How to prevent and treat trichodiniasis in yellow catfish farming?

[Cause] The pathogens are Trichodina and Trichodinella. They spread through direct contact, or the trichodinids leave the fish and swim freely in the water to move to new hosts.

[Symptoms] The pathogens mainly parasitize the gills, body surface skin and fins of yellow catfish. With a light infestation, the yellow catfish feed and move normally; with a heavy infestation, it easily causes mucus hyperplasia on the gills and skin, congestion of the gill filaments, and small bleeding spots on the body surface skin, along with reduced appetite. When feeding, the fish gather downstream of the feeding table, do not come up to feed, or scatter in groups when they do come up to feed. The fish body color darkens, the fish become emaciated and tend to rub against the pond edge or pond bottom. It generally does not cause death.

[Prevalence and harm] April to July is the main epidemic season for this disease, and the suitable breeding temperature for Trichodina is 20 to 28 degrees. The main targets of harm from this disease are fry and fingerlings. When water quality deteriorates and stocking density is too high, outbreaks occur very easily and spread, which can cause mass mortality of fish.

[Diagnosis] Scrape the body surface or fins of the yellow catfish, or take gills to make a wet mount slide; a large number of trichodinids found under microscopic observation confirms the diagnosis.

[Prevention] (1) Carry out pond clearing before stocking, and maintain good water quality. Choose a reasonable stocking density. (2) Before stocking fingerlings, soak them in 3% salt water for 5 minutes.

[Treatment] Splash the whole pond with a mixture of 0.5 mg/L copper sulfate and 0.2 mg/L ferrous sulfate, once every 3 days, for 2 to 3 consecutive treatments, which can effectively prevent and treat this disease.