Evaluation of Genotoxicity by Comet Assay in Tissues of Clarias gariepinus Exposed to Cassava Effluent

Abstract

Untreated wastewater discharge into waterbodies poses a number of risks, including the potential for aquatic organisms' DNA to be damaged. Using the comet assay, this study assessed the genotoxic impact of cassava wastewater on the gonads, liver, and gills of post-juvenile Clarias gariepinus. The post-juvenile C. gariepinus fish were acquired from a fish farm in Edo State, Nigeria, and were subjected to different concentrations of cassava wastewater (0.2%, 0.3%, 0.5%, and 0.7%) for a duration of 96 hours. In contrast to the typical actions seen in the control groups, the fish exposed to the effluent exhibited restless, erratic movements, and gasping for air. The first set of repetitions showed that catfish mortality increased with concentration; after 96 hours, exposure to the lowest concentration (0.2%) and the highest concentration (0.7%) of cassava wastewater caused 10% and 40% of the fish to die, respectively. The second set of repetitions showed that catfish mortality increased with increasing concentration; after 96 hours, exposure to the lowest concentration (0.2%) and the highest concentration (0.7%) of cassava wastewater resulted in 20% and 50% catfish mortality, respectively. Following the exposure time, the fish were brought to the lab where their gonads, liver, and gills were removed in order to use the comet assay for genotoxic assessment. The genotoxins present in the wastewater can be the reason for the DNA impairment found in the genotoxic assessment result at different effluent concentrations. The investigation also showed that DNA damage increased with increasing concentration, indicating a dose-dependent genotoxic effect of cassava wastewater on post-juveniles of C. gariepinus. This research demonstrates the critical importance of treating wastewater before to discharge.