Biochemical and histological alterations in Aequidens metae (Pisces, Cichlidae) and Astyanax gr. bimaculatus (Pisces, Characidae) as indicators of river pollution.

The water quality from rivers near to cities has decreased drastically over the decades due to the environmental pollution. The Ocoa River on its way through the Villavicencio city, Colombia, receives large volumes of domestic and industrial wastewater. In order to establish the effect of the contamination, biochemical and histopathology biomarkers were evaluated in the gills and the liver of two native fish species. Astyanax gr. bimaculatus and Aequidens metae were caught in three sites of the Ocoa River (S1, S2 and S3) and in a reference River during the rainy and dry season. A. metae showed to be more sensitive to water pollution. In general, the rainy season induced a greater negative impact in the fish monitored. At site S3 (after crossing the city where urban runoff and industrial effluents are discharge and close to a landfill), increased inhibition of the antioxidant response and lipid membranes damage were observed; in addition, in this site the histopathological alterations were greater in both fish species. The impact observed in this study on fish health provoked for the Ocoa River contamination demands the need to begin strategies to solve the problem of discharge of domestic and industrial wastewater in aquatic environments in Colombia.