CARP BREEDING AND HATCHERY MANAGEMENT
by-DR RAJESH KUMAR SINGH ,JAMSHEDPUR,JHARKHAND, INDIA, 9431309542,rajeshsinghvet@gmail.com
COMMON CARP BREEDING:
Common carp can breed easily in natural pond conditions. Therefore induced breeding is not required. In common carp breeding, one female and two male brooders are required to form a set. The weight of the two male brooders and one female brooder should be equal for ensuring total breeding and fertilization. The selected brooders have to be released in a breeding happa or a small tank, which will serve as a space for breeding and fertilization. Since common carp eggs are adhesive, the breeding happa/tank should be provided with sufficient water plants, preferably water hyacinth. Alternatively, when common carp are reared in a pond, kakaban can be constructed with the help of bamboo poles as borders and water hyacinth spread evenly inside the kakaban. These water plants serve as substratum for the eggs to stick on their roots or inner surface. The brooders are then removed or the water plants containing the attached eggs are transferred and distributed in a series of happas where rigorous aeration is provided with the help of showers. The eggs hatch out in 2-3 days depending on the water temperature. After hatching, the hatchlings have to be kept in the happas till the yolk sac is absorbed and then transferred to nursery ponds.
Hatching time is temperature dependent. Usually hatching takes about 15 – 18 hours at temperature range of 26-31°C with D.O. not less than 5 mg/l. At lower temperature, the hatching time is considerably longer. The hatchlings pass out through the mesh of the inner mosquito netting happa to the outer happa. When hatching is completed, the inner happa with egg shells is removed and the hatchlings are left undisturbed in the outer happa for three days till the yoke sac is completely absorbed and hatchlings, now called spawns become ready for stocking in nursery ponds. The hatching technique described above has, however, several draw backs and large scale mortality due to natural hazards like. a. Sudden change in water temperature. b. Development of algal bloom. c. Depletion of D.O. level. d. Pressure of predatory crustaceans, etc. With a view to improve hatching technique and reduce mortality of hatchlings, various modern technique mentioned earlier i.e. the Chinese hatchery system are now being used.
COLLECTION OF FERTILISED EGGS AND HATCHING:
Eggs should not be collected or transferred out of breeding enclosure until they are water hardened. In traditional breeding enclosure, the bottom corners of the breeding Happa are untied first and lifted slowly from the back to the other open end of the Happa. The brood fishes are skillfully pushed back and carefully removed by scoop nets without disturbing much of the eggs. The happa with the eggs is then lifted above water and transferred to plastic buckets by a graduated known capacity plastic mug of 1 litre capacity. From the plastic buckets, eggs are collected with the help of a mug and spread uniformly at the rate of 3-4 liters of eggs in double -walled hatching happa fixed in ponds free from algal bloom or in a circular tank with continuous water supply. The outer Happa is made of thick cloth or very fine meshed nylon cloth while the inner one is made of round mashed mosquito netting cotton/nylon cloth.
Dimension of breeding and hatching Happa.
Type of Happa Dimension(m) L B H Specification
Breeding Happa 2.5 1.25 1.0 Closed from all sides except at the opening with tying arrangement. Thick cotton/ nylon cloth.
Hatching Happa Outer 1.8 1.0 1.0 Upper side completely open. Thick Meshed nylon/ cotton cloth. Inner 1.5 0.8 0.5 Upper side completely open. Round Mosquito netting of cotton/ nylon cloth.
The number of eggs to be spread in each happa depends on the size of the eggs of the species concerned. The following table will be helpful in deciding the amount of eggs to be incubated in a happa.
Quantity of eggs of carp species to be incubated in each happa
Species No. of eggs/l (Approx) Amount of eggs in liter/happa.
Catla 22,000 – 25,000 4.0
Rohu 28,000 – 30,000 3.0
Mrigal 26,000 – 30,000 3.0
S. Carp 22,000 – 25,000 4.0
C. Carp 22,000 – 25,000 4.0
What is Induce breeding?
Induce breeding means making the fish release eggs and milt artificially through some inducing agents when they will not do so naturally. Induce breeding is done when the pond condition cannot be made to encourage natural spawning or when the fish are not ready to breed when the farmer wants them to spawn. Except Common carp all the three Indian and two Chinese major carps viz. Catla, Rohu, Mrigal, Silver carp and Grass carp, cultivated under composite fish culture do not breed in pond condition although they attain full gonadal maturity. Therefore, to make these carps breed in artificial enclosure, the hypophysial hormone extracted from the pituitary of donor fish are injected into the sexually matured fish under favorable water and climate condition during the monsoon season. This process of artificial administrating of pituitary hormone into mature fish is also commonly known as Hypophysation. In India, first success of induced spawning by hypophysation of IMC was achieved by Chanduri and Alikunhi (1957). Subsequently, Silver carp and Grass carp were also breed in 1962 (Alikunhi et.al. 1963). This outstanding success in induced spawning of Asiatic major carp has revolutionized carp culture production through commercialization of carp seed production. Fecundity:- It is the number of ripening ova in the female ovary prior to spawning period. Rate of fecundity of many fishes provides information on population, production and stock recruitment.
BROODER MAINTENANCE AND CARE:
An adequate brood stock is an essential prerequisite for successful induced breeding programme. Brood fish means the male and female fish, which are used for breeding. Only after the brood fish reach sexual maturity, they can be induced to spawn. Therefore, stocking and rearing of brood fish is very important. The brood fish can be grown in the farm or collected from outside source and reared in proper brood fish ponds. The stocking rate for brood fish is usually2,000-2500 kg/ha preferably 2-3 years old healthy male and female carps should be selected and reared in well prepared ponds of 0.2 to 0.5 ha with minimum water depth of about 1.5 m. The stocking density should be kept at a relatively lower level ranging between 1500- 2000 kg/ha. Ponds management should be done. Supplementary feed consisting of 1:1 oil cake and bran mixture should be applied daily at the rate of 1-3% body wt. The addition of 15-20% fishmeal, vitamins and mineral mixture to the conventional feed gives better results. For grass carp, aquatic weeds, grass, leaves are to be provided at the rate of 20- 25% of their body wt. The fishes should be periodically netted and examined for their stage of maturity and state of health. This rearing period normally last for 4- 5 months. It is estimated that for a target production of about 10 million spawn (6 million spawns of IMC and 4 million spawns of silver and grass carps) about 750 kgs of brood stock (300 kg of IMC and 450 kg of silver and grass carp) comprising both male and female in a ratio of 1:1 by weight and 2:1 by number are required.
Estrous and spawning:
Under the influence of pituitary extract or hormones, breeding takes place within 4-6 hours after the second injection. The brood fish generally begin to chase each other excitedly. This phenomenon is called Estrous. This chasing can be apprehended soon after seeing the irregular ripples that appear on the water surface. The abdomen and caudal fin of female intensely constrict and eggs flow out like a jet. At the same time the male come close to female and discharge milt to fertilize the eggs.
STRIPPING METHOD:
This method is also commonly used in induced-breeding of fish. It has the advantage of producing high percentage of fertilization. The administration of hormone such as pituitary gland (P.G.) extracts or the synthetic hormone like ovaprim, ovatide etc. are the same except that the brooders have to be stripped for the eggs and milt. This is done after 4- 6 hours of administering the dose when the male starts chasing the female in the brooder’s tank. One person holds the female fish above the egg tray/pan and another person gently presses the belly of the female fish just below the lateral line. The gentle stripping is continued till the egg oozes out or comes out from the vent of the spawner which is collected in the tray. Immediately following the same method, the milt is stripped out from the male and spread over the eggs in the tray with some amount of water. The eggs and milt are mixed properly with the help of bird’s feather or gently tilting the tray and allowed it to stand for 10-15 minutes for better fertilization. Then it is transferred to hundies (aluminium vessel), half-filled with water for water hardening for 30 – 45 minutes and kept in a shaded place. The fertilized and water hardened eggs swells like small pearls of 3.5 – 5.5 mm in diameter and are transparent in colour, while dead or unfertilized ones appears opaque under naked eye which can be partially segregated. The water hardened eggs does not rapture or spoil easily and is ready to transfer in the Circular Hatchery or Hatching Happa for further hatching.
PITUITARY GLAND OF MAJOR CARP AND ITS COLLECTION:
The pituitary gland or hypophysis of Asiatic major carps is a small pear shaped, whitish soft body, situated on the ventral side of the brain below hypothalamus. The quantum of hormones in the pituitary varies with the season and maturation stages of the fish and hence the degree of success achieved in induced spawning depends very much upon the condition of the pituitary gland of donor fish. Thus, the pituitary glands for the induced spawning programme should preferably be collected from the freshly killed fully matured specimen of both the sexes during May/June when the potency of the gland remains at its peak.
COLLECTION OF PITUITARY GLAND:
To collect pituitary gland, the head of the fish may remain with the body or it may be cut apart. Following methods are used to collect the gland from the fish: a. Use a due knife or wood hammer. b. Hold the fish near the head with one hand. c. Hit the fish near above the eyes at the point where the skull begin. This will kill the fish. d. Make sure to hit straight and up a little. A solid hit should dislodge the skull. e. Slit the skin around the front and sides of the skull then lift up the top of the skull and fold it back as if it were a hinge. The brain is attached to the top of the skull, by folding it back, the underside of the brain is exposed. The pituitary gland is located in the middle part of the underside of the brain. Excess fluid in the cavity are soaked using a bloating cloth. The gland is collected with the help of forceps.
PRESERVATION AND STORAGE OF PITUITARY GLAND:
Freshly collected glands have been found to be the best for the induced breeding purpose. But when we need a large number of glands to take up breeding on a commercial scale, large collection and preservation of the glands from the fish markets are necessary. The most common method of preservation of pituitary glands is preservation in absolute alcohol. The gland preserved in alcohol is removed and after an interval of 24 hours they are dried, weighed and transferred to dark colored phial containing fresh absolute alcohol. Alcohol dehydrates and defattens the glands. The phials are then kept at room temperature or in a refrigerator. Acetone, which is also a dehydrating, and defattening agent is said to give better result. Here, the glands collected and preserved in fresh acetone are placed in a refrigerator and after two days the glands are dried using filter papers and weighed and replaced in phial with fresh acetone. In both methods, the phials should be kept airtight in refrigerator or deep freezer. The potency of the gland preserve in alcohol remain up to 2 to 5 years where as the potency of the gland preserved in acetone claim to be retain from 2 to 10 years.
Breeding tanks of circular shape are of Chinese design. A convenient size of a circular breeding tank is 2m diameter and 1m deep which would hold about 1800 liter of water. A breeding tank may also be rectangular in shape.
The size of the breeding tank varies with the brooder holding capacity. For holding 4-6 brooder, weighing 3-6 kg each, the size of breeding tank may be 2.5mx1.5mx1.0m.
TABLE 5: Size of breeding Tank
No. of Brooder Kg/body weight Size of breeding Tank
4 – 6 3 – 6 2.5m x 1.5m x 1.0m
8 – 10 3 – 6 4.0m x 2.0m x 1.0m
Common essential feature of a circular breeding tank:
I. Continuous supply of clear clean and well oxygenated water of optimum temperature.
II. The tank bottom should slope towards the outlet, which is located at the centre of the circular tank.
III. The water inlet is set at a 40° angle target to the tank wall in order to impart a circular motion to the water.
IV. The outlet which is installed in the centre of the tank bottom is fitted with a straight pipe and a screen is provided covering the perforation and serve to maintain the water level in the tank and as a passage for collection of eggs. It is possible for a circular breeding tank to function also as an egg incubator, hatching tank or fry rearing tank by installing extras facilities like air diffusion or air blower.
BREEDING SET:
The Spawners should be grouped into several sets. Each set should consists of both female and male Spawners in the ratio of 1:2 and approximately 1:1 in weight i.e one female of 3 kgs is paired with two male each weighing 1.5 kg. The selected breeding sets can be kept either in happas or in modern breeding enclosures.
a. Traditional spawning enclosure:
In India ,the immediate environment for induce breeding is considered to be the breeding Happa inside which the injected brood fish of both the sexes consisting of one female and two male are released to spawn. A breeding Happa is a rectangular cloth container ( 2.5 x 1.5 x 1.0m ) closed from all sides except an opening on one side with tying arrangements. This Happa is fixed in shallow regions of ponds with the help of bamboo poles in such a way that two third (2/3) of it are submerged in the water. The Happa should be fixed at a depth where it is easily accessible to the aqua culturist. Happas is fixed in bamboo poles in such a way that ¾ parts of it remain immersed in the water without touching the pond bottom mud. Usually 20-30 cm above the bottom mud, the four lower sides of the Happa is fixed in respective bamboo pole. Similarly ¼ part of the net (usually 15-20 cm) which is above the pond water with its four sides fixed with respective bamboo poles tightly so as to keep the breeding Happa in right condition. The cloth usually used is strong, fine meshed mosquito net type. The mesh size of net cloth should be such that the ovarian eggs do not pass out of the breeding Happa.
b. Modern breeding enclosure:
Nowadays, modern hatcheries called Chinese hatchery or Ecohatchery are operated for mass production of carp seeds. The essential component of a modern hatcheries are
I. Storage tank (Brooder holding tanks) for conditioning of brooders before breeding operation.
II. Over-head tank for storing water to run the hatchery.
III. Circular breeding tank provided with showers for simulating rain conditions. The induced brooders are kept in this tank for spawning.
IV. Egg collection chamber for collecting the fertilized eggs.
V. Incubation or hatching circular tanks which is double walled with mesh net covered outside the inner wall for hatching the fertilized eggs. Larval rearing tanks for conditioning the spawn before releasing into the nursery.
PREPARATION OF PITIUTARY EXTRACT:
Pituitary extract is normally prepared just before administration as such extracts cannot be kept long. Fish pituitary extract is prepared in distilled waterglycerine media at a concentration of 40mg of gland for every ml of media. a. Use 2 to 3 mg of dried pituitary gland for every kg of body wt. donor and match the weight of the donor and recipient i.e. two 1.5 kg donor will be required for a 3 kg recipient.
b. The required quantity of gland are taken out of the phials and the alcohol allowed to evaporate
c. Place the known quantity of gland into the mortar.
d. Grind the pituitary with the help of pestle or a test tube with distilled water equal to ¹/3 of the total volume of extract until it turns into a pulpy mass.
e. Place the test tube into the centrifuge.
f. Centrifuge the gland for 5 minutes.
g. The supernatant fluid is drawn into a hypodermic syringe and is made ready for injecting the brooders. TABLE 1: Pituitary Gland
Dose (mg/kg body wt).
Female (♀) Male (♂)
1 st dose 2 nd dose
1. Catla 2 – 4 5 – 10 2-4
2. Rohu 2 – 4 5 – 10 2-4
3. Mrigal 2 – 4 5 – 10 2-4
4. Silver carp 2 – 4 5 – 10 2-4
5. Grass carp 2 – 4 5 – 10 2-4
It is to be noted that when pituitary gland is used, the females are given two injections at an interval of 4-6 hours while the males are given only one injection at the time of the second injection to the females. The dose of the pituitary may be slightly increased or decreased depending on the local climatic condition, potency of the gland and the response of the Spawners.
SYNTHETIC HORMONE FOR INDUCED BREEDING:
The commonly used synthetic hormones which are available in the market are namely: “Ovaprim”, “Ovapal” and “Ovatide”. Advantages:
1) A single dose can be injected/administered simultaneously in male and female.
2) Accuracy of prescribed dose and time saving.
3) Easily injected.
4) Effective even under adverse climatic condition.
5) Can be stored at room temperature (20 – 30 oC).
6) Produces increased no. of eggs through complete spawning with high fertilization and hatching percentage.
7) Produces healthy fish seed with high potential for excellent growth.
8) Sacrificing of brood fish for pituitary gland is avoided.
Synthetic Hormones
Species Dose ( ml/kg body wt).
Female (♀) Male (♂)
1. Catla 0.3 – 0.5 0.1 – 0.2
2. Rohu 0.3 – 0.5 0.1 – 0.2
3. Mrigal 0.3 – 0.5 0.1 – 0.2
4. Silver carp 0.4 – 0.5 0.1 – 0.2
5. Grass carp 0.4 – 0.5 0.1 – 0.2
In case of synthetic hormones, both males and females are injected only once at the same time.
SELECTION OF BROODERS FOR SPAWNING:
Usually after the onset of the monsoon, when there is an accumulative of fresh rain water in the ponds and fall in atmosphere temperature, the breeding programme in taken up. The southwest monsoon is the normal breeding season for the Asiatic carps and usually extends from May to September. TABLE 3:
Differentiation of Male and Female Brooder
Male Brooder
1. The abdomen is not bulging. When the abdomen near the vent region is pressed slightly, milt oozes out easily.
2. They are also characterized by the roughness of their pectoral fins when touched from the inside
3. The vent is not pinkish and with pointed papillae.
Female Brooder
1. The abdomen is soft and bulging. When the female brooder is kept ventrally upward the belly on both the sides are swollen due to ripe ovary. Eggs ooze out when slightly pressed.
2. The inside of pectoral fins are smooth to touch.
3. The vent is pinkish and with almost rounded papillae. In Grass carp, care should be taken because the bulging of belly may be due to excessive feeding and in Catla, due to considerable deposition of abnormal fats within the body cavity.
METHOD OF INJECTION:
Usually two methods are adopted for injecting the brooder fish. They are intramuscular and intraperitonial. a.Intramuscular Injection: This method is very effective and convenient. The intramuscular injection is given on the dorso-lateral muscle towards the caudal peduncle avoiding the lateral line. As two split doses are given for carp spawning, the pricks are made on either sides (right and left) alternatively to reduce the physical strain to fishes. The needle is inserted under the scale parallel to the body of the fish and then turned to 45˚ angle to pierce quickly the muscle and inject the fluid. b.Intraperitonial Injection: In this method, a brood fish is placed over a foam rubber cushion laterally. In carps, there are soft region at the base of pectoral or pelvic fin through which injection needle is inserted. Point the syringe needle towards the head at an angle of 45° to the body’s longitudinal axis and insert the needle. A 2ml hypodermic syringe with 0.1ml graduation is convenient for use. The needle specified for different body weight of fish is given below.
Specification of needle and procedure for administration
Needle Size Body weight of Fish (kg)
1.B.H.No. 22 1-3
2. B.H.No. 19 >3
3. B.H.No. 24 <1
DOSE AND FREQUENCIES OF INJECTION:
The induced breeding work is generally taken up on a cool and cloudy days when the water temperature is around 25-30 °C. In the case of pituitary gland, it is always convenient to apply the first injection between 16.00-17.00 hrs and the second injection after 4-6 hours of the first injection i.e. between 20-23 hrs. After the first injection to the female spawner, both male and female of the set are released in the breeding happa or the breeding enclosure. At the time of the second injection, both males and females are injected as per prescribed doses and released back in the breeding happa or breeding enclosure.
IDENTIFICATION OF FERTILIZED EGGS OF SOME CULTURED CARPS
Nature Diameter (mm) Shape Colour Species
1. Non-floating/ (i) 5.3-6.5 round Yoke light red Catla Non- Adhesive (ii) 5.5 -do- Brownish Mrigal (iii) 5.0 -do- Reddish Rohu (iv) 4.2 – 4.7 -do- Pale bluish Silver
2. Pelagic/ Non (v) 4.5 – 5.5 -do- Golden brown Grass Adhesive
3. 3. Demersal/ Adhesive (vi)1 – 2.0 -do- Yoke yellow C. carp. to light brown, occasionally colorless
Eco-hatchery-circular spawning pool
It consists of circular cement pools (8 m diameter) with 50 cubic metres of water holding capacity. The bottom of the pool slopes to the centre, where there is an outlet pipe (10 cm diameter) leading to the incubation pond (egg collection chamber). The wall of the spawning pool is provided with diagonally fitted inlet pipes at an angle of 45o for circulation of water creating artificial riverine conditions. After circular pool is filled with water, about 80 kg of females and 80 kg of males are released into the pool. When the breeders start coming up to the surface, the valves are opened so that a circular current is created. The speed of water current is maintained at about 30 m/min. The yield of 10 million eggs per breeding operation is usually achieved.
Eco-hatchery Incubation pool
As spawning goes on in the spawning pool, the fertilised eggs are led into the incubation pool (3 m diameter - double walled circular pool, with inner wall of regulated mesh permitting outflow of water) where water at a regulated speed enters through the duck mouth valves fitted on the floor of the outer chamber. The speed of the water is regulated @2.5 litre/sec in the initial stage and then reduced to 2.0 l/sec when movement of embryo inside the eggs starts. After hatching, the speed is again increased to 3.0-3.5 l/sec. and the hatchlings are allowed to remain there for about 3 days till the yolk sac is absorbed.
Rearing of seed-hatchling to fry/fingerling stage
Presently two techniques are practiced.
• Rearing in earthen ponds at the fish farm.
• Two phased seed rearing - Phase one inside the hatchery building and phase two rearing in earthen pond at fish farm.
Rearing in earthen ponds at fish farm up to fry stage
From the hatchling receiving ponds (nursery ponds), the weeds are removed. Unwanted fishes are removed using mahua oil cake containing 4-6% saponin at the rate of 2000-2500 kg/ha meters. Lime is applied @ 250-300 kg/ha. for neutralizing acidity and helping mineralisation of organic matter. Manuring of ponds with cow dung @5000kg/ha is done about 15 days before the anticipated date of stocking by broadcasting all over the pond (dose of cow dung is doubled when Mahua oil cake is not used). Aquatic insects are controlled. Suitability of water is tested. Thereafter ponds are stocked with about 3-4 days old spawn usually in the morning hours. The moderate rate of stocking may be 25-30 lakhs/ha.
Supplementary Feed
A mixture of finely powdered groundnut/mustard oil cake and rice bran/polish, in equal proportion by weight is supplied to the fry. Cobalt chloride or Manganese sulphate (trace elements) @ 0.01 mg/day/spawn may be added to the feed. Addition of yeast increases survival of fry. Feed may be broadcast all over the pond commencing from the day of stocking. Feeding may be stopped one day earlier to the harvesting. The generally recommended feeding schedule is given below.
Feeding strategy for fry of Indian major carps
Period Rate of feeding per day Approximate quantity per one lakh of spawn/day
1st to 5th day 4 times the initial total weight of spawn stocked 0.56 kg
6th to 12th day 8 times the initial weight of spawn stocked 1.12 kg
13th & 14th day No feeding
(Source: Food and Agriculture Organisation)
Feeding should not to be suspended in adverse ecological conditions.
Chinese Fish hatchery
• The location of a Chinese Hatchery should ideally be on a sloping high land for economical construction. If sloping land is available the floor level of the spawn collection tank should be adjusted to the ground level for draining out water by gravity.
• The level of eggs transfer outlet located at the centre of spawning tank should be about 10 cm. above the level of central overflow pipe at the top of the hatching tank. This will enable complete transfer of eggs from the spawning tank to use outside the tanks.
• Overflowing water from the hatching tank should not be passed on to the spawn collection tanks but should be put to use outside the tanks.
• Separate fresh-water supply lines should be installed from the overheads water tank to each tank i.e. spawning tank, hatching tanks and spawn collection tanks in order to ensure independent working of each.
• Water spraying arrangements should be provided for aeration and oxygenation in the three tanks.
• Eggs transfer pipe should discharge the water along with eggs into the hatching tank in between the two walls of the hatching tank to avoid damage of eggs.
• The walls of the spawning tanks should be provided with water inlet pipes installed in a diagonal position to create a circular water flow during the spawning period.
• Where water flow is insufficient for circulation, multiple-chambered hatching pools with paddle wheels for circulation may be constructed.
Harvesting of fry
Harvesting in nursery ponds
In nursery ponds the fry usually grow to a size of 25–35 mm in about a fortnight with more than 70–80% survival, when they become ready for harvesting. Harvesting is done by seining the pond water using a close meshed (1.45 mm) drag net. Several netting operations should be done to ensure near total harvesting of the stock. No harvesting should be done on a bright sunny day or in cloudy weather as there might be heavy mortality of tender fry due to high temperature related increased metabolism and the depletion in available dissolved oxygen. The most suitable time for harvesting is the early hours of the morning. Feeding should be stopped a day before harvesting to minimize the conditioning time required for transporting fry over long distances.
Harvesting in rearing ponds
Harvesting of fingerlings should be done after three months of rearing when they attain the desired size of 100–150 mm. However, in some cases fingerlings are to be kept for a prolonged period for marketing during the period of scarcity of seed to fetch better price. Harvesting should be done by seining the pond using a drag net of about 8.0 mm mesh. However, complete harvesting of all the species, especially the bottom feeders is usually difficult and hence several netting should be done to ensure near total harvesting. A modified form of net, which is described below, is very effective in catching all the species of carps even in rearing ponds. Feeding should be stopped a day prior to harvesting.
Transporting of fry/fingerlings
For transporting live fish and fish seed over exceedingly long distances and from one country to another, closed system of transport is most suitable. In this system of transport live fish/seed materials are packed in closed containers with oxygen under pressure with airtight seals. Polythelene or vinyl chloride or other plastic bags of various capacities ranging from 15–35 litres are in use. Number of seed materials to be packed per bag vary according to their size and expected duration of transport.
Packing density of fry/fingerlings of Indian major carps for 12 hour journey
Seed size (cm) No. of seed (Range) No. of seed (Average)
1 1000 – 10000 5500
2 500 – 5000 2200
3 200 – 1000 600
4 200 – 500 330
5 75 – 300 225
6 50 – 200 80
7 25 – 100 70
8 25 – 50 40
