Toxicological Impact of Cypermethrin in Common Carp (Cyprinus carpio): A Study on Behavior, Morphology and Gills

Introduction: Aquatic ecosystems are increasingly vulnerable to contamination from the agrochemicals, a consequence of expanding agricultural practices and the intensification of pest control measures. Aim: To investigate the toxic impact of cypermethrin (CYP) in common carp (Cyprinus carpio) by assessing behavioral responses, morphological alterations and histopathological alterations in gills for 15 and 45 days. Study Design: This was an experimental laboratory based toxicological study conducted in the Department of Zoology, Maharaja Agrasen University. The research study was carried out over a distinct duration. During the entire experimentation, controlled laboratory conditions were maintained for performing the exposure experiments, monitoring responses and evaluating the toxicological impact. Material and Methods: Healthy Cyprinus carpio (n=15, average weight/length 12 ± 2 g/11 ± 2 cm) were acclimatized in the laboratory conditions and divided into control and exposed groups. Fish in exposed groups were administered sublethal concentration 0.41 µg/L cypermethrin for 15 and 45 days. Behavioral alterations were recorded daily and morphological changes were photographed. Gill tissues were fixed in buffered formalin and processed for histopathology using H&E staining. The statistical analysis was performed to compare results between control and exposed groups by using one way ANOVA test. Results and Discussion: Cypermethrin-exposure for 45 days exhibited pronounced behavioral abnormalities, such as hyperactivity, erratic swimming, excessive dorsal fin movement, frequent air gulping, and increased opercular activity as compared to 15 days exposure. Marked morphological changes were observed in 45 days group like discoloration of body color, scale erosion, caudal fin bruising and red blotches on the snout. Prolonged exposure for 45 days revealed prominent histopathological changes such as curling of secondary lamellae, epithelial lifting, lamellar fusion, hyperplasia, aneurysm formation, necrosis in the gill tissue. While, a very few behavioral, morphological and histopathological alterations were observed in fish exposed to cypermethrin (CYP) for 15 days. Conclusion: Cypermethrin exposure induces severe behavioral, morphological and histopathological alterations in Cyprinus carpio over prolonged exposure. These findings highlight the ecological risks of cypermethrin contamination in aquatic environments and underscore the need for its regulated use to safeguard aquatic biodiversity.