Quality of water from fish farms and histopathological analysis of tilapia ( Oreochromis sp.) in São José de Ribamar and Paço do Lumiar, state of Maranhão, Brazil

Abstract

The present work aimed to use histopathological gill biomarkers in tilapia (Oreochromis sp.) and physicochemical and microbiological analyses of water in the evaluation of impacts to fish farms located in São José de Ribamar and Paço do Lumiar, state of Maranhão, northeastern Brazil. Histopathological analyses performed on gills indicated morphological alterations in all tissues analysed. The lesions found were as follows: epithelial lifting, lamellar epithelium hyperplasia, blood vessel congestion, lamellar fusion, blood sinus dilation and lamellar aneurysm. Temperature, D.O., salinity and nitrite values obtained were considered within recommended standards. The pH verified in a pisciculture located in Paço do Lumiar is considered potentially stressful to fish and, therefore, predisposing to pathologies. Ammonia in a fish farm in São José de Ribamar is considered sublethal. In all fish farms evaluated, the presence of high counts of total coliforms for fish farms of São José de Ribamar was verified. Escherichia coli was verified in a cultivation in São José de Ribamar indicating faecal contamination of the nursery water by the flow of some source of domestic effluent. The integration of studies with physical, chemical and biological variables generates important data to evaluate the quality of fish production.