BEHAVIOURAL EFFECTS OF ANABAS TESTUDINEUS (BLOCH 1792) TOWARDS SUBLETHAL PARAQUAT EXPOSURE

A 96 hours acute toxicity test was completed in order to determine paraquat lethal concentration 50% (96H LC50) value towards Anabas testudineus. The fish was subjected to 0, 5, 10, 20, 30 and 40 mgL-1 of paraquat under laboratory conditions. Fish mortality rate was directly proportional to paraquat concentration with a total 100% mortality recorded at 30 mgL-1 in 48 hours. The 96H LC50 value of paraquat was 16.81 mgL-1 which is slightly toxic according to United States Fish and Wildlife Service. Regarding behavioural study, a 48 hours sublethal toxicity test was carried out with 2, 5, 12, and 15 mgL-1 of paraquat. Exposed fish exhibited agitated, respiratory distress and abnormal nervous behaviours which were the earliest response to paraquat The results of present study showed that paraquat is toxic to A. testudineus and any application towards aquatic environment must be handled with caution