Abstract:
Centrocestus formosanus (Nishigori 1924) is a trematode parasite introduced into many parts of the world through the aquarium fish trade. Its infection causes high fish mortalities and economic losses to fish farmers worldwide. In this study, the efficacy of ethanol (95%) extract of Anacardium occidentale (Linnaeus 1753) apple to control C. formosanus infection in Xiphophorus hellerii (Heckel 1848) was investigated. According to Probit analysis, the estimated 96 h LC50 of plant extract for X. hellerii was 387.28 mgL-1. Infected X. hellerii was treated with concentrations of 300, 320, 340, 360, and 380 mgL-1 plant extract with exposure periods of 24 and 48 h. The behavior and mortality of treated and non-treated fish were observed for two weeks. Mortality and parasitic intensity of treated fish were significantly lower than that of non-treated fish during the experiment and recovery period. The parasitic intensity in treated fish decreased significantly with increasing concentration of plant extraction in 24 h and 48 h exposure. The lowest dose of A. occidentale apple extract needed to reduce more than 70% of metacercariae infected to gills of X. hellerii within 24 h was 340 mgL-1. According to the findings, A. occidentale apple extract can effectively control C. formosanus infections in aquarium fish.
