Effects of Pyrethroid Insecticides on Freshwater Fish: A Mini-Review

Abstract Synthetic pyrethroids are widely used because of their rapid biodegradability and non-persistent nature. However, these compounds frequently enter aquatic environments through agricultural run-off and spraying operations, where they adversely affect non-target organisms such as fish. This review summarises findings on the toxicological effects of pyrethroids on freshwater fish, highlighting physiological, biochemical, and histopathological impacts. Evidence shows that pyrethroids act as functional toxins that induce hyperexcitation or direct cytotoxicity, with fish exhibiting high sensitivity due to slow metabolism and elimination. Sublethal exposures reduce growth, alter water quality, impair behavioural responses, decrease glycogen reserves, and damage vital organs. These findings emphasise the need for improved insecticide management to reduce risks to aquatic life, especially fish.