Running water culture technology of rainbow trout

Rainbow trout gets its name because its adults have a reddish-brown longitudinal pattern along the line, like a rainbow. Rainbow trout has the advantages of delicious meat, rich nutrition, less thorns and more meat, high edible value, rapid growth, easy artificial reproduction and so on. At present, rainbow trout has become one of the four freshwater aquaculture species with high yield and good quality promoted by the Food and Agriculture Organization of the United Nations, and has been classified as high-grade fish. The living water temperature of rainbow trout is 2 ℃ ~ 25 ℃, and the optimum water temperature is 12 ℃ ~ 20 ℃. Rainbow trout has a wide adaptability. It can be cultured not only in ponds, but also in reservoirs, lakes and rivers, especially in running water. The practice of breeding in a large area has proved that the average yield of adult fish per mu is 30,000kg ~ 35000 kg, with a maximum of more than 50000 kg. Therefore, the prospect of rainbow trout aquaculture is attractive.

I. Construction and layout of fish ponds

A perfect breeding farm should have larval ponds, fry ponds, fry ponds, adult ponds, parent ponds and backup parent ponds according to different growth stages of rainbow trout. Its area can account for 0.5%, 1.0%, 12.5%, 80%, 3.0%, 3.0% of the total area, respectively, and a small number of quarantine ponds should be set up where possible to prepare for quarantine of diseased fish. The juvenile fish ponds, fry ponds and fish fry ponds are better made of stone or concrete structure, and the adult fish ponds and parent fish ponds can be either soil, stone or concrete structures. No matter what the structure of the fish pond, the determination of its shape must take into account the smooth flow, easy to discharge, give full play to the utilization rate of land and reduce the cost of the project. The layout of all kinds of fish ponds is as follows: young fish ponds, fry ponds, fish fry ponds in the front, adult fish and parent fish ponds in the back. The quarantine pond should use water alone, and the discharged water can no longer be used. According to the topography, each row of fish ponds should have a certain drop to facilitate the natural flow of water.

Every fish pond must have an inlet, a drain and a sewage outlet. The size of the inlet and outlet should be determined according to the water flow rate, flow rate, the size of the fish pond and the shape of the fish pond, the intake method, the number of times required to change water, and so on. If the direct flow water intake, drainage, nozzle width is better, in order to increase oxygen; such as spraying or pouring water into the water, the size of the nozzle should be designed according to the required flow rate, water pressure and flow rate. Fish bars should be set up at the inlet and outlet to prevent fish escape. The fish fence should be strict, and the spacing should be determined according to the size of the fish.

2. Feeding and management

The whole feeding process of rainbow trout can be divided into four stages: larval stage (from hatching to two months after feeding), fry stage (from 2 months to 6 months after feeding), fry stage (from 9 months after feeding to the end of the year) and adult stage (from January of the second year to sale).

Within 20 days after hatching, the larvae rely on the nutrition in their yolk sac to maintain their growth and development, and there are about 10,000 to 50,000 larvae per square meter. Hatch for 20 days and start feeding. At first, the hard-boiled egg yolk can be turned into syrup and dripped into the fish pond. One month after eating, you can put 500 to 1000 eggs per square meter. You can squeeze out the cooked egg yolk with gauze to make the egg yolk drop in the water. Later, the egg white can also be used together. Can also use animal liver, fresh miscellaneous fish ground into a paste, dripping into the surface of the water for feeding. Feed 6 ~ 8 times a day. The daily feeding amount can account for 12% of the body weight of fish.

After two months of feeding, the weight of the larvae has reached about 1 gram and has entered the fry stage. 200 ~ 500 larvae can be released per square meter, and all of them can be fed pellet feed. However, the animal composition in the feed should be maintained at more than 80%. The daily feeding amount can account for about 9% of the fish body weight, and the fish can be fed 4 times a day. Half a year after the start of feeding, until the end of the year, for the fish fry period, 50 ~ 200 fish can be released per square meter. Can be fed with adult fish feed, the amount of feeding can account for about 5% of the fish body weight, daily feeding times 3 ~ 4 times.

In the adult period, 15 ~ 50 fish can be released per square meter, and the water depth is 1 ~ 2 meters. In feed, animal feed accounts for 30%-40%, plant feed accounts for 60%-70%. The size of the particles is palatable, with a diameter of 4 mm ~ 8 mm, fed twice a day, and 2% or 3% of the total weight of the fish. In order to achieve high yield of adult fish, it is necessary to maintain sufficient water volume and set up oxygenation equipment in management, which should be replenished immediately in case of hypoxia. Secondly, the adult fish that have reached the edible standard should be caught and sold in time, and the individuals with obvious differences will be selected and raised in separate ponds.