Behavioral Responses of African Freshwater Fish Clarias gariepinus to Different Concentrations of a Commercial Herbicide, ‘Orizoplus’ (Propanil/2,4-D)

Abstract

The study was conducted to assess the behavioural responses of freshwater fish Clarias gariepinus subjected to different concentrations of  a commercial herbicide, ?Orizoplus (Propanil/2,4-D).The juveniles (20.3 ± 23.6g ) were purchased from local sources and acclimatized for two weeks under laboratory conditions. During the acute toxicity bioassay, behavioural responses of fish such as convulsions, fin movement, hyperactivity, somersaulting activity and erratic swimming rate were observed in exposed groups whereas the control group maintained a normal behaviour. The physicochemical properties measured in the test solutions showed that water temperature varied slightly while PH was constant. Dissolved oxygen, conductivity and total dissolved solids showed some variations ranging  from 2,78 ±6.08 mg/l, 49.2±59.6 µmhos, and 24.3 ±26.5 respectively. The fish in the highest concentration 140mg/l showed 100% mortality while the fish in the lower concentrations of 80mg/l and 60mg/l showed 0% mortality indicating that stress and eventual death of the fish is concentration dependent.

Keywords: Clarias gariepinus, Herbicide, Behavioral responses,Toxicity.