author(s)
Parvaiz Ahmad Ganie, Dar Jaffer Yousuf, Raja Aadil Hussain Bhat, Irfan Ahmad Bhat, Kishor Kunal, PK Pandey and Debajit Sarma

abstract
Environmental protection has fascinated the attention of the varied section of people globally thereby creating global issue amongst researchers and scientists working in this area. Pesticides are toxic to aquatic biota which form important components of the food chain such as fishes. Fishes are important sources of protein in nation-state’s diet. So a detailed understanding of the pollutant effect on fishes would be rewarding for fish conservation and fishery development. Cypermethrin, a synthetic pyrethroid pesticide and potential toxic pollutant contaminating aquatic ecosystems, was investigated in the present study for acute toxicity. Indian major carp (Cirrhinus mrigala) were selected for the bioassay experiments. Experimental fish were subjected to different concentrations of cypermethrin ranging from 0.40 to 6.40µg/l for 96 hrs in test containers. The static renewal test method of acute toxicity test was used. Water temperature was regulated at 26.8 ± 3° C. In addition, behavioral changes such as loss of schooling behaviour, swimming near the water surface, hyper activity, erratic movements, seizures, loss of buoyancy, darting movements and hitting against the walls of test tanks at each cypermethrin concentration were observed for the individual fish. Data acquired from the cypermethrin acute toxicity tests were evaluated using the arithmetic method of Karber. The 96 hr LC50 value for Cirrhinus mrigala was estimated as 4.57µg/l. The possible variation in the LC 50 values can be attributed to toxicant sensitivity, its concentration and duration of exposure.