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UMESC Publications

Evaluation of antifungal agents for fish culture

Marking, L. L., Rach, J. J., and Schreier, T. M., 1994, Evaluation of antifungal agents for fish culture: The Progressive Fish Culturist, v. 56, no. 4, p. 225-231.

Abstract

The antifungal activities of 21 chemicals against species of Saprolegnia, a ubiquitous genus of aquatic fungi frequently found in fish hatcheries, were evaluated with pure fungal culture and with Saprolegnia-infected eggs of rainbow trout (Oncorhynchus mykiss). Fourteen compounds were ineffective for control of fungus on rainbow trout eggs or were toxic to the eggs. The seven compounds that effectively controlled fungus on infected eggs and provided a reasonable margin of safety were Abbott A-73336, amorolfine, formalin, glutaraldehyde, hydrogen peroxide, melaleuca, and salt (sodium chloride). Only formalin, hydrogen peroxide, and salt appeared completely suitable for registration. Formalin, the replacement antifungal agent, is restricted to use with the eggs of salmonids and esocids. User safety and the effect of effluents on the environment are also concerns related to formalin treatments. Formalin effectively prevented fungal infections on eggs at concentrations as low as 250 ppm. A 1,000-ppm treatment of formalin not only prevented infection but also decreased existing infection and increased hatching rates at exposures of 15, 30, or 60 min. Hydrogen peroxide at concentrations of 500 and 1,000 ppm controlled fungus on infected eggs and increased hatching rates of treated eggs. Hydrogen peroxide was recently classified by the U.S. Food and Drug Administration as a low regulatory compound when used to control fungi on all species and life stages of fish, including eggs, and it is the antifungal agent of choice for further development. Salt decreased infection level and increased hatching rate of infected eggs at a concentration of 30,000 ppm. Salt is readily available and listed as a low regulatory compound, but the large quantities required limit its applicability.

Keywords

fungal-diseases, disease-control, fungicides-, comparative-studies, fish-culture, toxicity-tests, lethal-limits, fish-eggs, Saprolegnia-, Oncorhynchus-mykiss, fish-diseases, freshwater-aquaculture, antifungal-agents, aquaculture-