Not Available

The work was carried out under“All India NetworkProject on Fish HealthInfection withAphanomyces invadansis a serious disease affecting freshwater and brackishwaterfish. Even after50 years of itsfirst occurrence, to date, there is no effective treatment for this disease. To develop an effectivetreatment against this disease, in the current study, we have evaluated the potential of six commonly usedchemicals and drugs with known antifungal properties against different life-stages (zoospore production, ger-mination of zoospores and growth of hyphae) ofA. invadans. The chemicals namely formalin, potassium per-manganate (KMnO4), hydrogen peroxide (H2O2), sodium thiosulphate (Na2S2O3) and drugs including ampho-tericin B andfluconazole were evaluated in a dose-dependent manner (0.1, 1.0, 5, 10 and 100 ppm) underinvitroconditions. Out of the chemicals tested, formalin could completely inhibit zoospore production and sig-nificantly inhibit germination of zoospores and growth of hyphae at 10 ppm, however, complete inhibition ofzoospore germination and growth of hyphae could only be observed at 100 ppm. In the case of H2O2, there wassignificant inhibition of germination of zoospores and growth of hyphae at the highest concentration of 100 ppm,but it could not completely inhibit zoospore production, germination of zoospores and growth of hyphae. KMnO4at the highest tested concentration (100 ppm), completely inhibited zoospore production and significantly in-hibited germination of zoospores and growth of hyphae. Na2S2O3was found to be ineffective against all the threelife-stages ofA. invadanseven at the highest tested concentration of 100 ppm. Out of the two antifungal drugs,fluconazole could reduce the germination of zoospores and growth of hyphae significantly at a dose of 1 ppm. Onthe other hand, in the case of amphotericin B, significant inhibition of germination of zoospores and growth ofhypahe was observed only at 100 ppm. Both drugs completely inhibited zoospore production only at 100 ppm.From thefindings of the present study, it can be inferred that out of the six compounds, formalin andfluconazolehave better anti-oomycete effects underin vitroconditions. The information generated would serve as a basis fordeveloping treatment measures against infection withA. invadansin aquaculture pondsIndian Council ofAgricultural Research is duly acknowledge