Control Methods for Fusarium Disease in Shrimp Farming

(1) Pathogen: The Fusarium species include Fusarium solani, Fusarium oxysporum, Fusarium tricinctum and Fusarium graminearum. The fungal body is filamentous and branched, often with septa. Reproduction occurs by forming macroconidia, microconidia and chlamydospores. The macroconidia are sickle-shaped, hence the name Fusarium.  

(2) Symptoms: Fusarium mostly parasitizes the tissues of diseased shrimp in the branchial region of the carapace, appendages, body wall and eyeballs, and the parasitized tissues appear black due to melanin deposition. When parasitizing the gills, it causes necrosis and blackening of the gill tissue. Some call this “black gill disease”.  

(3) Diagnosis: Since the main symptoms of Fusarium disease are often similar to brown spot disease and black gill disease caused by bacteria, samples must be taken from the lesions and observed under a microscope; if hyphae and their conidia are found, a confirmed diagnosis can be made.  

(4) Epidemiology: This disease is highly harmful to shrimp and crabs. In seawater, various shrimp, lobsters and crabs can all be infected, with an infection rate as high as 70% and cumulative mortality of 90% (such as California shrimp in the United States). In China, it currently occurs mainly in artificially overwintered brood shrimp. It is relatively rare during shrimp disease prevention and control periods.  

(5) Prevention and control: 1. Before stocking, disinfect with 6.0×0.000001 sodium dichloroisocyanurate, which can effectively kill conidia in the pond. 2. Before brood shrimp enter the overwintering pond, wash them with 300×0.000001 potassium permanganate for 5 minutes, and strictly prevent injury to the shrimp body. 3. Use disinfected and filtered water sources free of Fusarium contamination to cultivate brood shrimp.