Vol. 4, Issue 3, Part C (2018)

Abstract
Octylphenol is an estrogenic environmental pollutant, widely used in the production of phenolic resins and octylphenol ethoxylates, which are used in the manufacturing of paints, textiles, detergents, pesticides and cleaning agents. The present study evaluates the median lethal concentration of octylphenol in the cichlid fish, Pseudetroplus maculatus for 96 h by probit analysis. Fish was exposed to eight different concentrations of octylphenol (50, 100, 150, 200, 250, 300, 350 and 400 μg/L) for 96 h along with control groups, maintaining ten animals in each group. Physico-chemical parameters of water as pH, hardness, dissolved oxygen and temperature were maintained during the treatment period. Mortality and behavioural changes of fish were observed and recorded throughout the experiment. The median lethal concentration (LC₅₀) for 96 h, determined by probit analysis was 150μg/L that killed 50% of the test animal. In all treatment groups, body weight remained unchanged whereas the mucous deposition was increased significantly in concentration-dependant manner when compared with the controls. Octylphenol treated fishes showed slow and restricted movement throughout the treatment period when compared to the control fishes. The entire body became haemorrhagic, fishes stayed in groups at the bottom with restricted activities and moved slowly towards the surface to gulp air, also showed inability to maintain normal posture and finally became lethargic. Octylphenol treatment altered the histo-architecture of gill and liver tissues which is evident by the degenerated primary and secondary lamellae or upliftment of epithelium of gill and vacuolated or necrotic hepatocytes at all concentrations. The results of the study concluded that octylphenol caused acute toxicity to fish when exposed for 96 h which is revealed by behavioural modifications and histological alterations that can be used as an indicator of ecologically relevant monitoring of environmental contaminants.