Studies on acute toxicity of synthetic pyrethroid λ-cyhalothrin on freshwater fish labeo rohita

Abstract

Aim : To study the acute toxicity of λ-cyhalothrin in freshwater fish Labeo rohita by determining the 96 hours lethal concentration 50 (96 hrs LC50 ) and behavioural patterns of exposed fish. 50 Materials and Methods: Atotal 270 fingerling size fish were used to determine the 96 hours lethal concentration 50 (96 hrs LC50 ) of λ-cyhalothrin as per the guideline of Organization for Economic Co-operation and Development (OECD) 203 except 50 the loading density which was higher than the recommended density 1.0 g/l to reduce the chemical loss. The fingerlings were brought from the local fish hatchery, disinfected and acclimatized for 14 days in laboratory conditions. 60 fingerlings, 10 each were divided into six plastic tubs of 35 L capacity with 0 ug/L (control), 10 ug/L ethanol only (vehicle control), 0.1 ug/L, ug/L, 5 ug/L and 10 ug/L of λ-cyhalothrin in 20Lof dechlorinated tap water. Static renewable bioassay was conducted using ive selected doses in between concentrations causing 10 to 100% mortality i.e. 2 ug/L, 2.5 ug/L, 3 ug/L, 3.5 ug/L and 4 ug/L long with control and 4.0 ug/L of acetone only as vehicle control. Water quality parameters like temperature, pH, total ardness and total alkalinity were measured daily. The experiment was repeated three times. Behavioural pattern and mortality as recorded periodically. esults: The fish exposed to chemical showed erratic swimming, loss of balance, surfacing and convulsions in a dose ependent manner. 2.72 ug/Lwas calculated as 96 hrs LC50 value for λ-cyhalothrin in Labeo rohita. conclusions: λ-cyhalothrin was reported as highly toxic chemical for Labeo rohita producing altered behavioural pattern inose dependent manner. © The authors.