Aquaculture, 51 (1985) 49-63 Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands

49

CULTURE OF THE GUPPY, POECILIA RETICULATA, IN SINGAPORE

A.A. FERNANDO and V.P.E. PHANG

Department of Zoology, National University of Singapore, Kent Ridge, 0511 (Singapore)

(Accepted 17 September 1985)

ABSTRACT

Fernando, A.A. and Phang, V.P.E., 1985. Culture of the guppy, Poecilia reticulata, in Singapore. Aquaculture, 51: 49-63.

Singapore is known internationally as a breeding centre for the guppy, Poecilia re- ticulata. About 30 domesticated colour pattern and tail shape varieties are reared, mainly for export. The culture of these varieties at two rural and eight resettled farms is de- scribed. All farms are small family concerns. The resettled farms practise monoculture of guppies while the rural ones integrated farming. Guppies are reared in large, shallow, outdoor, cement tanks and nylon cage-nets suspended in ponds. Water in aquaria and ponds has salinities from 0.5 to 9.0%,, at neutral or alkaline pH of 7.0 to 8.3. The sizes and stocking densities of aquaria and nets vary within and between farms. In breed- ing tanks, a male to female sex ratio of 1:3, 1:4 or 1:lO is maintained. Newborn fry are collected daily and placed in nursery aquaria. After 3 weeks, these fry are sexed: young males are transferred to grow-out cement tanks, and females to grow-out cage- nets. Each farm has at least two ponds, one for water storage and the others for cage- net culture. Strains are cultured separately to maintain pure lines. Farmers improve colour patterns, size and fin shapes of the strains by continued mass selection. Four- to 6-month-old guppies are selected as brookstock and the rest which meet export quality are held in stocking aquaria and sold when demand arises.

Each farmer prepares his own formulated diet for the fish. Supplemental foods like live tubificiids, commercial dried fish flakes, or floating pellets may be given to adults, and water fleas to fry. The rural farms add pig manure to fertilise the tanks.

To remain viable in the future, farmers need to increase productivity by mechanising cleaning, draining, and filling tanks and ponds, feeding, and harvesting of the fish. This will cut down on labour and its increasing cost. Understanding the genetics of econ- omically important characters will also help farmers produce higher quality and more exotic strains.

INTRODUCTION

The wild-type guppy, Poecilia reticulata, is a polymorphic cyprinodont native to Trinidad, Barbados, Venezuela, Guyana, and parts of Brazil (Good- rich et al., 1934). The history of domestication and artificial selection of colour-pattern and tail-shape varieties of the guppy from wild populations is poorly documented, although it was reported to have started in the

0044-8486/85/$03.30 o 1985 Elsevier Science Publishers B.V.

50

CHOA CHU KANG

JOHORE STRAITS

I Km

103150E

Fig. 1. Map of Singapore to show the locations of rural guppy farms at Sembawang, Choa Chu Kang, and Yishun, and resettled farms at the Tampines Fish Breeding Centre (TFBC) at Tampines, and the Aquarium Fish Export Centre at Jalan Kayu.

early 1930s in the United States (Whitem, 1962). Some of the early mutant strains derived from domesticated wild stocks were spear-tails, pintails, swordtails, and veiltails. In 1941, some albino fish arose from an inbred line (Axelrod and Whiter-n, 1965). Wild populations of P. reticzduta were intro- duced into Singapore before 1937 for mosquito control (Herre, 1940), and are now well established in streams, monsoon drains, and canals (Johnson and Soong, 1963). From the late 1950s a number of colour-pattern and fin-shape varieties of guppy were developed by local guppy hobbyists through intensive artificial selection of spontaneous mutant genes affecting body and fin coloration, shape and size, followed by inbreeding and hybridization,

At present, 18 guppy farms are registered with the Primary Production Department of Singapore (PPD). Before 1979, farms rearing guppies were situated in various rural areas like Choa Chu Kang, Sembawang and Yishun, with the greatest concentration at Sembawang (Fig. 1). These rural farms practised integrated farming where, in addition to fish, poultry, pigs, vege- tables, fruits, and orchids were cultivated. From 1979 land in some rural districts was acquired by the authorities. Fish farms affected by land ac- quisition were given the option to resettle at Tampines Fish Breeding Centre (TFBC). These resettled farms at TFBC now practise monoculture of guppies.

To promote the ornamental fish industry, the PPD set up the Aquarium Fish Export Centre in Jalan Kayu in 1980, on land formerly used for

51

pig farming. This Export Centre has 30 plots, each 0.2 ha in size, for rental on long lease to exporters of ornamental fish. So far 20 aquarium fish exporters have been allotted sites at this Centre and five have completed their facilities and started operation (Singapore, 1984). The guppy is the predominant freshwater ornamental fish exported from Singapore (Singapore External Trade Statistics, 1963-1983). Other species of importance include the angel fish (Pterophyllum sculure), mollies (P. Zutipinna and P. sphenops), swordtails (Xiphophorus helleri), platies (X. mucukxtus), barbs, tetras, and gouramis .

There is little information on commercial culture of ornamental fish, and as Singapore is well known as a guppy breeding centre, the aim of this study is to describe culture activities there.

MATERIALS AND METHODS

Farm survey and water quality analysis

All guppy farms were visited but data from eight farms at the TFBC and two from Sembawang were included in this study. During visits to each farm the layout, the total number, size, and stocking densities of each type of aquarium and cage-net, the farm management, fish diets, and packaging procedures were recorded on survey forms designed by the authors. Salinity and temperature of water were measured 15-20 cm below the surface, with a salinometer (Yellow Springs Instrument Co., Model 33) with an attached thermometer. Readings were taken between 11.00 h and 12.00 h from five randomly-selected tanks for each type of aquarium and from five cage-nets. The pH of water from these tanks and cage-nets was determined with the Lovibond Comparator.

Feed composition

The ingredients of formulated diets for guppies were recorded. The food composition of these feeds as well as that of live and commercial foods was analysed. The moisture level was determined after heating over- night in a furnace at 105C. Crude fat and protein levels were determined by the Soxhlet and Kjeldahl methods, respectively. The ash content was determined after 48 h in a furnace at 55OC, and the nitrogen-free extract (NFE) was calculated after all the other values had been obtained, and subtracted from 100%.

RESULTS AND DISCUSSION

Farm layout and management

The eight farms at TFBC which practise monoculture of guppies range

52

TABLE 1

Number of aquaria, cage-nets, ponds, plots/pond, and average number of cage-nets/plot at two rural (A and B) and eight resettled farms (C-J)

Farm Ponds Plots/ Av. no. Farm area Aquaria Cage-nets pond for of

(ha) Water Cage- cage-nets cage-nets/ storage nets plot

A 1.618 1000 400 2 2 8 50 B 1.291 1293 360 3 2 8 45 C 0.563 508 90 1 1 2 45 D 0.615 420 192 1 4 6 32 E 0.676 1303 135 1 1 4 34 F 0.558 305 80 1 1 8 10 G 0.781 894 195 2 2 6 32 H 0.671 916 160 2 1 4 40 I 0.627 423 160 2 1 4 40 J 0.652 302 160 1 1 2 80

in size from 0.558 to 0.781 ha, with an average of 0.643 ha (Table 1). The two integrated farms at Sembawang were larger, with areas of 1.618 ha and 1.291 ha. These have, since 1979, been relocated to TFBC due to resettlement by the authorities. The layout of guppy-rearing facilities is similar in all farms in that the aquaria are aggregated in zones, although it was less orderly at the Sembawang farms (Fig. 2). The total number of tanks and cage-nets varied depending on the size of the farms (Table 1). The largest farm A, in Sembawang, had 1000 aquaria and 400 cage-nets while the smallest farm F, at TFBC has 305 aquaria and 80 cage-nets. The tanks are used for breeding, nurseries, grow-out of males, stocking and conditioning the fish. Each farm has at least two ponds, one for water storage and the others for cage-net culture of female guppies.

All farms are small family concerns. Food preparation, feeding, draining, cleaning, and filling tanks and ponds, transferring, grading, and packing fish for export are carried out in the mornings and late afternoons. In the afternoon, the workers manually separate the male and female juveniles, and sort adult fish for sale.

Aquaria culture

Large, shallow, cement tanks are used for breeding, grow-out of fry and young males and stocking. These tanks are built in rows end-to-end with two rows adjoining. These are separated from the next two rows by an aisle, 0.5-1.0 m wide (Fig. 2). Some farms use glass tanks for stocking and conditioning. The size of each type of tank depends on the discretion of the farmer, and the area and shape of the farm, and they are specially constructed for each farm. Thus there is variation in tank and cage-net

WATER STREAM

EMBANKMENT

l-----l RESIDENCE n I I

ENTRANCE

Fig. 2. Schematic diagram of the layout of a resettled guppy farm (farm G) at the Tamp- ines Fish Breeding Centre. Key: A = breeding tanks; B = nursery tanks; C = grow-out tanks; D = stocking tanks; E = multi-purpose shed; F = cage-nets in pond; G = conditioning area; P = motorised pump shed; SPl-10 = small cement ponds.

54

sizes both within and between farms (Table 2). No artificial aeration is used for guppy culture. The aquaria are devoid of aquatic plants and are partially covered by galvanized zinc roofing. About two-thirds of the water in the tanks is siphoned out and replaced every l-3 days. Every 3-4 months the cement aquaria are completely drained and a, powerful water jet is used to flush out the algae and dirt from the sides and bottom. Condi- tioning tanks are housed in sheds where packaging, sexing, sorting, and grading fish, and feed preparation are also carried out. These multi-purpose sheds are built close to the farm-house for convenience (Fig. 2). All the aquaria and ponds are covered with 2 mm2 nylon netting to exclude birds such as kingfisher, Ceryle rudis, and the cormorant, Phabcrocorux carbo sinensia.

1. Breeding aquaria Four- to 6-month-old males selected from grow-out tanks, and females

from cage-nets, are used as broodstock. The male to female ratio of breeders per tank varies between farms and may be 1:3, 1:4 or 1:lO. Each batch of broodstock is used to produce 4-6 broods before they are replaced by a younger batch. A single female can produce a brood every 26-28 days. The brood size ranges from 30 to 80 depending on the age and size of the females. A coconut leaf is placed in each breeding tank at nine farms, while a banana leaf is used in one farm, to provide shelter for the newborn fry as the adults are carnivorous.

Breeding tanks vary in length and width but have a uniform height of 0.46 m. The water level in these tanks is about 0.30 m. The stocking den- sities of breeding tanks are lower than those of nursery and grow-out tanks, and, depending on tank size, vary from 115 to 180 broodstock fish/m3 water (Table 2). The smallest of these tanks, 1.22 X 0.91 X 0.46 m with 0.33 m3 water, holds 40-50 breeders. The largest breeding tanks (2.13 X 1.83 X 0.46 m) with 1.17 m3 water contain 170-200 breeders. The practice of using high male to female ratios, together with the relatively high stocking densities in breeding tanks is to help to reduce the effects of inbreeding. Newborn fry are collected at least twice daily. Fry of the same variety are first placed temporarily together in a plastic or metal basin, which is left floating in one corner of a tank, and later in the day transferred to a nursery tank. Fry of different colour varieties are raised in separate nursery tanks.

2. Nursery aquaria The nursery aquaria are usually larger than the breeding aquaria (Table

2). Stocking densities range from 140 to 300 fry/m3 water. Fry of the same strain, with l-5 days age difference, are reared in a nursery tank for 17-21 days. By that time the juveniles are about 15 mm long and the sexes can be separated. The farmer uses a plastic Chinese soup spoon to scoop up the fry, one at time from a net suspended in a tank and scrutinises it. Fe-

TABLE 2

The sizes of tanks and cage-nets, and their stocking densities at the 10 farms

Aquaria Size (m) Vol. of water/ Stocking density Total no. of Length x width x height tank (m3/tank) (No. of fish/m fish/tank

water per tank)

Breeding 2.13 x 1.83 x 0.46 1.17 145-l 70 170-200 1.83 x 1.22 x 0.46 0.67 120-180 80-120 1.52 x 1.52 x 0.46 0.69 115-145 80-100 1.22 x 1.07 x 0.46 0.39 130-180 50- 70 1.22 x 0.91 x 0.46 0.33 120-150 40- 50

qursery 3.05 x 3.05 x 0.46 2.79 280-300 500-650 2.74 x 1.83 x 0.46 1.50 180-230 270-350 2.44 x 1.83 x 0.46 1.34 200-260 270-350 1.83 x 1.52 x 0.61 1.28 140-170 180-220 1.83 x 1.22 x 0.46 0.67 150-220 100-150 1.22 x 0.91 x 0.46 0.33 180-240 60- 80

Cage-nets 3.05 x 0.91 x 0.91 2.11 250-400 120-180 2.74 x 1.83 x 1.22 4.56 400-550 70-120 2.44 x 1.83 x 1.83 5.45 400-600 70-110

Grow-out 3.66 x 2.13 x 0.46 2.34 280-300 400-550 3.05 x 1.83 x 0.46 1.67 200-320 330-530 2.74 x 1.83 x 0.46 1.50 200-300 300-450 2.44 x 1.83 x 0.46 1.34 200-300 270400 2.13 x 1.83 x 0.46 1.17 160-180 190-210 2.13 x 1.37 x 0.46 0.88 160-180 140-145

Stocking 0.91 x 0.46 x 0.30 0.08 140-200 20- 30 0.61 x 0.46 x 0.30 0.06 100-150 15- 20

Conditioning 1.07 x 0.61 x 0.46 0.20 340-500 70-100 0.91 x 0.61 x 0.46 0.17 300-400 50- 70 0.91 x 0.46 x 0.46 0.13 220-320 30- 40

males are distinguished from males by the presence of the dark gravid spot at the urogenital opening. Young males also appear more streamlined than the females when viewed dorsally.

3. Grow-out aquaria After sexing, the male and female juveniles of a variety are reared in

separate grow-out tanks to prevent indiscriminate mating, maintain pure breeds, and to achieve faster growth (C.L. Lim, personal communication, 1980). When females are about 2 months old, they are transferred to cage- nets suspended in a pond where they are left to grow for another 2 months. In farm G, 10 small cement ponds (2 X 10 X 2 m) are used for grow-out of female guppies. Males remain in the grow-out aquaria till they are 3-4

56

months old. Of the different types of aquaria, those used for grow-out are the largest. The largest of these tanks measured 3.66 X 2.13 X 0.46 m and stocked 400-550 males or females. Stocking density shows con- siderable variation, from 160 to 320/tank (Table 2).

Broodstock are selected from 4-6 month-old fish in the grow-out aquaria and cage-nets. Breeder males are selected for large and streamlined body, large dorsal fin, fan or delta-shaped caudal fin, and, most importantly, for uniformity and vividness of colour patterns. Colour variants, if any, are selected at this stage and are greatly valued for production of new strains. Female breeders are chosen for large size, vigour, and expression of colour on tails.

The remaining males which meet export quality for uniform and bright colours, undamaged fins of appropriate shape and size, and freedom from disease are transferred to stocking tanks. Fewer females are sold because of their drab coloration. The rejects, mostly females, are sold to local a- quarium retailers where the better ones may be bought by fish hobbyists and the rest sold as live food for economically important carnivorous fish such as oscars (Astronotus sp.), marble goby (Oxyeleotris mapnoruta), and the golden dragon (Scleropages forrnosus).

4. Stocking aquaria Four- to 6-month-old males selected for sale are held in glass or cement

stocking tanks at densities of 100 to 200 males/m3 water. The different varieties are usually kept in separate stocking tanks. The stocking period varies from a few days to a few weeks. The turnover rate in the stocking tanks is higher from September to March when there is greater demand for ornamental fish from temperate countries of the northern hemisphere.

5. Conditioning aquaria When orders for fish are received, males from stocking tanks, and females

from cage-nets, are transferred to conditioning aquaria where they are held for l-3 days to ensure that they are disease-free before being packed. During this period the fish are not fed. Glass or cement conditioning tanks are small, for example 0.91 X 0.46 X 0.46 m (Table 2). Other containers, such as plastic or aluminium basins and Styrofoam boxes, may also be used. The stocking densities in these tanks are higher than for all other types of aquaria (220 to 500 fish/m3 water). For convenience, conditioning is carried out in multi-purpose sheds, where the fish are graded and packed.

Cage-net culture

In view of increasing demand for ornamental fish, coupled with heavy and rising capital investment costs (on land, construction of ponds, and cement aquaria), operating costs and severe labour shortage, a more ef- ficient and less expensive system for mass cultivation has become neces-

57

sary for long-term survival of the guppy industry. In response, each farm has at least one pond for cage-net culture (Table 1). This system of farming has long been practised in Indonesia, Cambodia and Thailand for food fish but has been introduced to Singapore only in recent years for ornamen- tal fish culture (Tay, 1977). In guppy farms 2-month-old females from grow- out aquaria are reared in cage-nets for 2 months.

The ponds for cage-nets are subdivided into 2-8 plots with vertical poles. Each plot contains at least two rows of nylon cage-nets which are partially submerged in water. Wooden planks serving as catwalks are con- structed between rows of cage-nets. These catwalks provide access to nets for feeding, stocking and harvesting the fish, as well as for installation and removal of nets. Cage-nets do not vary much in size between farms and usually have the following dimensions; 3.05 X 0.91 X 0.91 m, 2.74 X 1.83 X 1.22 m, or 2.44 X 1.83 X 1.83 m. The nets are fastened to the catwalks by nylon ropes and are weighted down by stones or sandbags. Each nylon cage-net costs about S$20 and lasts for about one year.

Cage-net culture has several advantages over aquarium culture; the capital outlay is lower, cost of food is reduced since the fish can feed on natural organisms in the water, water does not need frequent replacement, and conditions in the pond are more stable. However, in the tropics, the nets rapidly get clogged up with a thick layer of algal growth which is difficult to remove. This impedes the free flow of water between cages. As a result the nets have to be dismantled and removed from the pond monthly and the algae flushed out with a powerful jet of water.

Water storage ponds

Ponds for water storage and collection of rain water have earth bottoms with low, narrow embankments, and are not treated with chemicals nor fertilised after excavation. In some farms coconut trees are grown along the embankments to supply the leaves required for the breeding tanks. Size of ponds varies from 20 X 15 m to 40 X 15 m with depth of about 5 m, and they are usually shallower at the ends. Ponds are rectangular in shape for ease of operation, such as dredging, and removal of pest fish with seine-nets. The water storage ponds are excavated close to a brackish water stream or river estuary. Brackish water from these sources which is not filtered or chemically treated is pumped in to fill about l/3 of the ponds capacity. Fine-mesh screens over water inlets help to prevent enti&F of eggs and fry of pest fish such as Oreochromis mossambicus (tilapia), Gambusia affinis (mosquito fish), wild P. reticulata and P. sphenops (molly). Despite this measure, some pest fish are found in the ponds and have to be removed periodically.

Water q uatity

There were no significant differences in water quality between rural

58

and resettled farms. In a.ll farms, guppies were raised in outdoor tanks or cage-nets filled with brackish water diluted two-thirds with rain water, and salinities ranged from 0.5 to 9.0/ oo. As a euryhaline species, the guppy can also tolerate low salinity (0.0-3.0/oo) in conditioning tanks which are filled with standing tap water with addition of some rough salt. The pH of the water was in the neutral or alkaline range, with very little variation. Water temperatures ranged from 24 to 32C.

Feeds and feeding regime

In its natural habitat the guppy feeds on small invertebrates, aquatic insect larvae, algae, and other plant material (Nayudu, 1975; Dussault and Kramer, 1981). They are voracious and indiscrimate feeders. The farm- ers prepare formulated feeds for the guppies because of escalating prices of commercial dried fish foods and the unsuitability of some of them. Pre-

TABLE 3

Formulated diets and supplemental foods for guppy adults and fry

Farm Formulated diets

A

B

C

D

E

F

G

H

I

J

Skimmed milk powder, ground wheat bran, fish meal, or hard boiled egg yolk, or ground dried shrimp Skimmed milk powder, ground wheat bran, and minced beef or ground dried shrimp Skimmed milk powder, ground wheat bran, and fish meal Skimmed milk powder, ground oats, and wheat flour Buttermilk powder, ground wheat bran, and poultry starter crumbles Buttermilk powder, ground wheat bran, and fiih meal Buttermilk powder, wheat flour, and fish meal Skimmed milk powder, ground wheat bran, wheat flour, and fiih meal Skimmed milk powder, soya- bean flour, wheat flour, and fish meal Skimmed milk powder, ground wheat bran, and fish meal

Supplemental foods

Adults Fry

Nil Water fleas

Tubificiids

Tubificiids

Tubificiids Food flakes Tubificiids Floating pellets

Tubificiids Food flakes Tubificiids

Tubificiids

Tubificiids

Tubificiids

Water fleas

Water fleas

Nil

Water fleas

Nil

Nil

Nil

Nil

Nil

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pared diets from the 10 farms are quite similar (Table 3). Skimmed milk or buttermilk is used as the protein source. Ground wheat bran or wheat flour is used to supply carbohydrates and fibre, and to act as the binding agent. Usually equal proportions of these two ingredients are mixed together. To increase protein content, fish meal is included in the diets at 7 farms, minced beef or ground dried shrimps in farm B, and hard-boiled egg yolk or ground dried shrimps at farm A. Soyabean flour is included in the diet at farm I. No vitamin or mineral supplements are used. The fish feed is prepared each morning by mixing the ingredients together into a fine paste by gradual addition of water. It is then cooked or steamed in a large pan to form a semi-solid cake. When cooled, lumps of food are scooped by hand and fed to the fish.

The diets of adult fish at two farms are supplemented with imported food flakes (Wardley and Aqua&e) and at another with floating pellets from Japan (Table 3). In all farms except farm A, breeders are also given live Tubifex worms. The fry are fed with water fleas (Daphnia spp. and Moina spp.) in some farms, once a day at about 09.00 h. Formula feeds are given twice daily, at noon and 16.00-18.00 h till fry are about 3 weeks old (Table 4). Adults are fed 2-3 times daily, at about 09.00 h, 12.00 h, and 16.00-18.00 h. Live foods are obtained once every few days from farms which specialise in their culture.

In the two rural farms, pig manure was added as fertilizer to the cement aquaria and cage-net ponds to enhance the growth of natural food organisms. In these farms water hyacinth (Eichhornia crassipes) and water convolvulus (Ipomea aquatica) were grown in water storage ponds to be fed to pigs. Phang and Lee (1985) reported similar fertilization of ponds with chicken or pig manure for culture of sailfin mollies (P. Zutipinna) in Singapore.

TABLE 4

Frequency and times of feeding of the formulated diets, and supplemental foods of adult gunnies in 10 farms

Frequency and times of feeding of

Farm Formulated diet Supplemented foods

A I3 C D E F G H I J

Twice; 09.00 h, 17.00 h Nil Once; 12.00 h Occasionally; 09.00 h Once; 09.00 h Once; 09.00 h Twice; 12.00 h, 18.00 h Once; 09.00 h Twice; 10.00 h, 17.00 h Once; 09.00 h Twice; 12.00 h, 16.00 h Once; 09.00 h Twice; 12.00 h, 16.00 h Once; 10.00 h Twice; 10.00 h, 18.00 h Occasionally; 12.00 h Twice; 10.00 h, 18.00 h Once; 12.00 h Once; 12.00 h Occasionally; 09.00 h

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TABLE 5

Nutritional values of the formulated diets, and live and commercial food of the guppy (NFE: nitrogen free extract)

% % (% in dry matter) Moisture Dry matter Crude protein Crude fat NFE Ash

Formulated diets at farm

A 72.83 27.17 29.70 4.62 59.06 6.62

B 68.59 31.41 23.11 5.60 64.47 6.82

C 74.48 25.52 19.99 7.11 67.69 5.21

D 75.81 24.19 15.78 4.01 77.41 2.80

E 76.39 23.61 15.08 6.73 74.38 3.81

F 53.28 46.72 31.64 6.99 48.28 13.09

G 73.83 26.17 22.16 4.68 65.24 7.92

H 69.68 30.32 32.96 3.41 47.02 16.61

I 69.00 31.00 33.94 3.40 47.50 15.16

J 67.72 32.28 25.84 4.22 62.60 7.34

Commercial dried food Floating pellets 11.20 88.80 30.26 8.56 50.78 10.40

Food flakes (Wardley) 10.70 89.30 52.88 6.98 34.19 5.95

Live food Tubificiids 83.20 16.80 71.20 5.44 19.80 3.56

Water fleas 90.73 9.27 62.50 10.42 15.44 11.64

This method of integrated farming was introduced to South-East Asia by the early Chinese immigrants from the southeastern provinces of China, especially Kwangtung and Fukien (Chen and Sim, 1967). Prior to relocation to TFBC, the rural farms practised this traditional method of farming.

There is scant information on the nutrient requirements of the guppy. A recent study by Chua (1983) showed that 6- to l&week-old female guppies (variety Tuxedo) required a 30% protein level for optimal growth and food conversion efficiency. Crude protein levels of formulated diets ranged from 15.08 to 33.94% of dry matter (Table 5). The protein levels in formulated feeds at farms D and E were low because they did not include fish meal or other high protein ingredients (Table 3). In contrast, live foods and commercial food flakes contain more than 50% protein. Due to high costs, only breeders and fry are given live food. The nitrogen free extract (NFE) values of formulated feeds were high (47.02 to 77.41%). Fat levels in live, commercial, and formulated feeds were comparable, ranging from 3.40 to 10.42/00. Live foods had the highest moisture content, 83.20%

. . . . for tublficnds and 90.73% for water fleas; flakes and pellets had the lowest values, 10.70% and 11.20% respectively; while formulated feeds had inter- mediate values of 53.28 to 76.39%.

Packing for export

For export by air freight, 4-6-month-old guppies after conditioning are placed in plastic bags, 67 X 25 cm or 70 X 25 cm, Each bag contains 2-3 1 of standing tap water with rock salt added, bringing salinities to

61

8-12/oo. The stocking density per bag is 50-75 fish/l water. The anti- biotic tetracycline at concentrations of about 200 mg/l water is added. The bags are inflated with 4-6 1 of oxygen and the open end tied tightly with rubber bands. These bags of fish are delivered by pick-up lorry to exporters or they may be collected by brokers who in turn supply to ex- porters. The fish are repacked by the exporters into oxygenated plastic bags, placed in Styrofoam boxes (38 X 38 X 26 cm), and delivered to the airport.

Marketing

Ornamental fish exported from Singapore are locally produced or im- ported from countries such as Thailand, Indonesia, Malaysia, Hong Kong, Taiwan, and Japan (Singapore External Trade Statistics, 1963-1983). Total export increased from S$O.7 million in 1963 to about S$31 million in 1983 (Table 6). The bulk of the rise in export is due to increases in local production although imports have also been increasing but at a slower rate. Of the 200 species of ornamental fish exported from Singapore, the guppy is the most important. The major international export markets for freshwater ornamental fish are the United States, Federal Republic of Germany, United Kingdom, France, and Italy. Prices of guppies depend on the variety, time of the year, sex and size. The demand rises from Sep- tember to March during the autumn and winter months of the northern hemisphere, with the peak from December to February. More males are sold and they fetch higher prices because of their attractive colours and varied fin shapes. Males of common local varieties (like Red Tail, Blue Tail and Tuxedo) are sold for S$0.20-0,40/fish. Males of newer varieties (like Neon and Rainbow) may fetch up to S$l/fish. Females are much cheaper, selling for S$O.O5-0.12 each. Smaller fish cost less,

TABLE 6

Quantity and value (thousand S$) of the import and export of ornamental fish for the years 1963 to 1983, at 4-yearly intervals. Statistics obtained from the Singapore External Trade Statistics 1963- 1983 (Jan. to Dec.)

Import (CIF)

Quantity Value

Domestic export Export (FOB) (FOB)

Quantity Value Quantity Value

1963 24 644.51 287 264 n.a. 59 750 80 782 174 1967 125 491.80 1 385 190 n.a. 214 238.96 2 671 106 1971 357 909.66 1855 529 na. 687 045.61 7 591 172 1975 335 339 3 084 472 1 777 063 13 292 936 1 243 310 14 413 070 1979 709 453 6 115 809 1402 216 33 690 551 1441 308 34 538 300 1983 504 018 6 840 000 1 555 606 30 538 000 1588 066 30 846 000

not available Freight On Board

CIF Cost + Insurance + Freight S$ Singapore dollar Export Domestic export + reexport of imported fish.

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CONCLUSION

Although Singapore is only 629.2 km2 in area, her strategic geographic location and excellent network of air connections with major world markets, coupled with the ingenuity and dedication of farmers, have led to the growth and success of the ornamental fish industry. In recent years the acute land shortage has been keenly felt because of the need for land for other purposes such as industrial development, public housing and amenities. As a result many farms have been affected by land acquisition. Some farms, including A and B, have been resettled from their scattered rural locations to the TFBC. However, a number of smaller ones have given up operations because of insufficient capital and expertise to start anew. Other difficulties faced by guppy farmers are shortage and high cost of labour, partly due to the tendency for young workers to shun employment in the agricultural sector for work in the city and factories. In order for these farms to remain viable they need to mechanise cleaning, draining and filling tanks and ponds, and feeding and harvesting the fish, so as to reduce manpower costs. In guppy farming the most laborious and time-consuming task is that of sexing juveniles individually. A possible way of overcoming this problem is to produce all-male progeny by genetic or hormonal methods, which has been successfully carried out for tilapia (Guerrero, 1979; Hulata et al., 1981).

The ingredients of the formula feeds for guppies are imported, and the cost is increasing. To reduce costs, farmers could select for fast growing fish using cheaper alternative food sources. Understanding the genetics of economically important characters of the guppy valued by fish hobbyists would help to produce new and more exotic varieties. This is essential to sustain the interests of guppy fanciers.

ACKNOWLEDGEMENTS

The authors thank the guppy farmers, especially Mr. and Mrs. Tony Toh, Mr. and Mrs. C.L. Lim, Mr. B.C. Leow, and Mr. B.K. Toh, for their cooperation and help. We appreciate the generous assistance of Mr. George Tay, Head, Freshwater Fisheries Laborato_ry, Sembawang Field Experimental Station, Primary Production Department. We thank Mrs. J. Mui for typing the manuscript, Mr. K.J. Goh for special assistance, Mr. H.K. Yip for pre- paring the prints for the figures, Mrs. O.Y. Yap for drawing Fig. 1, and Mr. W.L. Chua for the food analyses. This work was funded by a grant, RP 3/76, from the National University of Singapore to V.P.E. Phang.

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