Experience in water quality control of farmed rainbow trout

Water quality condition is an extremely important content, which is directly related to the success and failure of rainbow trout culture and production.

Rainbow trout is a fish that likes countercurrent and oxygen. The stimulation of water flow can not only accelerate the metabolism of substances in the body, but also take away excreta. The suitable flow rate for rainbow trout is 2-3 cm / s, and the amount of dissolved oxygen in water is generally more than 5 mg / L. And factory aquaculture water dissolved oxygen to reach more than 9 mg / L, when the appetite is exuberant, the growth rate is also fast.

The dissolved oxygen of rainbow trout farming in summer must avoid less than 5 mg / L, because when the dissolved oxygen in the water is less than 5 mg / L, rainbow trout develop discomfort and respiratory rate increases. When the dissolved oxygen is 3 mg / L, it can cause a large number of rainbow trout suffocation death.

Rainbow trout prefer clean and transparent water, where suspended matter falling on the gills can cause breathing difficulties and, in severe cases, suffocate. Juvenile fish are particularly sensitive to turbid water.

For rainbow trout, the optimum pH value range is pH6.5~6.9. The ability to adapt to salinity increases with the growth of individuals.

Rainbow trout culture generally adopts the method of running water and high density, so the water flow limits the scale of the culture surface. Under normal circumstances, the construction of 600 square meters of aquaculture water surface, water injection of 100 litres per second to ensure the exchange capacity of water.

Because the flow rate is proportional to the amount of dissolved oxygen in the water, the flow rate must be adjusted during the breeding period of floating juvenile fish. The flow rate should not be too large, when it is too large, the top water of fish fry will consume too much physical energy, and even die by sticking to the outlet net; too small, it can not guarantee the amount of dissolved oxygen needed for the growth and development of fish fry, so it should be adjusted according to the amount of dissolved oxygen in pond water, activities and feeding of juveniles. In general, through observation, the flow can be controlled when the fry does not stick to the gate net.

The newly floated juvenile fish have a poor ability to resist disease erosion, so the bottom of the pond must be cleaned up anytime and anywhere according to the amount of residual bait and excrement. The outlet mesh is small, so the brush net must be checked at any time every day to remove the dirt deposited on the net and ensure the smooth flow of water.

When adult fish are cultured, the highest water temperature is more than 22 ℃, which poses a threat to rainbow trout culture, so the rise of water temperature must be controlled.

Rainbow trout like clean and transparent water, pond water color should be clean and transparent, chromaticity is generally less than 30 degrees, suspended matter in the water should be less than 15 mg / L. The chemical substances in the water shall conform to the scope of the standards issued by the Ministry of Fisheries Water.

Under the condition that the water source and water environment are already available, it is necessary to make full use of the topography, cause a certain amount of water drop and flow rate, achieve the self-flow of drainage and irrigation, and reduce the water lifting power, so as to reduce the production cost.