Reproduction technique of tilapia

Abstract: when tilapia is artificially propagated, the overwintering parent fish can be moved to the outdoor breeding pond when the water temperature rises to about 20 ℃ in spring. The area of the breeding pond should be 1-2 mu and the water depth is 15 meters. Because tilapia has the habit of nesting and breeding, the bottom of the pool used for breeding should be loam or sandy loam. Let's take a look at the breeding technology of tilapia.

When tilapia is artificially propagated, the overwintering parent fish can be moved to the outdoor breeding pond when the water temperature rises to about 20 ℃ in spring. The area of the breeding pond should be 1-2 mu and the water depth is 1.5m. Because tilapia has the habit of nesting and breeding, the bottom of the pool used for breeding should be loam or sandy loam. Let's take a look at the breeding technology of tilapia.

Reproductive characteristics of tilapia

Tilapia has the reproductive behavior of building spawning nests when the water temperature is more than 20 ℃ in spring. The optimum temperature range for female spawning is 2432 ℃, and the critical temperature is 2038 ℃. In the middle and lower reaches of the Yangtze River in China, the spawning time generally occurs from May to September; in the north, the time interval is shortened; in the south, the spawning time may be lengthened, and the spawning time in southern Guangdong and Hainan can be propagated throughout the year. Tilapia is a typical fish that lays eggs many times a year. In the southern region, it can reproduce once every 25-30 days in summer and autumn, and 4-6 times a year. In the middle and lower reaches of the Yangtze River and East China, it can reproduce once every 30-35 days in summer and autumn, and 3-5 times a year. North China can reproduce 2-3 times a year.

Parent fish selection of tilapia

The parent fish used for breeding should choose the ones with strong physique, disease-free and injury-free, the size of the parent fish should be 150,450g, 300,400 parent fish should be released per mu, and the ratio of female to male parent fish is 2:1 or 3:1. Tilapia has the characteristics of early sexual maturity, short spawning cycle and hatching in the mouth. The requirements for reproduction conditions are not strict, generally small areas of still water ponds can reproduce. In the Yangtze River basin, Mozambican tilapia and longevity fish can be sexually matured 3-4 months after production, and the overwintering fish can reproduce and spawn within 1-2 months.

After overwintering, the physique of parent fish is relatively thin, so it is necessary to strengthen cultivation before spawning and promote the gonadal development and breeding ponds of parent fish to apply 300-500 kg of basal fertilizer per mu before being used for reproduction. After parent fish is released, 50 kg of organic fertilizer should be applied every 1-2 days, and commercial feed such as rice bran and bean dregs should be fed, which is about 3% of the body weight of parent fish. Generally, when the water temperature reaches 22-23 ℃, tilapia can lay eggs and fertilized eggs are yellowish brown, and the fertilized eggs hatch in the female's mouth. When the water temperature is 25 ℃, the newly hatched fry hatch in 5-7 days, and still live in the female's mouth. When the yolk sac of the fry disappears and has a certain ability to swim and feed, the fry leaves the mother, and a small group of fry can be seen on the bank of the pond.

Reproduction techniques of Tilapia

1. Pond selection: convenient transportation and quiet environment are required. The pond has abundant water supply, convenient drainage and irrigation, with an area of 1 mu and a rectangular shape in the east-west direction, and the mud pond ridge should have a certain slope to facilitate parent fish to dig nests and spawn in shallow water. The cement ridge can build a step with a width of 30 cm around the pool ridge at 20cm to 30cm under the normal water level, which is convenient for net operation and seedling fishing. The bottom of the pond is flat, sandy or loam, and the silt thickness is less than 10 cm. When the parent fish was first put into the pond, the water depth was maintained at more than 1.5 meters, and when it began to spawn, the water level was lowered appropriately to keep it at about 1 meter. The water quality is non-toxic and harmless. When the water temperature is 23-30 ℃, the parents will always keep producing seedlings. Filter screens are installed at the inlet and outlet to strictly prevent tilapia from running through ponds, escape and the entry of wild miscellaneous fish and harmful insects, which is especially important for the production of Oney hybrid fish fry. The parent fish should be thoroughly cleared, disinfected and fertilized before stocking.

2. Daily management: after the parent fish go into the pond, arrange special personnel to manage, establish pond management log, improve the post responsibility system, and strictly hand over the shift system. Adequate bait should be provided for parent fish throughout the breeding season. For every batch of fry produced by parent fish, a large amount of nutrition is needed to quickly restore physical strength and promote gonadal development and maturity. For this reason, the composition and quantity of bait in the breeding pond must be quite rich and diverse. in addition to proper fertilization, it is also necessary to constantly provide compound bait Song to supplement the deficiency of natural bait. Strengthen water quality regulation, maintain fresh water quality, abundant dissolved oxygen, timely injection of new water, and maintain a certain water level (1.2 meters). Persist in patrolling the pond day and night, and turn on the aerator or add new water when you find the parent fish floating head. Pay attention to the change of water temperature, especially the pool water in early spring or in the middle and later period of breeding, which varies greatly due to the influence of the weather. The suitable temperature range for spawning of tilapia is 2432 ℃. When the weather fluctuates greatly, the temperature of the pool water can be maintained relatively stable by adjusting the depth of the pool water.

3. Seedling emergence operation: about 20 days after the parent fish entered the breeding pond, the seedlings were produced one after another. At this time, it is necessary to strengthen pond patrol and pay attention to pro-fish activities and seedling emergence. Once flocks of fry are found, start fishing for fry. When fry gather around the pond in the early morning or evening, use triangulation net to fish along the edge of the pond. Take advantage of the small fish fry swimming ability is still relatively weak to step up the fish fry, as far as possible. For the overwintering parent fish just put into the breeding pond, because they are raised under the condition of high density in the overwintering pond, the development degree of most ovaries is basically similar, the first spawning is relatively synchronous, and the time of spawning and emergence is relatively concentrated. The specifications of the first batch of fish fry are neat and easy to be fished out. In the following time, due to the individual differences of parent fish, the level of gonadal development is inconsistent, the time of spawning is also uneven, resulting in different time of emergence. At this time, it is difficult to catch all the fish fry with the seedling method. When the fry that has not been fished up to 2cm long, there will be the phenomenon of large fry eating small fry, so that the amount of fry will be reduced. For this reason, it is necessary to catch fish fry with net cuttings on a regular basis, usually once a week.

4. Temporary culture of fish fry: fish fry are temporarily raised in cages, be careful not to be too dense, otherwise they will be lack of oxygen, and they should not be kept for too long, preferably no more than a week, otherwise they are easy to cause malnutrition and poor physique, which is not conducive to long-distance transportation and future breeding. The temporary recuperation period should be fed twice a day with egg yolk or soybean milk to prevent the net from breaking and turning, and the cage should be changed frequently. When the fish fry in the cage reaches a certain number, it is screened and then transferred to the nursery pond for cultivation or sale.

5. Fish fry count: in large-scale fry production, it is necessary to count whether it is stocked or sold. When marking and counting each batch of fish fry, prepare a small cup of about 20ml (the size of a small wine cup), a small spoon made of sieve silk, and several washbasins. First, slowly concentrate the fish fry temporarily raised in the cage, remove the sundries inside, and then put the fry into a small cup with a small spoon to sample, and remember the number of cups. Put one cup of fish fry into a basin to count, and then multiply the number of cups to know the number of the whole batch of fish fry. Note that the proofing action should be fast when the fish fry are gathered together, and keep splashing water gently during the proofing process.