Sublethal toxicity of commercial formulations of deltamethrin and permethrin on selected biochemical constituents and enzyme activities in liver and muscle tissues of Anabas testudineus

• Toxicity of type I pyrethroid permethrin and type II deltamethrin was studied.
• Both the pesticides significantly reduced glycogen in liver and protein in muscle.
• Deltamethrin was more toxic than permethrin to liver SDH and muscle lactic acid.
• Deltamethrin was toxic to fish at concentrations environmentally relevant in India.
• Liver was the most promising tissue for SDH, and muscle for AST and ALT assay.

The freshwater fish Anabas testudineus was exposed for 21 days to two commercial formulations of synthetic pyrethroids deltamethrin and permethrin at sublethal concentrations of 0.007 and 0.0007 mg L−1, and 0.093 and 0.0093 mg L−1, that represented 10% and 1%, respectively, of the 96 h LC50 of these two pesticides for this fish. The glycogen, protein and lactic acid contents, along with succinate dehydrogenase (SDH), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) enzyme activities in liver and muscle tissues of control and pesticide-exposed fish were estimated. When compared with those of control fish, significant depletion of glycogen content was observed in liver, and that of protein in muscle tissue of fish treated with both the pesticides at their higher as well as lower concentrations. Lactic acid reduction was significant only in fish muscle treated with deltamethrin. SDH level was reduced significantly in both liver and muscle tissues except in fish exposed to 0.0093 mg L−1 permethrin. AST level was reduced significantly in liver and muscle tissues and ALT in muscle tissue of deltamethrin treated fish only. It is concluded that deltamethrin, a type-II pyrethroid, is more toxic to fish than the type-I pyrethroid permethrin and is capable of rendering toxicity at a dose as low as 1% of its LC50 value.

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