What are the precautions for farming grass carp in northern China
Grass carp is the most common aquaculture species. It grows relatively fast, has a large body size, and its meat is very delicious and tender. The farming cost is extremely low, and it is the most common species in China's fish farming industry. However, it also comes with some disadvantages, such as a high disease incidence rate and a low survival rate, which also have a great impact on grass carp yield and the economic interests of farmers. Especially in the dry and low-temperature environment of the north, what should be noted when farming in the north? Let's take a look together!
1. Pond stocking
First, prepare two ponds. One is used for trials, and the other is used for formal farming after the trials are completed. The area of the trial pond should be determined according to your own farming quantity, but the depth is generally about 1.5-2 m, and the water source is best to use reservoir water. Put fry into the trial pond according to the previous quantity, and do not exceed the range that the fish pond can bear.
2. Feeding management
Half a month before the fry are taken out of the trial pond in spring and formally put into the farming pond, dry-clean the pond once with quicklime, using about 10 kg per 70 sq m. Before putting them into the pond, at least 50 cm of water needs to be added to the pond, and new water should be added to the pond once every half month. The fry should be selected as disease-free, robust fry of uniform size. Before putting them in, it is best to soak them in salt water for a few minutes for disinfection. Use the conventional sound domestication method for feeding, so that all fish float to the surface to compete for food within 4 days.
3. Management
In the trial pond, feed with low protein and high fiber should be used together with green grass feed. The feed can use organic feeds such as green bean powder, soybean powder, fish meal, corn, and multi-vitamin mineral salts, but note that the crude protein content in the feed must be at least above 10%. Feed at least three times a day, once each in the morning, noon, and evening, with each interval within 2-4 hours. Every night, pay attention to removing the residual feed on the water surface to prevent spoilage from polluting the water quality and causing grass carp illness.
4. Water quality
The water quality of the pond must be fertile water and needs to be “fertile, lively, tender, and refreshing.” The water quality should be fresh, with a PH value of around 7 at best, and the underwater scene should still be clearly visible at a distance of at least 30 cm. After entering summer, as the temperature rises, the water temperature will also gradually rise. Therefore, in order to prevent the water from aging and deteriorating, at least 20 cm of the pond water needs to be drained and replaced with new water every half month. Keep the water quality fresh, and pay attention to recording the water temperature and feeding situation every day.
5. Disease
Because grass carp all live in water, if disease occurs it cannot be discovered in time, and sometimes it is only known when they die and float to the surface at the end. Therefore, fish diseases should mainly be prevented. In summer, under conditions of high temperature, frequent rain, and breeding bacteria, an appropriate amount of antibacterial drugs needs to be added to the feed to prevent disease. Starting in early July, quicklime should be splashed in the pond once every half month for disinfection, and the feed should also be correspondingly preserved and disinfected.
Grass carp diseases are the hardest to discover. Living in water, their condition cannot be observed in time, and it is also impossible to know whether disease has occurred. Therefore, disease is the biggest headache for the fish farming industry, and prevention work must be done well. Do a good job in pond disinfection, do a good job in frequently changing water and applying more fertilizer, reduce all possible sources of disease, lower the disease incidence rate, and improve the survival rate of grass carp.