What stocking density per mu is suitable for farming the Four Major Chinese Carps?

AbstractThe Four Major Chinese Carps refer to grass carp, bighead carp, silver carp, and black carp. Among them, the stocking density of grass carp is about 1,200 fish per mu, bighead carp about 50 fish per mu, silver carp about 300 fish per mu, and black carp about 300 fish per mu.

1. Stocking density per mu for the Four Major Chinese Carps

China's Four Major Chinese Carps are very common in natural waters and are suitable as food fish for the general public. They refer to grass carp, bighead carp, silver carp, and black carp.

1. Silver carp: It mainly swims in the upper layer of the water and feeds on phytoplankton such as green algae. Its stocking density is about 300 fish per mu.

2. Bighead carp: Because of its very large head, it is called the fathead fish, also known as spotted silver carp. It lives in the middle and upper layers of the water and mainly eats zooplankton. Its stocking density is about 50 fish per mu.

3. Grass carp: It mainly lives in the middle and lower layers of the water. It eats aquatic vegetation, excretes it, and then eats it again after the excrement produces microorganisms; when eating, it filters out the microorganisms inside. Its stocking density is about 1,200 fish per mu.

4. Black carp: It lives in the lower layer of the water and mainly eats mollusks such as snails and mussels. Its stocking density is about 300 fish per mu.

2. Water quality management for farming the Four Major Chinese Carps

1. Change the water at the right time

After a certain period of farming, the fish pond needs to have its water changed. Especially when water quality gradually deteriorates, 20-30cm of old pond water should be pumped out and new water added at the same time, so that the organic matter in the water is diluted. However, do not add too much new water at one time, to avoid damaging the water environment and causing stress reactions.

2. Apply zeolite powder

The usual amount of zeolite powder is 30-50kg per mu. The specific amount depends on the actual situation, such as the degree of water pollution. Applying an appropriate amount of zeolite powder can, on the one hand, increase oxygen, and on the other hand, degrade part of the organic matter in the water, thereby reducing water pollution.

3. Apply probiotics

(1) After applying zeolite powder, apply probiotics immediately afterwards. Probiotics contain a large number of photosynthetic bacteria, HEM, and others that can help the Four Major Chinese Carps form a better growth environment, decompose harmful substances, and inhibit the reproduction of pathogens. At the same time, they leave little drug residue, making the food safer.

(2) The amount of probiotics used each time is 1-2kg per mu. After application, be careful to avoid using disinfectants again and reduce the frequency of draining and changing water, so as to avoid waste.

4. Drug disinfection

Regular disinfection can also, to a certain extent, improve water quality and prevent diseases in the pond, but at the same time disinfectants also bring certain side effects, such as killing part of the plankton, thereby disrupting the ecological balance of the entire water environment. The disinfectants generally used on the market are mainly chlorine dioxide preparations, organic iodine preparations, and bromine preparations. Their effect is higher than that of bleaching powder. Be careful not to use too much, otherwise it will instead reduce the fish's own resistance.

5. Apply quicklime

When abnormal phenomena such as rainfall, the pond water becoming darker, or low visibility occur, 15-30kg of quicklime can be applied. It can both regulate water color and maintain buffering capacity.

6. Polyculture of filter-feeding fish

Filter-feeding fish such as silver carp and bighead carp mainly feed on algae in the water. They can increase the consumption of ammonia nitrogen and organic debris in the water, effectively improve water quality, and increase transparency.

7. Mechanical aeration

Aerators can increase oxygen, stir water, and aerate. Through lifting, exchange, and circulating flow, they promote the oxygen content in the water and reduce the feed conversion ratio, which is beneficial for promoting the growth and development of the Four Major Chinese Carps. They are commonly used in freshwater aquaculture.

In addition, water circulation also promotes the distribution and reproduction of plankton, improves productivity and the ability to absorb ammonia nitrogen, nitrite, and others, and improves water quality and the environment. For ponds with a yield of more than 250kg per mu, configure aerator power of 0.25-1KW per mu. If conditions permit, installing multiple aerators gives better results.

8. Drug-based oxygenation

When the Four Major Chinese Carps show gasping at the surface, it indicates that water quality has deteriorated. In an emergency, an appropriate amount of hydrogen peroxide, calcium peroxide, and high-efficiency oxygen-increasing agents can be applied to supply oxygen to the fish, but do not become dependent on them. The fundamental solution to water quality problems cannot be achieved overnight; the above methods should also be adopted to maintain management step by step.