Technical points of safe overwintering of fish species to avoid economic loss

Fish farm

The safe overwintering of fish species is an important work in fish production in northern China. Serious weight loss and mass death of fish often occur during the overwintering period, which seriously restricts the development of pond aquaculture in the north. Therefore, it is very important to master the technology of safe overwintering of fish species.

1. Strengthen the pre-winter breeding of fish: although the metabolic level of fish is low during the overwintering period, it still consumes part of the energy, which mainly depends on the fat and protein stored in the fish. Frail fish species have little body fat and can not resist frost injury and fish disease and die. Before overwintering, baiting should be persisted until overwintering in parallel ponds, mainly by feeding concentrate feed containing more fat and protein.

two。 Choose a good overwintering pond: the average water depth of the overwintering pond is 1.5 ~ 3 meters, the bottom is flat, the silt is not more than 20 centimeters, there are no water plants or a small amount of water plants, no leakage, no industrial sewage inflow, the area depends on the number of fish species, 3-5 mu is appropriate.

3. Timely hoarding: the density should be appropriate. The time for hoarding and raising overwintering fish species should be appropriate, too early, the water temperature is too high, the fish species swim actively, have not stopped eating, the density of overwintering pond fish species is high, can not eat enough food, so that the survival rate is reduced. Too late, the water temperature is low, it is not convenient to pull the net, and the fish is prone to frostbite. The water temperature of overwintering pond should be about 10 ℃, not lower than 8 ℃. The density of hoarding fish species should be appropriate, the density is too high, even if the temperature is low, there will be floating heads, resulting in death. Generally speaking, the hoarding density should be determined according to the size of fish, the type of fish, the size of water surface and other conditions. The fish is bigger and thinner, and the fish is smaller and denser. Common carp and crucian carp are denser, blunt snout bream and silver carp are sparse.

Grass carp, herring, bighead carp control the general density, 15 centimeters of fish species per mu of water no more than 8000, 11 centimeters of fish species per mu of water no more than 25000, 8 centimeters of fish species per mu of water can not exceed 40000.

4. Classified according to the specifications: different physique, different sizes of fish species should not be mixed together, otherwise poor physique, small fish species will be forced to a bad environment, resulting in death. When merging ponds, fish species should be classified and stored separately, and weak fish species should be hoarded in special ponds.

5. Strengthen the management of overwintering: pay attention to baiting and maintain water quality. Often patrol the pond, observe the activity of fish species, and pay attention to the phenomenon of dead fish and floating head. Conditional grass rope or white thread can be used to pull back and forth in the pond to prevent birds from pecking and eating fish. Pay attention to adding water and fertilizer. Whenever the water temperature is above 10 ℃ at noon on a sunny day, a small amount of feed or appropriate amount of manure should be applied to keep the water quality fat and tender.