Acetylcholinesterase, glutathione and hepatosomatic index as potential biomarkers of sewage pollution and depuration in fish

•AChE GSH and HIS in fish are potential biomarkers for sewage water pollution monitoring.•Fish reared in treated sewage show high content of GSH and HIS and lower AChE than farm fish.•AChE inhibitory neurotoxic chemicals, heavy metals and industrial chemicals in STP effluent.•Restoration of biomarkers in depuration of sewage water fish were monitored.•Depuration was found to be an effective technique for detoxification of fish. The current study was designed to validate the biomarkers of sewage pollution in Mozambique Tilapia (Tilapia mossambica, Peters) reared in sewage treatment plant (STP) effluent in Ras Al Khaimah, United Arab Emerates, before and following depuration/detoxification. Cellular biomarkers, cholinesterase activity using acetylcholine as a substrate (acetylcholinesterase AChE) and reduced glutathione (GSH) and hepatosomatic index (HSI) were investigated in fresh water fish, Tilapia, raised in a fish farm (Group I/Clean, as Control), treated sewage water/TSW (Group II/Sewage) and thereafter exposed to fresh water in an aquarium for 6weeks (Group III/Depurated) for depuration. The results showed significantly lower levels of AChE activities in liver (26% p