Description of Protozoan Parasites Parasitizing Gold Fishes and Their Possible Control by Herbal Extracts

Abstract

Disease outbreak due to infection by protozoan parasites is a limiting factor behind successful aquaculture. A parasitological survey of most economically important Carassius auratus ornamental fish farms of West Bengal, India, revealed the invasion of different ectoparasites belonging to the group myxozoa and ciliophora. During the study, parasites like Myxobolus sp., Thelohanellus sp., Trichodina sp. and Tripartiella sp. were found at the body surface, tail fin and gill regions of the fish. The parasitic infections were prevalent mostly during the post-monsoon season. Use of a wide variety of drugs and chemicals not only makes the environment unfavourable for aquaculture but also renders the pathogen resistance towards them over time. Hence, alternative therapeutic strategies for controlling the parasitic ciliates were made in this study by using herbal extracts of Swietenia mahagoni (Mahogany) and Cinnamomum tamala (bay leaf). After determining its toxicity level (LC50 value—11.39 g for mahogany and 15.05 g for bay leaf), 8 g/Kg extract of Swietenia mahagoni was found to reduce the trichodinid ciliates burden of ornamental fish significantly (P < 0.01) within only 5 days, whereas bay leaf extract takes 15 days, which is too time-consuming. This study clearly demonstrated that the mahogany plant extracts show strong antiprotozoan activities.