Artificial breeding techniques for breeding rainbow trout

Rainbow trout, native to California, USA, is a precious cold-water farmed fish with delicate meat, delicious meat, rich nutrition, rapid growth, easy fishing and simple artificial reproduction. It was introduced into China in 1959 and is now farmed in most parts of the country. There are many streams, cold springs and reservoir bottom drainage in rural areas of our country, so rainbow trout can be raised according to local conditions.

Artificial propagation

Rainbow trout is sexually mature at 2 years old, the breeding season is winter and early spring, and the water temperature is between 6 ℃ and 13 ℃. The spawning period is greatly affected by water temperature and light. Rainbow trout fertilized eggs hatch for a long time, and it takes about 30 days to hatch small fish at 10 ℃. Its artificial propagation technology includes four steps: parent fish cultivation, egg collection and fertilization, hatching and seedling cultivation.

1. Parent fish cultivation

In order to obtain physically strong and fast-growing offspring, in addition to avoiding inbreeding, the first sexually mature parent fish are generally not used. the hatching grains of these fish are small and the vitality of the offspring is weak. Therefore, parent fish for breeding should be selected and cultivated from 2-year-old fish, the body weight should be more than 1 kg, and the ratio of male to female should be 3-5 ∶ 1; the stocking density should be 1-2 per square meter, mixed culture of male and female, and should be raised in separate ponds about 1 month before breeding to facilitate operation. The annual water temperature of parent fish should not be higher than 17 ℃. If it exceeds 17 ℃, it cannot mature. At the same time, the quality of eggs is also closely related to the nutritional composition of feed. In feeding, vitamins should be increased appropriately, and fat feed should not be fed more. The crude protein, crude fat and carbohydrates in parent fish feed should be higher than 40%, 6% and 12%, respectively. The period from August to September is the recovery point of gonadal development of parent fish. Feeding should be strengthened and nutrition supply should be strengthened. The amount of feeding should be about 3% of body weight. Two months before spawning, bait should be reduced accordingly, and bait should be stopped 2-3 days before spawning. Where there are conditions, in the prenatal and postpartum period of parent fish, all can be fed with animal feed such as fresh miscellaneous fish.

two。 Artificial egg collection and insemination

After the female fish matured, the foreabdomen was large and soft, the reproductive foramen was red, swollen and protruding, there was a sense of egg separation in the abdomen by hand touch, and there was an outflow of eggs from the reproductive pore after light pressure. Mature male fish with milky semen flowing out of the abdomen after extrusion. At this time should be timely egg collection, insemination, otherwise, easy to over-mature phenomenon, the loss of fertilization ability. The maturity of males should be observed every two days during the breeding season.

Egg collection and insemination should be carried out indoors to avoid strong light. During artificial insemination, the eggs were gently squeezed into a clean washbasin and washed with isotonic solution (sodium chloride 55.05g, potassium chloride 1.97g, calcium chloride 3.14g, distilled water 7.5ml 8.0L solution, and PH value adjusted to 7 with sodium bicarbonate). Filter out the isotonic fluid and quickly squeeze into the semen, stir with goose feathers to make the eggs uniform, then add a small amount of water, then stand for 1 minute, wash the eggs with water for 2-3 times, add water and stand for 2-3 hours. Move into the incubator when the egg absorbs water and expands flexibly.

3. Incubation

When hatching, the running water is hatched in the incubator, and the water used for hatching must be filtered, requiring fresh water quality and sufficient dissolved oxygen. Use 2-4 liters of water per ten thousand eggs per minute. Incubation temperature 7 ℃-13 ℃, strictly avoid light in the process of hatching, timely removal of dead eggs (10% salt water to separate dead hatching, dead hatching due to small proportion and floating). In order to prevent water mold infection, 3-5 grams of malachite green can be put into each cubic meter of water.

Seedling cultivation

Seedling cultivation refers to the cultivation of hatched larvae to 2.5 cm-3 cm long. The newly hatched fry are very delicate, nourished by the umbilical sac, afraid of bright light, and control the amount of water, 30-50 liters per minute for every 100000 fry. When the water temperature was 10 ℃, after 23 days, 2 / 3 of the umbilical sac was absorbed, and the fry were transferred to the feeding tank or cement pond. The stocking density is 10,000 per square meter, and 20 litres of water is needed per 10,000 per minute. Live bait (giant water flea, water earthworm), cooked egg yolk and minced fish should be used when the larvae float at 60% of 70%. The bait can be sifted with a 0.4mm mesh and fed 6-8 times a day, with a daily feeding of 10% 15% of the fish's body weight; the water temperature is 10 ℃-15 cm, and after 20 days of cultivation, the body length can reach 2.5cm-3cm, which can be transferred to the outdoor fish pond for cultivation.

Before stocking the fish pond, disinfect and clear the pond with quicklime and install a 2mm-3mm mesh gate. Before entering the pond, the fish should be screened and raised in separate ponds, so as to prevent the big fish from competing for food and affecting the growth of the small fish. The stocking density depends on the dissolved oxygen in the water, the amount of water injected and the specification of fish species. Weight 3 grams-5 grams per square meter 200, water flow 10 liters per second. The minced fish were mainly fed with minced fish within 20 days before breeding, with daily feeding amount of 6% Mel 10%, bait 4 times per day; after 20 days, compound feed was used, daily feeding amount was 2% Mel 4%, and bait was given 4 times a day. In order to meet the nutritional needs of the growth and development of fish fry, in addition to artificial compound feed, but also some water fleas, tadpoles and other live bait. In the process of feeding, we should pay attention to control the amount of water injection, often wash the gate, prevent the gate from clogging, lack of oxygen, and often remove the dirt and residual bait at the bottom of the pond to maintain a good environment, which is conducive to the growth of fish species.