Toxicological evaluation of histoarchitectural alterations in various tissues of zebrafish (<i>Danio rerio</i>) exposed to three sub-lethal concentrations of atrazine

Environmental pollutants, primarily widely used herbicides such as atrazine, pose substantial risks to aquatic ecosystems. Atrazine is commonly detected in surface waters and has been shown to impair growth, physiological processes, and reproductive functions in aquatic organisms. The present study aimed to examine the sub-lethal toxicological effects of atrazine on Danio rerio (zebrafish), with particular attention to growth performance, enzymatic biomarkers, and organ-specific tissue damage. Juvenile zebrafish were exposed to atrazine at concentrations of 0.83, 1.25, and 2.5 ppm for 100 days. Growth parameters were measured, and biochemical assays were conducted to assess hepatic and cellular damage marker glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT) activity. Histopathological analyses of liver, gill, and gonadal tissues were performed to identify structural and functional impairments. Atrazine exposure resulted in a concentration-dependent reduction in body weight and total length, indicating impaired somatic development. Significant increases in GOT and GPT levels were detected, which suggest hepatocellular damage and increased tissue stress. Histological analyses identified severe pathological changes, including hepatocyte degeneration, gill lamellar fusion, and testicular atrophy. Distinct male- and female-specific responses further supported the dose-dependent nature of atrazine-induced toxicity. The findings demonstrate that chronic exposure to sub-lethal concentrations of atrazine induces significant physiological, biochemical, and histopathological disturbances in Danio rerio. These results highlight the detrimental impacts of atrazine on fish health and development and emphasize the need for strengthened regulatory controls and continuous monitoring of herbicide contamination in aquatic environments.