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Fish Management in Aquaponics
William Lynch Jr. Millcreek Perch Farm, LLC (owner) Ohio State University Extension Program (retired)
Marriage of plant & fish production, hopefully with few martial problems! Plants depend on fish wastes for nearly all nutrient requirements, but also bacteria to transform ammonia / nitrite into nitrates readily usable by plants. Fish depend on bacteria to transform ammonia / nitrite into nitrates readily usable by plants so as to minimize nitrogen compounds returning to the fish production tanks.
Compatibility Is the species of choice compatible with the growth requirements of plants & bacteria.
Marketing Potential Markets – Need to Sell!
Availability Readily available sources in the quantities you need when you need them.
Feed & Heating Considerations Different costs for different species.
Bluegill sunfish Channel catfish Goldfish / koi Rainbow trout Tilapia Yellow perch
85 F 60 F 65 F 70 F 75 F 80 F 55 F
Warm weather plants Cool weather plants
85 F 60 F 65 F 70 F 75 F 80 F 55 F
Warm weather plants Cool weather plants
Nitrobacter Nitrosomonas
85 F 60 F 65 F 70 F 75 F 80 F 55 F
Warm weather plants Cool weather plants
Nitrobacter Nitrosomonas
Bluegill Channel catfish Goldfish / Koi Rainbow trout Tilapia Yellow perch
Best
8.5 6.0 6.5 7.0 7.5 8.0 5.5
Warm weather plants Cool weather plants
Nitrobacter Nitrosomonas
Bluegill Channel catfish Goldfish / Koi Rainbow trout Tilapia Yellow perch
Best
Stocking material for ponds & lakes is a multi-million dollar industry in the NCR.
Largemouth, sunfish, walleye, channel catfish. May be the easiest path to sell aquaponics fish. Goldfish (backyard ponds) & tilapia (algae control) demand increasing.
Food fish industry is considered by many to be stagnant at best in the NCR.
HAACP capable processors rare in the NCR, often not close to aquaponics operations. Largely trout, tilapia in decline. Yellow perch has not developed as most thought.
Species Stocking Food Fish*
Sunfish (Bluegill, Redear)
Channel Catfish
Goldfish / Koi
Rainbow trout
Tilapia
Yellow Perch
* = HAACP Requirements May Be Needed
Ease of Growing Rank Species Stocking Food Fish*
Sunfish (Bluegill, Redear)
Channel Catfish
Goldfish / Koi
Rainbow trout
Tilapia
Yellow Perch
* = HAACP Requirements May Be Needed
1
3
5
4
2
6
Largemouth bass Sunfish
Walleye Channel catfish
Rainbow trout
Source: 2012 USDA Census of Aquaculture
Hybrid Striped Bass
Species In Many
NCR States
1-Day Transport
Overnight Shipping
Sunfish Yes
Channel Catfish Yes
Goldfish / Koi Yes
Rainbow trout Yes
Tilapia Yes
Yellow Perch Yes
Choose between small (1-2 inch) or advanced fingerlings (3-4 or 4-5 inch). Amount of feed per day drastically different between sizes – impacts nutrients available to plants. Always buy feed-trained fingerlings – you would prefer not to have to feed train them yourself. If possible, buy the upper 50% percentile (length) produced by the hatchery. Do not buy the cheap runts, you will be sorry!
Know your state’s import regulations when purchasing fingerlings from out-of-state.
In Ohio, imported fish must be accompanied by health inspection certificate, disease testing results, and invoice.
If selling live fish to other states, know their import regulations.
State regulations do vary – check / inquire regularly Small aquaponics producers best served to sell in state, disease testing expensive.
http://www.ncrac.org/info/StateImportRegs/stateregsmain.htm
Species 40-50%
Protein $$$
32-38% Protein
$$
22-35% Protein
$
Summer Cooling
Winter Heating
Sunfish Yes Mod
Channel Catfish
Yes High
Goldfish/Koi Yes Mod
Rainbow Trout Yes Mod
Tilapia Yes High
Yellow Perch Yes Mod
Water temps no more than 3 F difference
pH no more than 0.5 difference
Salt at 1-3 ppt
Salt at 1 ppt 1 lb per 100
gallons
Tank density no more than 0.1 pounds of fingerlings per 1 gal. of water in static systems. If small biofilter on isolation tank, can go higher. Heavy aeration in no flow, isolation tank, monitor oxygen hourly until readings stabilize. Do not flow aquaponics system water thru isolation tank, defeats the purpose of isolation. Feed sparingly. Will ruin water quality unless equipped with small biofilter. Fish should remain in isolation for at least a week, preferably 2 weeks before being placed into the aquaponics system.
If isolation tank was a grow-out tank shut off from the aquaponics system, simply turn on valves to allow flow. If fish are to be moved from isolation tank to a separate grow-out tank ….
Be sure grow-out tank is nearly empty of water Move isolation tank water and fish to grow-out tank Slightly open valve to slowly add aquaponics system water very slowly until temps are equal. Once acclimated, open valves and begin feeding.
Stress is the leading cause of fish death in aquaculture Stress can be severe, causing death within minutes. Best example is a sudden low oxygen event. Chronic stress is longer term exposure to poor living conditions, causing impairment to the immune system. A chronically stressed fish is eventually a diseased fish and then soon a dead fish. Poor water quality is the leading cause of chronic stress.
A close aquaculture friend once told me : “A Successful Fish Culturist is not successful because he or she is a successful biologist, physiologist etc.”; “No, he or she is successful in large part because that person is a successful water quality and aquatic waste management specialist”; “If you successfully degrade nitrogenous wastes and uneaten food safely and therefore maintain excellent water quality, the fish will take care of themselves”.
Ammonia* (NH3)
Nitrite* (NO2)
Nitrate (NO3)
Fish Plants
Nitrosomonas Bacteria
Fish Wastes, Uneaten Feed
Nitrobacter Bacteria
Solids Removed
* Can be toxic to fish
Fish Feed 100% N 100% P
Retained in Tissues 30% N 32% P
Effluent 70% N 68% P
Solids 13% N 60-90% P
Dissolved 87% N 10-40% P
Source: Chris Hartleb, UW-Stevens Point
Species DO (mg/l)
Temp (F)
pH Unionized Ammonia
(mg/l)
Nitrite (mg/l)
Sunfish > 5 68-80 7-8.5 < 0.01 < 0.8
Channel Catfish
> 4 70-90 7-8 < 0.05 < 0.8
Goldfish/Koi > 5 65-75 6-8 < 0.08 < 0.6
Rainbow trout
> 6 50-64 6.5-8 < 0.01 < 0.8
Tilapia > 5 70-90 7-8 < 0.04 < 0.8
Yellow Perch > 5 70-76 7-9 < 0.02 < 1.0
Daily Water Temperature Dissolved Oxygen pH
2-3 Times per Week Ammonia Nitrite & Nitrate
Monthly Alkalinity / Hardness Carbon Dioxide
SRAC has fantastic factsheets on water quality!
Fish
Fish
Sump Plants
Plants
Plants
Plants
Solids Tank
Clarifier
= air stones
Oxygen / Temperature Ammonia / Nitrite / Nitrate
If temperature is too low . . . Turn up heaters
If oxygen too low in fish tanks . . . More air stones in fish tanks and possibly plant beds (bacteria in plant troughs need oxygen!) Consider an air stone in the sump
If nitrite / ammonia compounds are measurable in last plant trough . . . .
Reduce feed, as bacteria & plants not able to remove the compounds fast enough.
If nitrogen compounds non-detectable . . . Could feed fish more if desired for plants
Ad Libitum – feed as much as fish want in 15 minutes (also known as satiation feeding)
May be way in excess of what the bacteria /plant community can handle
Fixed ration per day – typically 1.5-3% tank fish biomass per day
Requires knowing numbers of fish in tank plus their average weight. Done by subsampling weekly. Labor intensive. May still be way in excess of what the bacteria / plant community can handle
Neither is well suited for aquaponics systems
Let the Ammonia / Nitrite / Nitrate Readings Guide Feeding Rate
Acceptable ammonia / nitrite levels at end of last plant trough – you can feed fish more. Vice versa.
Oxygenate Those Bacteria! Key to the ammonia to nitrite to nitrate cycle is a well oxygenated, prolific aerobic bacteria community.
Typically the first 6-10 weeks after an aquaponics system is brought online. And fish feeding has commenced. System contains very small, young plants requiring few nutrients at first but increases as plants grow. Nitrosomonas / nitrobacter community non-existent at first and slowly develops. Nearly 90% of fish problems & mortality occurs in this period.
Aquaponists overfeed their fish immediately after putting them into the grow-out tanks. The initial 6-10 week period often has wild swings in ammonia & nitrites as fish feeding begins. Elevated ammonia / nitrites will kill fish!
Monitor ammonia / nitrite levels daily at the end of last plant trough. 2-3 times per week thereafter once system stabilizes. Fish feeding is very little at first, often less than 0.1% tank biomass. As described earlier, let those readings in the last plant trough dictate feeding! Be patient!
