Brood Fish Transport

In India two successful models of closed system live fish carrier tanks have been designed to carry brood fishes. One is due to Mammen (1962b), which is known as “splash less tank”. The latest model of the “splash less tank” is of petrol tanker design of 150l capacity with an auto clave type lid. It has a built in aeration system for supplying compressed air, which works on a belt driven by the engine of the transporting vehicle. An oxygen cylinder is carried only as a stand by emergency. The inside of the tank is lined by U-foam which prevents the physical injury to live fish during transport. A total weight of 250kg brood fish can be transported at a time in “splash less tank” Adult Catla weighing about 60kg has been transported in this tank successfully. Generally one kg fish is transported with 4.5l of water.

The other live fish carrier is designed in India by Patro (1968). Patro’s carrier is of a laboratory gas supply design type and comprising an outer chamber of 120cm dia open from top and slightly smaller inner one closed from top, the later during transport, fits inside the former. The inner chamber is provided with an air vent and an oxygen valve. The outer chamber serves as a storage tank and initially filled with water along with fishes to be transported. The U-foam prevents the fishes from injury during transport. The double barrel sized carrier described by Patro, can transport 100kg of brood fish at a time. The oxygen is supplied in the tank with an interval of 5hrs to keep the fish healthy.

Some chemicals are also used to transportation of live brood fish. The sedatives are used in transportation can decrease the rate of oxygen consumption and reduce the rate of excretion of carbon dioxide, ammonia, and other toxic wastes. It can control the excitability of the fish, thus reducing the chances of injury.

Natural Resources of Seeds:

In early days generally seeds of Indian Major Carps are collected from natural resources for culture in fish farms. The techniques of collection of seeds from natural resources are described bellow.

Site Selection for Collecting Fish Seeds:

Before selecting a suitable site for collection of spawn in a given stretch of river, a pre monsoon survey is generally conducted. The river meandering with oxbow lakes, flooded areas of river banks, shallow areas flooded with rain water are suitable for collection of fish seeds. The bends and curves of various shapes in the river course often show a precipitous, fast eroding bank on one side, called here, ‘erosion zone’ and a flat, gently slopping bank exactly opposite, called ‘shadow zone’. Both these banks are unsuitable for collection of spawns. Better collection sites lie on the side of the slopping bank, but at spot where the current just diverges casting off spawns to the sides, as if by centrifugal force. At such sites, a large number of spawn collection nets are usually be operated.

Gears Used for Collection of Spawns:

The spawns are collected by special type of nets, called shooting nets. This is a funnel shaped, net of finely woven netting and is operated in shallow margins of flooded rivers with mouth of the net facing the current. At the end of the net a bag like structure is attached, called ‘gamcha’ to store the spawn inside of it. After a certain periods of time, the cod the spawns are collected at this cod end. The net is fixed by four bamboo poles, against the current of rivers. Various types and modification of these nets are used in different parts of India. In North-east Bengal, the spawn collection nets are called benchi jal. In South-western part, the nets are called Midnapur type nets.

Methods of Collection:

The shooting nets are fixed in such a way that its axis is in line with current directions. To start with bamboo pole is planted firmly in the selected spot, the loops of one end of the nets mouth slipped over it, the other end is stretched firmly across the path of the current and fixed in place with the help of another bamboo pole. The net is then allowed to drift in the current, mouth facing to the current of water. The net is then stretched firmly along the axis, by pulling the cod end ring which is then fixed in place with the help of more bamboo poles. The anterior end of ‘gamcha’ is then tied round the ring, while the posterior end is fixed in position with the help of two more bamboo poles. In order to prolong the life of the net and ‘gamcha’, they should be invariably pulled out of the water after 12hrs operation and dried for at least 24hrs.

After storing suitable quantity of fish seeds, the tail pieces of nets are removed and the spawns or seeds of fishes are scooped out. The collection of seeds from tail pieces are carried on after an interval of 15min, 30min, 1hrs, or 2 hrs depending on the intensity of the collections. Before scooping, the debris accumulated inside the ‘gamcha’ are removed carefully with expertise hands.

Methods of Measuring the Quantity of Spawns:

The spawn collected is to be measured in 200ml, 100ml, 50ml, 30ml, 20ml, 10ml or 5ml measuring cups, depending upon their bulk. For temporary storage the spawns are stored in hapas, made up with muslin cloth, fixed in the shallow water of river margins or creeks.

Brood Fish Maintenance

Culture of brood fish or care of brood fish which is called brood fish management is the essential factor or key factor for successful artificial induced breeding. The benefits of brood stock management are the availability of brooders in proper condition during the breeding season. For this the healthy stock of brood fish is specially taken care in well managed ponds for proper sexual development.

Selection of Brood fish Pond:

The size of brood fish ponds may vary from 0.5-1.0ha and with depth of 1.5m-2.0m preferably rectangular shaped ponds with uniform slope. The bottom of the pond should be compact and flat with clay-loam soil with bottom silt not exceeding 10-15cm. The pond should be with controlled pipe system for complete drainage system with proper inlet and outlet facilities. Flashing system of pond is required to provide riverine condition. The pond should be well protected with flood and draught and its should be in such condition to get sufficient wind and exposure of bright day lights for at least 6-8 hrs a day for at least 2-3 months (January-February onwards) (Nataranjan, 1984). The temperature should be moderate with 27°C - 32°C, to optimise the gonad development.

Selection of Brood Fish:

Healthy disease free breeders of Catla catla, Labeo rohita, Cirrhinus mrigala with some exotic carps of 2-4yrs of age with 1-5kg of weight are normally selected.

Sources of Brood Fish:

The brood fish are selected from different river systems, to avoid inbred species. Brooders can also be selected from selective breeding process. The better brood fish can also be selected from different farms or different lakes or reservoirs. To prevent inbreeding in a hatchery, it is necessary that fresh fish germplasm from natural sources are introduced regularly with timed periodicities. If it is not done, inbreeding depression may set in, which is apprehended to have occurred in some existing aquaculture system in India.

Stocking of Brood fish

Stocking of fish is done @ 1000-3000kg/ha with species composition of 4:3:3. That is surface feeders catla – 30 to 20 and silver carp 10 to 20, depending upon the concentration of phytoplankton. The column feeder i.e. rohu 20 and grass carp 10 with bottom feeder i.e. mrigal 20 & common carp 10. The species ratio appears to be quite proportionate in Indian tropical environment since the different niches of water bodies are fully exploited. Brood fish can be stocked in following ways also,

· Sex-wise segregation of all six species individually or sex wise stocking in individual brood fish ponds; this system will require 12 brood fish ponds.
· Segregation in following way i.e. common carps in 2 ponds, catla in 2 ponds, and others in 2 ponds needs 6 ponds.
· Segregation of catla in 2 ponds and others in 2 ponds can be done also, if the numbers of ponds are not sufficient.
The reason why catla is especially sought to be separated from rest of the species, if sufficient numbers of brood fish ponds are available, is that relatively the species shows considerable frigidity to hormonal injection due to ill understood reasons and it is believed that catla spawners need special diet such that deposition of mesenteries fat in the maturation phase dose not hinder gonad development of the species.

Fertilisation of Pond:

Initial manuring of brood fish pond is done by 3 weeks prior to stocking with cattle dung @ 20,000kg/ha or compost manure prepared from land/aquatic weeds and farm animal droppings at the ratio of 1:1 with 5% quick lime @10,000kg/ha. A prophylactic quicklime treatment @ 200kg/ha given in the pond 7 days before of manuring. Monthly dose with raw cow dung @ 2000kg/ha are given also.

Constant manuring and using heavy supplementary feed may cause repressive factor (Swingle, 1956) and this might inhibit the maturation to the point of ovulation and spawning of fishes in the captivity. Frequent changes of water (monthly, fortnightly or weekly) can reduce the chances of accumulation of metabolic wastes. Fresh ground water/canal water/rain water at the volume of 1/4th or 1/8th of the total volume of water in each operation. Sudden lowering of temperature are beneficial for maintain good health of breeders and development of this gonads.

Others Management:

Regular netting should be done to increase the D.O level in the pond water. Regular netting is helpful to exercising the fish in the pond water also. It removes the harmful gases from the pond bottom also.

Supplementary Feeding:

Supplementary food is given to the breeders with well balanced food at a fixed schedule until the water blooms appeared, when the feeding is stopped. The feeding is resumed after disappearance of the bloom.

Composition of Feeds:

· The semi-composite mixture – prepared from half-cooked rice and pulses (1:1, 50%)
· Oil cakes – 20%
· Cattle dung – 20%
· Fish Meal or Silk worm pupae
· Cooked slaughter house refuses – 10%

The food should be given in sunny days, and stopped in cloudy days. Supplementary foods with vegetative matter such as Hydrilla, Vallisneria, Najas, Utricularia, and soft young leaves of other plants are given some times as food for better results. The grass carps are always fed with vegetative matter. Thick planktons – Spirulina, Oscillatoria and Chlorella are cultured and given to the pond for silver carp. The feeding rates should be lowered with the maturity of gonads. Feeding should be stopped before a week of breeding.

Inducement:

To accelerate the gonado-somatic development, HCG (activity 30 IU/mg powder; dilution of the prepared solution 10mg/ml distilled water is administered to catla and grass carp spawners at 5mg/kg body weight at one month intervals during last week of December, January & February. Rohu & Mrigal are dealt with two doses of HCG at 4mg/kg of body weight in the last week of December and first week of February. Silver carps do not any maturation dose. The HCG administered fishes are found to attain maturity relatively faster than the non injected fishes. A fairly good percentage of brood stock achieved full maturity between last week of February & middle of March, when their first breeding can start.

Some Important Steps:

1. If the fishes appear to surface, due to depletion of oxygen, application of manure and supplementary feed should be stopped.
2. To add fresh water to the pond
3. To agitate the pond water
4. Small pieces of banana plants to scattered in the pond
5. To carry out repeated netting in the pond
6. To apply common salt @ 30-40kg/ha
7. If the snails are coming out of the pond during day time signifies that their would be severe oxygen depletion at night.

Induced Breeding

Induced breeding is a technique whereby ripe fish breeders are stimulated by pituitary hormone or any other synthetic hormone introduction to breed in captive condition. The stimulation promotes timely release of sperms and eggs.

History of Induced breeding: The technique of induced breeding was first evolved in Argentina after producing pituitary extract by Houssay 1930 where viviparous fish was injected with the hormone to make premature birth. In the year of 1934, Brazilians were succeeded in induced breeding by pituitary extract. This technique was also followed in America (Merlin & Hubs) and in Russia (Gerebilisky). In India first attempt of induced breeding was made by Khan in 1937 on Cirrhinus mrigala. Later in 1955 Dr. Hiralal Choudhuri applied this technique in minor carps (Esomus danricus, Pseudeotropius atherinoides). Ramaswamy and Sunderaraj first induced to breed Clarias batrachus & Heteropneustes fossilis. The first successful induced breeding on major carps was done by Dr. Hiralal Choudhuri 1957– Cirrhinus mrigala, C. reba, & Labeo rohita. Parameswaran & Alikuni successfully bred the exotic Chinese carps – Hypophthalmichthys molitrix & Ctenopharyngodon idella in 1963.

Why Fish does not breed in Captivity??

Many cultural farm fishes like IMC do not breed in captivity. The reason may be environmental and consequently hormonal. Certain environmental parameters like photoperiods, rain, temperature, current of water influence the hormonal activity from pituitary and gonads. Disturbances arise in environment may cause the insufficient release of hormones in captive conditions and thus, the fish does not breed in captivity.

Other factors like poor foods or insufficient natural foods, exposure to biocides and other pollutants badly affect the maturation of ovary.

Why induced breeding is necessary??

The technique of induced breeding gives very promising result in fishery point of view due to –
· It gives pure spawn of certain species of fishes under cultivation. Spawn collected from natural water is not pure as because some undesirable wild species may come with them in culture pond. Sorting of pure seed is quite impossible in those stages. In later stages it is possible, but time consuming.
· It assures timely available of pure seed, where as in nature the availability of seed is quite uncertain.
· It can fulfill any quantity of demand in any time.
· It also cuts short the holding potential spawners over long periods in uncertain hope of their breeding in time. Many carps take their full maturity in confined water but do not breed.
· The technique is very simple and does not need too much technical assistance or knowledge. It can be easily learnt by a layman without much training.
· The cost of expenditure is very low than the natural collections of spawns.

Technique of Induced breeding:

Preparation of Pituitary Extract – For preparation of gland extract the glands are removed carefully from freshly killed fish called donor fish. For best result the donor fish should be fully ripe and mature. Common carp is the best donor fish, because it breeds through out the year and the individuals are available in all parts of the world. The pituitary glands of such species are relatively large. The gland should be collected prior to spawning. However the gland doesn’t show species specificity and any carp species can be used as donor. However the glands of relative or closely related species show best result.

Removal of Glands –

The removal of glands can be done by following two processes:

Removal through foramen magnum – the foramen magnum was first exposed by removing vertebral parts adhering to skull. Fat is removed first by means of forceps and then cotton piece. A pair of forceps then inserted into foramen magnum dorsally to the brain and anterior part of the brain now detached and remaining is carefully lifted out through the foramen magnum. The gland is then located and removed.
Removal of gland by dissecting head – This technique is not used commercially as because the heads are damaged by this process. The first method of removal is less time consuming and economical as the heads are used for human consumptions later. At first the head is dissected using sharp butcher’s knife, a portion of scalp is chopped off in a clean cut with one stroke. Fat surrounding the brain is removed with the help of cotton. Olfactory and optic nerves are now severed, and then brain is lifted up and removed. Locate the gland. The gland may come up along with the brain or may remain behind on the floor of brain cavity often covered with a membrane. In any case the gland is carefully removed after separating it from membrane or the brain proper. The gland must not be damaged or torn.

Preservation of Glands:

The gland after removal needs to be preserved for certain periods or for future use. The glands are taken in absolute alcohol and can be stored in room temperature. In certain countries like Russia the glands are preserved in acetone at 10°C. The glad may be preserved in refrigerator immediately for certain periods. But alcohol preservation of glands is very common and easy methods. It is widely used in India. Glycerin preservation is another technique but less popular in our country.

Preparation of Pituitary Extract:

The preserved glands of known quantity are taken out and macerated in a homogenizer after evaporation of alcohol with little amount of distilled water. Then the extract is freed of suspended particles by means of centrifugation. It is the diluted with required amount of distilled water or 0.3% saline water or a suitable physiological solution. The extract is now ready for use.

Preservation of Extract:

The extract can also be preserved for future use. In this process in place of saline water glycerine is used and extract can be preserved in room temperature or in refrigerator. Other methods of preservation are done by propane and trichloro-acetic acid in place of glycerine.

Selection of Brooders:

Proper selection of are the key of success in case of induced breeding. The breeders should be healthy, fully ripe and of medium sized. They should preferably come into the age group ranging from 2 – 4yrs and have the weight of 1 – 5kgs. Large sized breeders are avoided for difficulty in handling. For ripe male and female carps, it can be easily identified. The male shows roughness on pectoral fins when belly pressed milt freely oozes out. The ripe female shows relatively smooth pectoral fins and operculum. The eggs are released when the belly is pressed smoothly in female. The belly of ripe female is generally soft and round or budged. The vent is swollen, protruding and pinkish in colour. It is wiser to practice to keep ready adequate stock of potential brooders. For this a few months before breeding season potential breeders are kept away under care, and fed on supplementary feed (rice bran and oil cake mixture).

Injection to the breeders:

The pituitary extract is administered into the body of breeders by means of hypodermic syringe either intra muscular or intra peritoneal. To ensure a higher percentage of fertilisation during induced spawning it is necessary that there is synchronisation between ovulation and milt shading. This difficult to achieve with a set of breeders having one male and one female. Therefore the common practice is to use a set consisting of one female and two males.

Determination of correct dosage of pituitary extract to be given to the breeders is very important though a difficult matter. Dosage depends upon the size and state of maturity of the recipient (breeders) as well as upon the state of maturity of the donor for the glands. It has been found that the potency of the gland is influenced by the size, the age, the sex, the state of sexual maturity of the donor fish as also the size of the gland itself. Great difficulty is encountered because it is not easy matter to ascertain the state of maturity of fish from external examination. Usually the female is given a preliminary dose of 2-3mg/kg of body wt. The preliminary dose is not given to the male. After an interval of time about 6hrs a second dose of 5 – 8mg are given per kg of body wt of female. The male was given then the first dose of injection with female @ 2-3mg/kg of body wt. The dose may be depending upon the maturity of fish, age, sex and also the environmental conditions.

For intra muscular injection the fish is laid on its side while held in hand net and the needle is inserted either in the caudal peduncle or in the shoulder. For intra peritoneal the injections are given in the bases of paired pectoral fins. But it is avoided because less expert hand can puncture heard of the fish.

Spawning:

After injection to the brooders a set of brooders are released into breeding hapa. In hapa breeding the hapa is the fine netting, rectangular in shape and is held by four bamboo poles one at each corner. Closed meshed mosquito netting is preferred for that purpose, as its meshes will allow a good circulation of water and will also not let the laid eggs and milt escape through the meshes. The hapa measures the range of 3m × 1.5m × 1m for breeders weighing to 3 to 5kgs. The height of the hapa should remain about 20cm above to the level of water. The roof can be open or closed. The roof can be opened or closed.

The spawning takes place with in 3-6hrs following the second dose. It turns out the midnight if the second injection was given in the evening. Successful induced breeding results in the spawn of fertilised eggs. The fertilised eggs are transparent, pearl like where as unfertilised eggs are opaque or whitish.

Factors influencing the breeding:

Climate - 24°C to 31°C with cloudy days and rainy periods. Light drizzling following heavy rains is ideal. In absence of rain artificial showers are used.
Water – Flowing water is preferred.
Turbidity – 100ppm 1000ppm.
Light – It is known to bring that light may help in early maturation and spawning of fish.

Linpe Method of Induced Breeding

Working together, Canadian and Chinese researchers have now developed a fish breeding method that increases the efficiency of aquaculture production. Injecting a GnRHa followed by (or in combination with) a dopamine antagonist has been called the Linpe method, after Lin, Hao-Ren; Peter, R.E. 1988, the researchers who started it. Most of the work resulting in the Linpe method was done on cyprinids, and there is convincing evidence for these fish that the method is effective where injection of GnRH alone is not. Linpe method — induces ovulation in female fish by injecting them with a combination of a synthetic gonadotropin-releasing hormone analogue (LHRN-A) and the drug domperidone. The hormone stimulates the sex organs of the fish, while the drug inhibits the action of dopamine, a substance produced by the fish that inhibits ovulation.

With traditional fish spawning methods, carp, for example, are raised and killed to produce a pituitary extract used to induce spawning. Many fish are sacrificed in the process and the extract has a poor shelf life. The technique also requires that fish are injected at two separate intervals to induce ovulation.

The new method reduces the cost of production, increases the supply of seed fish, and is more convenient. Rates of spawning, fertilization, hatching, and survival were significantly higher in research trials than could be achieved with pituitary injections. The hormone and drug can be introduced together, which means that brood fish stocks are handled only once, reducing the risk of disease or damage to the fish. This method does not alter the reproductive cycle of the fish, and the fertility and viability of offspring are normal. The solution does not require refrigeration and has a long shelf life. It has been tested on a wide range of fresh, salt, and brackish water species, including carp, bream, salmon, catfish, loach, and others.

It is tempting to generalize about the superiority of the Linpe method for all cultured fish, but because comparative experiments under field conditions - GnRHa-domperidone versus GnRHa alone - have only been done for carps; it is still too early to do this. Some researchers have tried to put fish in categories that reflect the strength of dopamine inhibition, ranging from cyprinids (strong dopamine effect) to salmonids (weak dopamine effect). The danger of making this kind of list relates to what we have already said about differences in the effect of GnRH itself: factors such as the general readiness of the fish can outweigh any advantage or disadvantage of a particular treatment.

The commonly voiced view that marine fish do not require domperidone along with GnRHa requires more proof; in milkfish and mullet, for example, two of the most important warm-water marine species, there are no published reports of its having even been tried. Until use of the Linpe method is more widespread, we will avoid such lists. In species that become fully sexually mature in captivity and respond to GnRHa readily - many salmonids fall into this category - a dopamine antagonist is not needed. In other species - the best evidence is still from cyprinids - even though they will spawn with GnRHa alone, delay to ovulation is shorter and more predictable when domperidone is added. Administering the two drugs is easy, with a single injection of a mixture being as effective as two separate injections. This has led to the manufacture of a commercial GnRHa-domperidone spawning~kit" that combines the two in a single solution (Ovaprim-C@). Enterprising fish farmers can of course always opt, as in Thailand, to buy GnRHa and domperidone as over-thecounter pharmaceuticals, and reconstitute them for injection into fish.

According to Dr. Lin Hao-Ran of China's Zhongshan University, the Linpe method has become "...more and more popular in Chinese fish farms and has replaced the traditional fish spawning methods in recent years". Dr. Lin has established a commercial operation to sell the active compound in China through the Ningbo Hormonal Products Factory in Ningbo City.

Commercialization was identified as a specific objective in Phase II of the research project. In addition, Syndel International Inc. has submitted an application (pending) to register Ovaprim at the regulatory agency in China, after running clinical trials in Wuxi, Beijing, and Harbin in 1994.

Linpe method (domperidone/sGnRH-A) of induced spawning of cultured freshwater fish are used in many countries, for leading to commercialization of the method; to determine the effectiveness of sGnRH-A and domperidone in induced ovulation and spawning of marine teleosts; to determine the effects of aging on reproductive function of key species in the Chinese freshwater polyculture system; to determine means of increasing growth rates of cultured fish and; to continue the training of young Chinese scientists in relevant disciplines.

Doses of GnRH and domperidone

Although there will never be a standard method for spawning all species, culturists working with a single species can standardize methods by systematically eliminating sources of variability and using the lowest effective dose. Effective doses of GnRHa and domperidone vary widely and are not comparable because of differences in species, temperature, state of maturity, and GnRHa. The trend is toward single injections and, although GnRHa doses between 1 and 100 ~g/kg have been effective, culturists should aim for the 5-20 ,~g/kg range. Domperidone is usually effective at doses of 1-5 mg/kg.

To facilitate economical use of GnRHa, without the need for tedious weighing of tiny amounts, it is best to buy preweighed small amounts of the hormone (e.g., 0.5 or 1 mg aliquots) and prepare a concentrated stock solution (e.g., 1 mg/mL) in sterile water in the original container. Appropriate amounts of a more dilute solution in 0.7% NaC1 can then be prepared at the time of injection. GnRHa is most stable as a dry powder, but the sterile stock solution can also be kept for several months if frozen.

Domperidone and pimozide are not readily soluble in water and are sensitive to oxidation. They are best used as a suspension in 0.7% NaC1 containing 0.1% metabisulphate as antioxidant, or can be dissolved (and injected) in propylene glycol. Commercially available domperidone tablets for humans (Motilium0) have been powdered, dissolved in propylene glycol, and used uccessfully in induced reproduction of fish (Fermin 1991).

Multiple Breeding

Carp seed production is no more confined to monsoon months. Now a days carps have been domesticated to breed much ahead of monsoon and months beyond the monsoon, ensuring the seed during pre and post monsoon periods. Such availability of carp seeds promises success in intensive carp culture practices. It also can compensate the loss of seed due to the natural calamities like flood and draught etc. surprisingly the brood involved in pre-monsoon are not different individuals but one and the same as professional brood.

Pre-monsoon Breeding: Success in Pre-monsoon breeding depends on a precocious gonad maturity. This can be achieved by simple brood stock management practices. Pre monsoon breeding commences as early as March. The yield is 0.5 – 0.6 lakh spawn/kg body weight of fish. Second spawning of same fish is achieved with in a time interval of 40 – 45 days. The production rate increases to 1.0 – 1.5 lakh spawn/kg body weight. Both the spawning are completed between March & May.

Monsoon Spawning: A time lapse of another 40-45 days following the second spawning brings the 3rd crop (June-July). During this period climatic conditions are more favorable than any other breeding period and they yield further increases to 1.5 – 2.0 lakh spawn/kg of body weight.

Late Monsoon Spawning: Quality of mature eggs can not be maintained in situ for indefinite period. Therefore, monsoon dependant traditional broods are not useful for late monsoon breeding. This is possible only to spawn when the same fish repeatedly with an optimum time interval between two successive spawning. The fish has already spawned two or three times in a seasons expected to come for late monsoon breeding i.e. between August & September. However, the yield of spawn declines when compared to monsoon breeding.

Principle of Multiple Spawning: Multiple spawning is the timely harvesting of mature gametes repeatedly by more than two spawning. The fishes are bred by adopting routine hypophysation technique. Major carps have been bred as many as four times between March and September. Brood recovery I to II and II to III within the stipulated period (March – August) is observed almost 100%. Further re-maturation rate declines 30 – 50% which may need some more management manipulation for the purpose.

Brood Stock Management and Multiple Breeding:

Gupta et al (1990) reported advancing maturity spawning of Asiatic Carps during April & May through brood stock management. Futher maturity could be preponed by following improved management practices for which spent brooders of proceeding breeding season are preferred as the initial stock for the programme. However the age of the fish should be 2 to 3+ years stocked at 1000kg/ha. They are fed on formulated protein rich feed fortified with vitamins and minerals at 1-2% of their body weight. As water replenishment has a considerable impact on gonadal maturity of fish, it should be done twice a month preferably with fresh canal/reservoir water from February to May. Other management practices are of routine nature. Such managed brooders show precocious gonadal maturity at least three months earlier than monsoon dependant in the locality.

Breeding Status of Multiple Spawners:

Type of brood raised for such multiple spawning is termed as professional brood. These broods certainly spawn early and show better breeding response as compared to brood maintained for monsoon dependant traditional breeding. The brood 4 – 5+­­ years of age show consistent yield of spawn. Therefore, it is essential that the overage fish should be excluded from the multiple broods, rearing programme. Further, to build up a stock of professional brood is a continuous process for successive multiple spawning programme.

Care of Multiple Breeding:

Spent brood monitoring programme is an important aspect better survival and recovery of the spent brood, most care is suggested at every stage for handling as follows.

· The brood should be transported in the canvas bags along with water
· Hormone administration should preferably be intraperitoneal which reduces the stress of injection.
· Stress should be minimized in spawning pool by providing required flow and duration of water supply in the pool for spawning.
· Spent brooders should be removed from spawning pool as soon as breeding operation is over.
· Spent brooders should be treated at regular intervals with potassium permanganate solution (5 ppm). This keeps a check on secondary infection and also quickens recovery from spawning stress.
· Feeding and other management practices should be followed meticulously for subsequent maturity.

Larval care:

The performance & Survival of spawn produced through multiple breeding are comparable to that of traditional seed. However, spawn produced through multiple breeding need special care as the yolk gets absorbed within 60 hrs of fertilization. So food is essential after 60 hrs of fertilization. The food may be micro-plankton or particulate materials suspension.

Conclusion:

It is possible to produce seed during pre-monsoon, monsoon and late monsoon in a calendar year. A cumulative yield of spawn per kg body weight of fish is enhanced to 3 – 4 folds than single breeding. Further cost of seed production is reduced. It also provides opportunity for multiple cropping in aquaculture practices.

Bundh Breeding

Alikunhi et al (1960) stated that “Bundhs are specialized ponds where the condition of reverine flow are created by constructing embankments against the large catchment area, subjected to rapid flooding during monsoon” Bundh are special type of perennial and seasonal pond or impoundments where reverine conditions are simulated during monsoon months. The bundh after heavy rain, receive large quantities of rain water, washing from their extensive catchment and provide large shallow marginal areas which become the spawning ground for carps. Bundh-breeding, this is prevalent only in the States of Madhya Pradesh and West Bengal, accounted for 5.38% of the total fish seed production in the country. It is however, reported that wet bundhs are existent in certain parts of Andhra Pradesh, Uttar Pradesh and Bihar, wherein breeding of major carps reportedly takes place; but no definite information as to their occurrence and magnitude is available with the concerned State Governments.

Bundhs are Two Types:

1) Perennial Bundh – Wet Bundh
2) Seasonal Bundh – Dry Bundh

1. Perennial Bundh – Wet Bundh: A wet type of bundh is a kind of small or large perennial pond or tank, from a few acres to over a square mile, in the midst of a low-lying and bounded on three sides by high embankments. In summer, generally a quarter parts of most of these bundhs dries up and is cultivated, with the central part, deeper than the surrounding area, always contains some water and harbors mature fish

Many large irrigation tanks having rich coverage of forests wood/fields in the catchment can also serve as good wet bundh. After heavy monsoon shower, freshwater with washing form the upland areas rushes in the bundh and the major portion of the tank or reservoir may even overflow, the excess water being drained out through the outlet known as “bundhs”. The outlet is protected by bamboo fencing known as “Chhera”. The shallow gradual slopping is know as “Moans” in W.B. are the main spawning ground. As soon as the monsoon starts, with first and second heavy shower the wet bundh gets inundated, particularly the gradual slopping area with run off water. It stimulates the fishes in the bundh and they migrate to the shallow marginal area, start breeding in suitable ground.

2. Dry Bundh: A dry bundh has been described as a shallow depression enclosed by an earthen wall (locally known as bundh) on three sides, which impounds fresh rain water from the catchment area during the monsoon season. Such impoundments, which remain more or less dry during a greater part of the year, are known as dry bundhs.

The topography of the land has a great role to play in the location and distribution of dry-bundhs. The undulated land, which provides a large catchment area and facilities for quick filling of the bundhs even with a short rain and at the same time quick and easy drainage due to gravitation, in the Midnapore and Bankura districts of West Bengal has specially favoured the construction of large number of such bundhs in the private sectors. In Madhya Pradesh, dry bundhs are mainly distributed around Nowgang in Chhatrapur district, where topography of the land and the soil type are almost similar to that in the two districts of West Bengal referred to above.

Spawning in both wet and dry bundh usually occurs after continuous heavy showers for days, which large quantity of rain water rush into the bundh. The technique adopted for dry bundh breeding from time to time in different areas may be broadly classified in two stages which are presented bellow.

First Stage: - In this stage after accumulation of sufficient rain water brooders were transferred from some other perennial ponds, generally during rainy days, in Bundh. No importance is to be given to the brooders related to maturity and sex ratio. By inlet & outlet flow of water created & this breeding is observed within 3-4 days. After total dewatering the eggs are collected. In single season three operations can be done.

Second Stage: - The technique adopted in this stage is much improved as it was done by better understanding of sex ratio, size and no. of brooders. Fully ripe male and female (1:2 in number & 1:1 in weight) are introduced with accumulated rain water in rainy days, with injecting 2-3 sets (sympathetic breeding). Successive spawning could also be achieved as five times in one times in one seasons (Dubey 1969).

Synthetic Hormones Used in Induced Breeding

Human Chorionic Gonadotropin (HCG):

Human Chorionic Gonadotropin (HCG) is a glycoprotein hormone produced by the placenta in pregnant women. During early pregnancy the hormone appears in the urine in large quantities. When it is injected to the mature fish, the hormone is known to cause the release of gametes. It is thought that the action of releasing gametes is due to the joint action of pituitary glands hormone and HCG. Generally when HCG is injected singly it does not give good result. So it is injected with pituitary gland extract.

In India the use of HCG was started late in 1980s. Both Indian and Chinese carps show good result.

HCG is cheap compare to pituitary extract and has long shelf life. The product is grinded in distilled water (2mg in 0.2ml) and centrifuged. The supernatant is used as injection. The first injection is given to female followed by second dose of injection in both male and female. In second dose the mixture of HCG and pituitary is used. The dose is weight dependent.

Other New Generation Drugs:

A number of new generation drugs are also be used in place of pituitary gland extract. These are very efficient even in lower doses also and cheaply available. Some important drugs are –

Ovaprim (Salmon Gonadotropin): “Ovaprim” is a very efficient drug in place of pituitary extract produced by salmon Gonadotropin RH and Domperidon. It is available in India after 1988 and extensively used. In India good result is shown in West Bengal, Madhya Pradesh, Andhra Pradesh, Karnataka, Kerala, Orissa, and Maharashtra. This hormone is given in very low quantity to the IMC which gives best result. The results suggest that intervention of “Ovaprim” holds considerable promise in future. It is the product of Syndal Lab. Ltd. Canada, distributed in India by Glaxo India Ltd. Mumbai.

Pimozide: It is a dopamine antagonist having ovulatory role of LH-RH- A. It is quite effective in IMC. The LH-RH (Luteinising Hormone – Releasing Hormone) and its analogue LH-RH- A are very effective on brackish water fish – Mugil and Lates. They are cheap but the hormones are short lived.

DOC A: (II-Desoxycorticosterone-acetate) is another very effective drug which has been tried in cat fishes – Clarias & Heteropneustes. They not only help in ovulation but also in maturation of eggs. However, the commercial importance is low due to the high cost.

Anti oestrogen tamoxifen (anti androgen): This hormone gives promising result in Coho-salmon especially when it is administered with pituitary extract. This anti androgen can bring early ovulation. Still the hormone is in experimental result.