Rainbow trout originated in California, the United States, is a precious cold-water cultured Fish, its delicate meat, delicious meat, nutritious, rapid growth, easy fishing, artificial breeding simple. It was introduced into China in 1959. At present, most areas of the country have aquaculture. There are many streams, cold springs, and reservoir bottom drainage in rural areas in China, and rainbow trout can be raised according to local conditions.
Artificial Propagation
Rainbow trout are mature in the second age, and the breeding season is winter and early spring. The water temperature is between 6°C and 13°C. The spawning period is greatly affected by water temperature and light. The incubation time of rainbow trout fertilized eggs is longer, and it takes about 30 days at 10°C to hatch small fish. The artificial propagation techniques include four aspects of broodstock breeding, egg collection and fertilization, hatching and seedling cultivation.
1. Broodstock breeding
In order to obtain a healthy and fast-growing offspring, in addition to avoiding inbreeding, generally the first sexually mature broodstock is not used. These fishes have small instars and the vitality of offspring is also weak. Therefore, breeding broodstock should be selected from the 2nd instar fish for cultivation. The body weight should be more than 1kg, and the ratio of male to female should be 3～5:1; the stocking density should be 1 to 2 tails per square meter, and the male and female polyculture to breeding. About 1 month before, it should be kept in separate ponds for operation. The annual water temperature for feeding broodstock should not be higher than 17°C. If it exceeds 17°C, it cannot mature. At the same time, the quality of the eggs is closely related to the nutrient content of the feed. It is necessary to increase the amount of vitamins in the breeding and it is not appropriate to feed more fat feed. Crude protein in broodstock should be higher than 40%, crude fat should be less than 6%, and carbohydrate should be less than 12%. August-September is the rising point of gonad development in broodstock. Feeding should be strengthened and nutrient supply should be strengthened. The amount of feeding should be about 3% to 5% of body weight. Before the two months of spawning, feeding should be reduced accordingly. Before spawning, Stop bait for 2 days to 3 days. Wherever conditions permit, pre- and post-natal feeding of broodstock can be fed on all animal feedstuffs such as fresh scads.
2. Artificial egg insemination
After the female matures, the anterior ventral is large and soft, the genital pores are swollen and protruded, and the hands touch the abdomen with a sense of separation of the eggs. After light pressure, the abdomen has an outflow from the genital pores. Mature males have milky white semen out of their abdomen after extrusion. At this time should be timely spawning, insemination, otherwise, it is prone to over-maturity, loss of fertility. The maturation of male fish should be observed every two days during the breeding season.
Egg insemination should be performed indoors to avoid strong light. For artificial insemination, the eggs are gently squeezed into a clean washbasin, using an isotonic solution (sodium chloride 55.05 g, potassium chloride 1.97 g, calcium chloride 3.14 g, distilled water 7.5 to 8.0 liters, and bicarbonate Sodium pH is adjusted to 7) Wash eggs. Remove the isotonic fluid and quickly squeeze into the semen, stir with goose feathers, make the eggs even and then add a small amount of water, then stir a little, let stand for 1 minute, then wash eggs 2 to 3 times with water, add water to stand 2 hours to 3 hours, when the egg is full of elasticity, it is transferred into the incubator.
3. Hatching
During hatching, run-water hatching is performed in the hatchery tank. The incubation water must be filtered, requiring fresh water and adequate dissolved oxygen. Each 10,000 eggs use 2 liters to 4 liters per minute. Incubation temperature 7 °C ~ 13 °C, strictly avoid light during the incubation process, timely removal of dead eggs (with 10% saline solution to separate the dead hatch, dead hatch due to a small proportion of floating). To prevent saprophytic infection, 3 g to 5 g malachite green can be placed in each cubic meter of water.
Seed cultivation
Seed cultivation refers to incubation of larvae to 2.5 cm to 3 cm in length. The newly hatched fry is very delicate, with nourishing umbilical cysts, strong light exposure, and good water control. The water injection rate per 100,000 fry is 30 to 50 liters per minute. At a water temperature of 10°C, after 23 days of absorption of the umbilical cysts, the fry were transferred to feeding tanks or cement ponds for rearing. The stocking density is 10,000 per square meter, and 20 litres per minute per 10,000 water needs. When the larvae have 60% to 70% float, they should feed live bait (large leeches, leeches), and they can also cook egg yolks and fish quails. The bait can be fed with 0.4 mm mesh fine sieving and fed 6 times a day. 8 times, daily feeding is 10% to 15% of fish body weight; water temperature is 10°C～15°C, after 20 days of cultivation, the body length can reach 2.5 cm to 3 cm, and it can be transferred into the outdoor species pool for cultivation.
Fish ponds should be disinfected with clear lime before they are stocked, clear ponds, and 2 mm to 3 mm mesh gates should be installed. Before the fish species enter the pool, they must be screened and bred in size to prevent the big fish from competing for food and affecting the growth of the fish. The stocking density depends on the dissolved oxygen in water, the amount of water injected, and the size of the fish. Weight of 3 grams to 5 grams per square meter 200, water flow rate of 10 liters per second. In the first 20 days of breeding, feeding the small mung fish, the daily feeding amount is 6% to 10%, and the daily feeding is 4 times. After 20 days, the mixed feed is used, and the daily feeding amount is 2% to 4%. Feeding 4 times. In order to meet the nutritional needs of fry growth and development, in addition to feeding artificial compound feed, some live bait such as leeches and clams are also required. In the breeding process, we must pay attention to control the amount of water injection, often wash the gate, to prevent the gate jam, lack of oxygen dead fish, and often remove the pool bottom dirt bait, maintain a good environment, is conducive to the growth of fingerlings.
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