Integrated Biomarker Responses Reveal Cypermethrin-Induced Stress and Organ Damage in Nile Tilapia: Insights into Hepatic, Neural, and Hematological Toxicity

Pesticides sprayed near waterbodies, without proper precautions, can cause detrimental effects on the fish population. Pesticides' polarity and water solubility determine the bioaccumulation of its in fish. A ten-day-long study was conducted to assess the toxico-physiological response in nile tilapia fish in four triplicated treatments, such as control (0 ppm) and three treatments following 25%, 50%, and 75% of \(\:{LC}_{50}\) of cypermethrin. The recommended dose for cypermethrin was 0.886 ppm, whereas the determined \(\:{LC}_{50}\)value is much lower, which is 0.668 ppm. The fish were sampled at the end of the experiments, and a substantial drop in RBC count was noted, corroborated by a reduction in hemoglobin levels after 7 days. On the other hand, elevated WBC count occurred as a reaction of the defense system. Similarly, ameliorated antioxidant levels were found to safeguard cells from oxidative stress. However, Total Antioxidant capacity (T-AOC) demonstrates a notable decline, which measures the overall ability of cells or tissues that neutralize free radicals and ROS. It represents the overall failure of the antioxidant defense system to counteract sustained oxidative pressure. Serum calcium levels exhibited a dose-dependent decline, indicating how calcium ions mediate cellular reactions under stress. Enzymes are reliable markers of the general health of fish. Cypermethrin exposure significantly elevated the activity of both plasma glutamic oxaloacetic transaminase and plasma glutamic pyruvic transaminase enzymes in Oreochromis niloticus after 7 days, presumably due to damage to muscle and hepatic tissues, as evidenced by histopathological observations of the liver cells. In addition, a notable rise in Aspartate aminotransferase, Alanine transaminase, and Alkaline phosphatase was identified, indicating metabolic disruptions. Histological studies of the intestine and liver aligned with the biochemical disruptions. The findings suggest that even sublethal doses can induce physiological alterations, underscoring the need for cautious pesticide application.