What should be noted in mandarin fish farming? Water quality regulation and stocking density are key
AbstractDuring mandarin fish farming, attention should be paid to water quality regulation and stocking density, and filter-feeding fish can be polycultured to maintain the energy cycle of the pond. Fry are easily damaged during transport, so cultivating seedlings yourself can ensure the survival rate. Pesticides should be used rationally, reducing the use of irritating drugs to avoid mandarin fish being infected with diseases due to decreased resistance.
1. Reasonable polyculture
Mandarin fish feed on live bait. While ensuring the normal stocking density of mandarin fish, a certain number of bait fish also need to be polycultured, which easily leads to an excessive fish carrying capacity in the pond, with correspondingly larger amounts of feces and residual bait. Therefore, during production, a certain number of silver carp and bighead carp can be appropriately polycultured as filter-feeding fish to maintain the normal material and energy cycle in the pond, providing a good water quality environment for mandarin fish to grow healthily.
2. Pay attention to water quality regulation
Mandarin fish like to live in lakes and reservoirs with clean water quality. Mandarin fish feed on live bait. After farmers stock them at high density, the metabolic areas of mandarin fish and bait fish increase, the amount of plankton in the water is relatively small, primary productivity is not high, and the material and energy cycle is not smooth, so residual bait and feces cannot be promptly converted into nutrients usable by algae, causing metabolic products to continuously accumulate and breeding a large number of pathogenic microorganisms, harming the growth and health of mandarin fish.
Therefore, during farming, the aquaculture water body should maintain vigorous algae, and the water color should remain light green. Keeping the water environment stable can reduce the incidence of viral diseases. At the same time, attention should also be paid to reducing the use of chemical fertilizers such as urea and ammonium bicarbonate to fertilize water quality.
3. Reasonable stocking density
At present, mandarin fish farming methods in Jiangsu, Zhejiang, and Guangdong mostly use pond monoculture. To improve economic benefits, some farmers often adopt high-density farming, which increases the density of bait fish, increases the load on the aquaculture pond, increases metabolic products, and accumulates large amounts of harmful substances such as ammonia nitrogen, leading to deterioration of the pond water quality environment and harming the health of mandarin fish. Generally, the stocking density of mandarin fish about 3cm is 1.5-2025 ten thousand fish/hm2. Excessive stocking density will increase the incidence of viral diseases in mandarin fish.
4. Seedling cultivation
Most mandarin fish seedlings on the market come from Guangdong. It has been found that mandarin fish seedlings above 2.5cm on the market are prone to diseases such as ciliates, Chilodonella, and Trichodina during cultivation, and Guangdong also mostly uses irritating drugs such as formalin for prevention and control, increasing the chance of mandarin fish suffering from viral diseases.
It is recommended that farmers can purchase mandarin fish seedlings of 1.8-2.5cm specifications according to actual conditions for cultivation, which can both reduce costs and ensure the survival rate during transport. More importantly, during the seedling stage, prevention and control work for diseases such as Trichodina, Chilodonella, and Dactylogyrus can be carried out more scientifically.
5. Palatable bait
After the peak feeding period of mandarin fish, catch healthy mandarin fish for inspection. Cutting open the stomach of mandarin fish, two or three bait fish can be seen, indicating that the specifications of the matching bait fish are suitable. Any fish without hard spines, with low price, slender body shape, wide sources, high population yield, and suitable for high-density farming can be the first choice as bait fish for mandarin fish, such as mud carp and silver carp.
6. Medication contraindications
Long-term abuse of drugs in aquaculture ponds can cause white liver symptoms in mandarin fish. Mandarin fish are very sensitive to most drugs, especially heavy metal salts, halogen chemical disinfectants, organophosphorus insecticides, etc.
Farmers are easily misled by prevention and control methods in books and use irritating drugs such as bleaching powder, copper sulfate, and strong chlorite too frequently during disease prevention and control. Although these drugs can kill insects and bacteria, because of their strong corrosiveness, they easily destroy the mucus protective layer on the body surface of mandarin fish and cause inflammation of the gill tissue of mandarin fish, affecting normal breathing and thereby causing fish deformities.
Moreover, the use of highly irritating drugs has a strong killing effect on plankton in the water body, causing adverse effects on mandarin fish feeding, thereby leading to decreased resistance and infection with diseases in mandarin fish, causing bacterial gill rot in mandarin fish.