COMPARATIVE EFFECTS OF VARIOUS ANTIBIOTICS, FUNGICIDES AND DISINFECTANTS ON APHANOMYCES-INVADERIS AND OTHER SAPROLEGNIACEOUS FUNGI

Fifty-four isolates of various fish-pathogenic and saprophytic fungi w ere characterized in terms of their susceptibility to three antibiotic s (penicillin, streptomycin and oxolinic acid), three fungicides (mala chite green, hydrogen peroxide and sodium chloride) and three disinfec tants (an iodophore, sodium hypochlorite and a solution of peracetic a cid and hydrogen peroxide). Aphanomyces invaderis, the fungus associat ed with the Asian fish disease epizootic ulcerative syndrome (EUS); ot her Aphanomyces isolates from the similar conditions redspot disease ( RSD) and mycotic granulomatosis (MG); and the crayfish plague fungus, Aphanomyces astaci, were more sensitive to most of the chemical agents than the other fungi tested. Two compounds currently being considered for use in aquaculture, hydrogen peroxide and Proxitane 0510, are sho wn here to have some potential for fungicidal treatments and disinfect ion, respectively. The implications of this study with respect to the isolation, treatment and control of A. invaderis are discussed.