Ultra-structural Alterations in Scales and Kidney of Common Carp after Exposure to Synthetic Pyrethoid Insecticide Deltamethrin

Deltamethrin (DLM), a type II synthetic pyrethroid is one of the most commonly used insecticide worldwide. It contaminates aquatic ecosystems via airborne dispersal, runoff, or groundwater percolation. This insecticide poses a significant threat to aquatic organisms, particularly fish. In the present study effects of synthetic pyrethroid DLM on common carp fish was studied by scanning electron microscopy (SEM) of scales and transmission electron microscopy (TEM) of kidney after treatment with different sub lethal concentrations for 28 days period. Sub lethal concentrations were selected on the basis of 96hrs LC50 value of pesticide. SEM analysis of changes in surface ultra-structure of scales of common carp revealed damaged lepidonts, circuli, radii and focus irregular and broken circuli and widening of interspace between circuli after treatment with different sub lethal concentrations of DLM. TEM study revealed that DLM exposure led to changes like fragmented endoplasmic reticulum, dilated and swollen mitochondria, nuclei with condensed chromatin, deformed nucleus, degenerated nuclear membrane and severe vacuolization in kidney of common carp. The concentration of the toxicant and the length of exposure were directly related to the degree of damage observed in the kidney and scales of the fish. Higher pesticide concentrations and longer exposure periods were consistently associated with more severe scale and kidney damage.