CATDOLL : CATDOLL: How big can rainbow trout grow?

How big can rainbow trout grow?

The largest rainbow trout can grow to about 40 centimeters and weigh about 8 kilograms. Rainbow trout is a cold-water pond-raised fish of the genus Pacific salmon in the family Salmonidae. It is the most important cold-water fish that is widely farmed in the world.

Is rainbow trout easy to raise?

Rainbow trout is a valuable cold-water edible fish, and it also has a high breeding value. It is an important agricultural aquaculture project. When breeding, it is necessary to carry out reasonable feeding and management according to its living habits. So, is rainbow trout easy to raise? Let's learn about the rainbow trout breeding methods below.

I. Methods of breeding rainbow trout 1. Breeding trout in ponds with high-density water flow This is a breeding method currently widely used both at home and abroad. It has the advantages of small footprint, saving manpower and material resources, high bait utilization rate, and high yield. 2. Breeding trout using deep, low-temperature water in high-dam reservoirs. The water temperature of high-dam reservoirs varies in direct proportion to the water depth, with high surface water temperature and low bottom water temperature. Using deep, low-temperature water output from high-dam reservoir power generation or irrigation tunnels, trout can be raised in cages in the downstream channels near the reservoir. This article will take the Zhejiang Xin'anjiang rainbow trout breeding farm as an example. (1) Breeding situation. 20 kilometers downstream of the Xin'anjiang Reservoir Dam, there is sufficient flow, and there are many aquatic plants, small fish and shrimps. In recent years, the number of warm-water fish living there has been decreasing, but breeding rainbow trout has unique conditions. In January 1980, the Fisheries Administration of Jiande County, Zhejiang Province, imported 30,000 eyed rainbow trout eggs from Taiyuan for local hatching, and a total of 10,500 fry were hatched. On April 5 of the same year, they were moved outdoors and transported to the river 3 kilometers downstream of the Xin'anjiang Dam for breeding in cages. The water temperature at the breeding site was between 9℃ and 20℃, with a monthly average temperature variation of 10.3℃ and 16.2℃. The flow rate was 0.2 meters per second when the water flow was urgent. During the cage breeding process, 6,000 fry accidentally escaped into the river. As of December, 4,500 fry were kept in cages, with an average weight of 75.7 grams. As of November 1981, more than 4,000 adult fish were grown, with an average weight of 880 grams. As of December 1983, the average weight was 2,400 grams. (2) Cage specifications and stocking density. ① Broodstock cages. The specification is 4m×4m×1.7m, the area is 16m2, the volume in water is 24m3, the mesh is 4.5cm, and it is woven with 3×4 polyethylene wire. The stocking density is 10 per square meter and 6 per cubic meter. A 9cm mesh is used as the cover net. The mesh of the parent fish cage is larger, mainly considering that small fish can enter the cage and can be used as rainbow trout bait. ② Adult fish cage. The specification is 4m×4m×1.7m, the area is 16m2, the volume in water is 24m3, the mesh is 3cm, and a 6cm mesh is used as the cover net. The nets are all woven with 3×4 polyethylene wire. According to the test in 1981, the stocking density is 100 and 63 per square meter, which has little difference in the growth rate and survival rate of adult fish. In 1983, 125 per square meter were stocked, and the size of the fish entering the cage was above 50 grams. ③ Fingerling cage. Fingerling cages are divided into two levels. The first-level fish cage has a specification of 2 meters × 2 meters × 0.7 meters, an area of ​​4 square meters, and a water volume of 1.6 cubic meters. It is made of a 16-mesh polyethylene wire mesh per square meter to form a closed hexahedron, leaving one edge unsewn as the feeding port. The first-level cage is used to stock fish species under 11.5 cm, with a stocking density of 2,500 per square meter. When the fish grow to more than 11.5 cm, they are moved to the second-level fish cage. The second-level cage has the same specifications as the first-level cage, made of a mesh with a mesh size of 1.5 cm, and a stocking density of 400 per square meter. This design of the fish cage is mainly based on the consideration that the mesh size is small and is easily blocked by green moss. This style is made to facilitate turning the cage in the water. The bottom of the cage is used as a cover, and the green moss falls off after being exposed to the sun, which can also prevent bird damage. In case the cage sinks into the water, it can also prevent fish from escaping. The cages are all made of bamboo frames and are floating. (3) Bait. The trout feed at the Xin'anjiang Rainbow Trout Farm is made from cheap local pig blood, mainly pig blood and wheat bran, with fish meal, aquatic plants, etc. The feed system for the fingerling stage is 2.74, and the feed system for the adult stage is 3.05. Adult fish and broodstock are fed twice a day, and the feed cost for each net increase of 0.5 kg of fish is 0.66 yuan. 3. Transplantation and release of rainbow trout in mountain streams and rivers. Rainbow trout originates in mountain streams and mainly feeds on insects and small fish. Most of the fish in mountain streams are small fish with low economic value. If rainbow trout are transplanted and released into such waters, they will not spread arbitrarily due to the limitation of their own living water temperature threshold, thus achieving the effect of converting low-level fish into high-level fish. In 1983, the Sichuan Water Resources Department began to conduct transplantation and release experiments of rainbow trout in Dahaizi and Jiulongzhai Nature Reserve in Minjiang River. 4. Raise rainbow trout in seawater cages. In recent years, the development of trout farming in seawater cages has been rapid. In 1982, Norway raised about 400 tons of trout in seawater, France about 700 tons, and Denmark, Japan and other countries also popularly raised trout. The cages used are 10 meters × 10 meters × 10 meters, 7 meters × 7 meters × 3.5 meters, etc. The stocking density is 4-5 kilograms per cubic meter, and the production is 15-20 kilograms per cubic meter. The breeding period is mostly from October to June of the following year, and it comes to an end when the seawater temperature reaches above 18°C. Denmark's seawater cage farming generally releases 200 grams of rainbow trout in April, and grows to 2-3 kilograms in January of the following year. North Korea has also succeeded in domesticating and raising trout in seawater, and it only needs to be surrounded by wire mesh or ordinary fishing nets at the seaside. In 1983, Linqu County, Changdao Island and Dalian Aquatic Products Company in Shandong Province of my country also carried out experiments on raising trout in seawater fields. According to the experiment, the growth rate of rainbow trout in seawater is 1.5 times faster than that in fresh water. 2. Requirements for rainbow trout farming 1. Uneven growth of rainbow trout is a common phenomenon. Screening should be carried out once a month. The fish should be graded and raised to improve the farming efficiency. 2. When the water temperature rises in summer, the depth of the cage should be deepened and the breeding density should be reduced to increase the activity space of rainbow trout. Inspect the cage every day, measure the water temperature, record the amount of feed fed and the feeding situation of the fish, and remove sick and dead fish in time; when there is strong wind, the cage can be lifted immediately after the wind stops to check whether there is any damage to the cage. If found, repair it immediately, and re-tighten the wire and clamp screws connecting the cages to ensure that each connection is firm. 3. Always pay attention to the changes in the water level in the breeding area. As the water level rises or falls, the iron anchors and wire ropes at the four corners of the fixed operating platform should be retracted and released in time. It is easy to produce attachments around the box, which hinders the exchange of water. When more attachments are found, the net should be lifted and cleaned immediately. The operation should be light and slow, and do not use too much force, otherwise it will scratch the surface of the fish and cause disease. 4. Disease prevention and control Rainbow trout is generally not prone to disease. Common diseases include fin rot and nutritional diseases, which usually occur in early spring. In early spring, as the water temperature gradually rises, the breeding density should be appropriately reduced, the fish should be screened and divided into boxes in time, and the operation should be careful to reduce the infringement of fish and human damage. 5. In early spring, adding an appropriate amount of medicine to the feed every week can improve the immunity of the fish and effectively prevent the occurrence of fin rot. If a fish with fin rot is found, it should be immediately removed and bathed in potassium permanganate solution and raised separately to prevent infection. Nutritional diseases are mainly caused by feeding unqualified feed. As long as the feed is fresh and nutritious, the occurrence of the disease can be prevented. As long as prevention is done in advance. Through the above introduction to whether rainbow trout is easy to raise, we now know the breeding methods of rainbow trout. Rainbow trout is a cold-water fish, and the growth and development of individuals will also vary. In the process of rainbow trout breeding, attention should be paid to daily management and disease prevention and control, scientific breeding, and normal development of rainbow trout should be ensured.