farmer must have the land, andmay have to construct the pond, or perhaps,re-work a present pond. A 1-acre pond cancost up to $5,000 to build. We took $4,500 tobe our pond construction cost.

An aerator, water pump, dissolved oxygen orD.O. meter, and a water quality test kit will berequired. Some farmers may already have a

pickup truck, a riding mower, and a storageshed for prawn feed. Sometimes, holdingtanks can be borrowed or rented.

Investment ItemsItem Size/Time Cost

Land 1 acre $1,040

Pond 1acre/10yr 4,500

Aerator 1hp/3yrs 750

Waterpump 5hp/5yrs 542

D.O. Meter 5yrs 715

Water Qual. 1 yr 179Kit

Pickup 10 yrs 20,000

Riding 10 yrs 1,000mower

Weedeater 5 yrs 200

Storage 20 yrs 2,000shed

Harvest 10 yrs 60baskets

Holding tanks 10 yrs $400/ tank

Tracking expensesand time spentin prawn growoutare necessaryif you areto determineyour levelof productivityand profit or loss.


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Operating Expenses/Variable CostsOnce the pond design and preparation arecomplete, it’s time to think about stocking withjuveniles. Prices for juveniles vary from 10-12cents each in Kentucky. So putting in 16,000juveniles per acre, can cost about $1,600.Feed will cost about $500. The chart shows32% protein feed, about 100 lbs. per acre.

Other cost items include chemicals, electricityfor running the aerator, and gas for the pondpump, truck and mower. A permit is required,and don’t forget about maintenance. Also,calculate your cost for use of the telephone.

Harvesting Costs BreakdownHarvesting costs are an important part of prawnfarming. Costs include renting a trailer,obtaining oxygen, ice, packaging materials, andadvertisements. Harvesting costs should be

about $293.

Total operating expenses for a 1-acre pond- including harvesting costs - should beabout $3,095.

Variable Costs (16k/acre)Item Quantity Price CostJuveniles 16,000 0.10ea $1,600

32% Feed 1.49tons $342tn 510

Chemicals 1app. $61 61

Electricity 200

Pumping 1 time $20 20

Fuel 50 gals $1.50 75

Legal fees 1 permit $100 100

Maintenance 1 season $156 156

Telephone 4 months $20 80

Harvesting Costs Breakdown

Item Quantity Price CostTrailer rent 1 time $50 50

Oxygen 1 bottle $17 17

Ice 900 lbs 0.14 126

Packaging 50

Advertisements 50

Total Operating Costs- $3,095

The cost of juveniles for stockingThe cost of juveniles for stockingThe cost of juveniles for stockingThe cost of juveniles for stockingThe cost of juveniles for stocking will be the largest operating expense. will be the largest operating expense. will be the largest operating expense. will be the largest operating expense. will be the largest operating expense.


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Labor and ManagementLabor is a major part of prawn farming.Typically, a farmer spends about 1 to 1 1/2hours on a single-acre pond everyday infeeding, doing water quality tests, andequipment maintenance -- and also inmanaging the operation.

The chart estimate is a bit over $1,000 worth oflabor for 1 year. However, many farmersprovide the labor and management for free anddo not consider the labor costs in theaccounting expenses.

Non-Cash CostsNon-cash costs involve equipment depreciation,and interest on real estate and equipment.Annual depreciation considers the costs of thedeterioration of your equipment and ponds.Interest and depreciation combined should bebetween $1500 and $2000.

When all costs are added -labor and management are notconsidered - the total is just over$5,000 for growing 16,000freshwater prawns in a 1-acrepond.

Labor Requirements

Item Quantity Price CostStocking 2hr/acre $5.25 $10.50

Feed/Test/ 1hr/dyX107dy X$5.25= 562Maintenance

Daily Mgt. 1/2hr/dayX107X $8.00 = 428

Mow/Weed 2hr/wkX15wksX$5.25= 157.50

Total Labor Costs-$1,158

Non-Cash Costs

Annual Depreciation = $1,205

Annual Interest = 747 ========Total Non-Cash Costs $1,952


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Evaluating Breakeven PriceWhat is a breakdown price? It is the minimumprice at which a farmer needs to sell his/herprawns to cover costs.

Figure 36.

If the total output from a single-acre pond was800 lbs., the grower must sell the prawns for atleast $6.32 per lb. If more than 800 pounds areharvested, then the breakeven price is less. A1,000-lbs. harvest would take the breakevenprice to below $5.06 per pound.

Evaluating Breakeven Price

Total Operating Costs $3,095

Interest 747

Depreciation 1,205

Property Tax 9

__________________________TOTAL COSTS $5,056

Total Yield Breakeven price= Total Cost / Total Output______________________________________800 lbs/acre $6.32/ lb selling price900 lbs/acre $5.62/ lb

1,000 lbs/acre $5.06/ lb

Calculate your breakeven priceCalculate your breakeven priceCalculate your breakeven priceCalculate your breakeven priceCalculate your breakeven price in order to determine your profit margin. in order to determine your profit margin. in order to determine your profit margin. in order to determine your profit margin. in order to determine your profit margin.

Prawn Cycle

• Broodstock - Oct./April• Hatchery - March• Nursery - April/May• Growout - June/Sept.


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MARKETING IN KENTUCKYAs many prawn producers have discovered,pond-bank sales are an effective marketingtool. However, many farmers havesimultaneously realized that this market ishighly limited, primarily because its success isdependent on individual consumers havingenough motivation to drive to a farmer’s pondon harvest day to buy prawns at $6 to $10 perpound.

Many Kentuckians cannot afford to purchaseprawns at these prices, and even if they couldafford it, many are unwilling to drive to anunfamiliar farm that could be far frompopulation centers to buy this product.

Although it would be relatively easy forfarmers to sell prawns to wholesalers, currentwholesale prices ($4.30 /lb to $5.50 /lb) haveoften made this an unprofitable option. It isimperative for producers to discover wholesaleand/or retail markets that will pay $6 to $10 /lb,in order for prawn farming to be profitable. Afew individual entrepreneurial farmers haveexperienced success in selling prawns to

specialty restaurants that have clientele that arewilling to pay the prices necessary to makeprawns profitable for the restaurant. Anotherpossibility for retail sales exists in the many Kentucky festivals that are annually scheduled during the September prawn-harvestseason. These festivals often attract thousandsof visitors, who are looking to eat somethingunique.

Figure 37. The Freedom Freshwater Shrimp Festivalin Byrdstown, TN, featured several tents with shrimpprepared for every taste.

Figure 38. At the Byrdstown Festival, two chefs from NewOrleans used their special marinades before grilling Kentuckyand Tennessee freshwater prawns.

The interest level in prawns can be heightened ifprawns are prepared in a variety of methods(e.g., fried, scampi, Cajun-fried and prawngumbo). Profit can be enhanced by preparingprawn dishes that contain a few prawns andmany inexpensive side items such as rolls,fries, Cajun rice, and vegetables.


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(www.kyagr.com). Other options include usingtail meat of small males to produce value-addedproducts such as prawn Beignette, which is amixture of prawn and hushpuppy batter, friedand sold as finger food. This is similar to “crawfish poppers” produced with sub-marketcrawfish meat in Louisiana. However,developing these products will requiregovernment-approved processing facilities andmarketing ingenuity.

QUESTIONS If you have additional questions about the growing of prawns, contact your local Extension Agent or Kentucky State University’sAquaculture Research Center.

KSU Aquaculture Research Center103 Athletic RoadFrankfort, KY 40601502.597.8103www.ksuaquaculture.org

Small males are a marketing problem for pond-bank sales because customers are unwilling topay in excess of $6 /lb for stunted prawns.

Selling small males can be hazardous in retailmarkets that are hinged on product size, qualityand good producer reputation. Selling smallmales as bait at Kentucky’s bait shops mayprovide a viable marketing option. A list ofKentucky’s pay lakes and bait shops appears inthe Kentucky Aquaculture Directory publishedby the Kentucky Department of Agriculture

Renting a food booth can cost as little as $100per weekend and potential customers can beattracted by displaying aquariums of live prawnsand other Kentucky aquaculture species.Festival organizers often welcome participationof producers if they can provide an educationalexperience, in conjunction with food. Anaquarium, pamphlets and a video presentationabout prawn farming in Kentucky are severaleducational outlets that help consumersunderstand that freshwater prawns are anexotic species that is cultured under a quality-controlled environment. Information on thetiming, location and contact people forKentucky’s annual festivals are available online(www.tourky.com/tourky/festivalsevents.htm).

Consider joining with other growersConsider joining with other growersConsider joining with other growersConsider joining with other growersConsider joining with other growersin your area to sponsorin your area to sponsorin your area to sponsorin your area to sponsorin your area to sponsora shrimp festival in September.a shrimp festival in September.a shrimp festival in September.a shrimp festival in September.a shrimp festival in September.


39Copy this page 4 times for 4 months.

Table 4.


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This page for notes.This page for notes.This page for notes.This page for notes.This page for notes.


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Table 5.Copy twice for 4 months.


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NotesNotesNotesNotesNotes


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Equipment Vendors

Aqua Eco-Systems, Inc.Toll-Free: 877.FISH.STUFFax: 407.886.6787E-mail: [email protected]: www.aquaticeco.com1767 Benbow CourtApopka, FL 32703

Aquacenter, Inc.Toll-Free: 800.748.8921Fax: 662.378.2862Tech Assistance: 662.378.2861166 Seven Oaks Rd.Leland, MS 38756

Area, Inc.Phone: 305.248.4205Fax: 305.248.1756E-mail: [email protected]: www.areainc.comP.O. Box 901303Homestead, FL 33090-1303

Eagar, Inc.Toll-Free: 800.423.6249Phone: 801.292.9017Fax: 801.295.7569P.O. Box 540476N. Salt Lake, UT 84054

Southern Aquaculture Supply, IncToll-Free: 800.850.7274Fax: 870.265.4146E-mail: [email protected]: www.southernaquaculturesupply.comP.O. Box 326Lake Village, AR 71653

This list of vendors is provided as a courtesy to readers, and does not necessarily imply a recommendation of the companies.


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KSU Land GrantKSU Land GrantKSU Land GrantKSU Land GrantKSU Land GrantAquaculture Research CenterAquaculture Research CenterAquaculture Research CenterAquaculture Research CenterAquaculture Research Center103 Athletic Road103 Athletic Road103 Athletic Road103 Athletic Road103 Athletic RoadFrankfort, KY 40601Frankfort, KY 40601Frankfort, KY 40601Frankfort, KY 40601Frankfort, KY 40601502.597.8103 502.597.8103 502.597.8103 502.597.8103 502.597.8103 www.ksuaquaculture.org www.ksuaquaculture.org www.ksuaquaculture.org www.ksuaquaculture.org www.ksuaquaculture.org

Listing of Suppliers of Freshwater Prawn Postlarvae & Juveniles

Postlarvae & Juveniles Juveniles Only

Aquaculture of Texas, IncAttn: Craig Upstrom4141 Fort Worth HighwayWeatherford, TX 76087-8610817.594.4872

Thoroughbred Shrimp Co.8715 U.S. 421 N.Frankfort, KY 40601502.875.2461

Lauren FarmsAttn: Dolores & Steve Fratesi655 Napanee RoadLeland, MS 38756662.686.2894

Bluegrass Shrimp & Fish Co.Attn: Steve Price4425 Ernst Bridge RoadCovington, KY 41015859.371.2583

Freedom Freshwater Shrimp Co.Attn: Dan Cook or Doug ElderP.O. Box 39Byrdstown, TN 38549931.864.3005

Gregnon Farm, Inc.4780 Paris PikeMt. Sterling, KY 40353859.498.1698

(This listing of suppliers is provided as acourtesy and does not necessarily imply arecomendation of these companies.)


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Documents

ShrimpManual text Apr - Aquaculture at Kentucky State ... text Apr.pdf · began in Florida in the 1970s. ... Levee style, earthen ponds, 1/2 to 3 surface acres in size, ... ShrimpManual