Rainbow trout is one of the most widely farmed fish species in the world. Since rainbow trout is most suitable for artificial intensive farming and has the characteristics of high yield, high efficiency and broad market, rainbow trout farming has developed rapidly, with the farming area and output increasing year by year.
1. Basic knowledge of rainbow trout biology
Understanding the biology of rainbow trout is very helpful for us to carry out scientific feeding and management of rainbow trout. Rainbow trout is a cold-water fish that usually inhabits rivers and streams with clear, pollution-free water and gravel bottoms. Rainbow trout like to live in water with a water temperature of 8-20℃. Under artificial intensive care conditions, the optimal water temperature for growth is 12-18°C. When the water temperature is lower than 7°C or higher than 20°C, appetite is significantly reduced, growth is slowed, and disease resistance is weakened. When the water temperature reaches 24°C, food intake is stopped. It can die within a short period of time at 26°C. Therefore, the upper limit of water temperature for rainbow trout under artificial breeding conditions is 24°C. Rainbow trout has no obvious lower temperature limit for growth. As long as the water does not freeze, it can feed and grow, but the feeding intensity will be weakened and the growth will be slow.
The dissolved oxygen requirement in the water body for raising trout is above 5 mg/L. When the dissolved oxygen is above 5 mg/L, the fish’s breathing rate accelerates and they feel uncomfortable. When the dissolved oxygen is above 4 mg/L, hypoxic symptoms will appear. Often causes death. When the dissolved oxygen is 3 mg/L, a large number of deaths will occur. The pH value of the breeding water body should be maintained at 5-9, the alkalinity is 1.5mg.n/L, and the hardness is 8-12. Rainbow trout has a wide adaptability to salinity, and after a short period of acclimatization, it can be cultured as adult fish in seawater.
2. Water for trout farming
Water is a prerequisite for rainbow trout farming. The water for farming should be flowing cold water. The water temperature should be below 22°C all year round and should not freeze in winter. The water quality must meet the water standards for fish farming and be clear and pollution-free. Such water source programs include mountain springs, mountain streams, underground water inflows, bottom drainage of reservoirs, melted water from snow mountains, etc.
The water used to raise trout must have a certain flow rate. Usually, the number of fish that can be raised is calculated based on the water flow rate. Generally, the yield of trout raising is about 50-200 kilograms with a flow rate of 1 liter of water per second. The water in the flowing pool should have a certain flow rate, generally between 1.2-1.8 meters/minute. The flow rate of the water for raising juvenile fish should be smaller, and the flow rate of the water for raising fish and broodstock should be slightly higher.
Rainbow trout is native to the Pacific coast of North America. It requires high living conditions and is a delicate fish species. The body of the fish is very graceful and well-proportioned, with a clear rainbow-like mark on one side of its body, which is where its name "rainbow trout" comes from. Rainbow trout have very high requirements for water temperature, and will grow and deform if it exceeds 10’C. They also grow slowly, with one fish weighing about 500 grams taking a year, so the meat is extremely delicious.
Beijingers usually go to Huairou to eat rainbow trout in the wild. Huairou’s unique water resources are suitable for rainbow trout to survive. Rainbow trout breeding has developed rapidly, with an annual output of one million kilograms of rainbow trout. Every weekend, many city dwellers drive into the rainbow trout ditch in Huairou to experience the fun of fishing and tasting rainbow trout by the lake at the foot of the mountain. It is said that an average of more than 300,000 Chinese and foreign tourists come to Huairou every year for the rainbow trout. Even in the off-season of winter tourism, many tourists visit. Rainbow trout is widely distributed in Huairou. There are more than 20 tourist attractions. There are rainbow trout fishing parks and catering facilities around almost every scenic spot. Even the Diaozi, Liuli Temple, Tanghekou and Diaogoumen in the deep mountainous areas are no exception. . The price of 500 grams of rainbow trout is usually around 20 yuan. You can also go to the Xiangshui Lake area. There are restaurants selling rainbow trout here one after another. You can hold a fishing rod and fish for rainbow trout, or you can directly pick the fish with a hook and then have a game barbecue. If you are impatient, go directly to Xiangshui Villa in the scenic area to try rainbow trout and other snacks. The fried rainbow trout here tastes very authentic and is a must-try. Snacks include beige, meat cakes, oatmeal noodles, etc.
Rainbow trout and salmon both belong to the family Salmonidae. They originate from mountain streams in California, USA. They are one of the most widely cultivated fish species in the world today.
It is a rare salmon fish and one of the rare high-grade fishes. The meat is fresh and tender, delicious, no fishy smell, no small bone spurs, high protein and fat content, almost zero cholesterol, and IPA (unsaturated fatty acid) content. Several times higher than other fish, it has good medicinal and edible value, and has become one of the new species in the current freshwater aquaculture industry