Sublethal behavioral and biochemical toxicity of cypermethrin in juvenile Oreochromis niloticus in a static bioassay

Abstract

Sublethal behavioral and biochemical toxicity of cypermethrin in Oreochromis niloticus (L.) juveniles was accessed under static conditions at concentrations of 0.5, 1.1, and 2.1 µg L⁻¹ for up to eight weeks. The juveniles were highly sensitive to cypermethrin, with a 96-h LC₅₀ of 12 µg L⁻¹. Biphasic trends were noted for four avoidance behaviors: loss of equilibrium; erratic swimming; air gulping; opercular ventilation. Dose- and duration-dependent increases occurred in mucus secretion and color change. Mixed trends were noted for mean glutamate pyruvate transaminase, triglycerides, proteins, and cholesterol. These parameters decreased significantly depending on dose and duration in weeks two and six, but they increased in week eight. Mean glucose and glutamic oxaloacetic transaminase increased significantly depending on dose and duration up to week eight. No differences in glucose were noted in the control in week two. The findings of the present study confirmed that cypermethin adversely affected the health of fish even at a sublethal level.