Key Technical Points for Disease Prevention and Control in Pollution-Free Black Carp Pond Aquaculture

1 Preventive measures

Adhere to the principle of early prevention of disease-free fish, early treatment of diseased fish, with prevention taking priority over treatment.

1.1 Pond cleaning and disinfection;

1.2  Fry disinfection;

1.3  Feed disinfection

The feed fed should be fresh, clean and hygienic. After washing snails and clams, select fresh and live ones for feeding; soak green feed in 3mg/L to 5mg/L bleaching powder solution for 20min to 30min; add or spray liver and gallbladder rehabilitation agents and vitamin C to compound feed to prevent black carp hepatobiliary syndrome.

1.4  Feeding ground disinfection

a) Generally, disinfect with bleaching powder 1 to 2 times a month, using 250g of bleaching powder each time, dissolved in 12.5kg of clean water, and splash it at the feeding ground;

b) During the fish disease epidemic season, use medicine hanging bags and hanging baskets for prevention. Each feeding ground can hang 3 to 6 baskets (bags), each containing 40g to 60g of bleaching powder, change the medicine once a day, for 3d each time;

1.5 Fishing gear disinfection

Fishing gear used in diseased ponds should be exposed to sunlight for 1d for disinfection, or soaked in a 300mg/L potassium permanganate solution, or soaked in a 10mg/L copper sulfate solution for 30min;

During operations such as pond splitting and transport, care should be taken to avoid fish body abrasions and frostbite, which can induce saprolegniasis.

2 Prevention during the fish disease epidemic season

At the end of April and beginning of May and from September to October, during the fish disease epidemic season, splash 90% crystal trichlorfon solution over the whole pond at a dosage of 330g per mu of pond with 1m water depth, to prevent and kill parasites such as anchor worms and Sinergasilus. After 2d, splash a chlorine-containing preparation over the whole pond once to prevent secondary bacterial infection. Chlorine-containing preparations can be selected from: bleaching powder, dichloroisocyanuric acid, trichloroisocyanuric acid, chlorine dioxide, dibromohydantoin, etc., and the dosage should refer to the product instructions. From mid-May to the end of August, twice a month, alternately splash quicklime and chlorine-containing preparations over the whole pond to prevent bacterial diseases such as enteritis and gill rot. The dosage of quicklime is 15kg to 20kg per 667m2 of pond with 1m water depth, and the use of drugs shall be implemented in accordance with the provisions of NY5071-2001.