Impact of chlorpyrifos toxicity on gill damage of two species of freshwater fish in Lake Diatas

Background: Lake Diatas is one of the important lake which is influenced by agricultural activities around the lake, and chlorpyrifos is widely used as a pesticide in this area. This study aimed to analyze the damage of the gill tissue of Oreochromis niloticus L. and Cyprinus carpio L. as two freshwater fish, which are mostly caught to be consumed by the residents in Lake Diatas, Indonesia, that were exposed to chlorpyrifos. Methods: Acclimatization was performed for 14 days and continued with toxicity test for 30 days. Chlorpyrifos exposure was tested at various concentrations. Fish gill tissue was observed microscopically in 10, 20, and 30 days of exposure, and damages were scored based on the level of gill tissue damage. Results: It was revealed that O. niloticus L. experienced edema, proximal basal hyperplasia, fusion, hyperplasia in all secondary lamellae, and necrosis at the higher exposure concentration. While C. carpio L. experienced fusion, hyperplasia, clubbing, necrosis, and obvious degradation of gill tissue of fish after 30 days of exposure to chlorpyrifos. There was a significant difference in the damage of fish gill tissue between each variation treatment (P < 0.05). Conclusion: According to the results, the higher the concentration of chlorpyrifos and the longer the exposure time, the higher the level of damage in gill tissue.