Histological analysis of Bryconops caudomaculatusgills and liver under different concentrations of ammonia

Abstract

The objective was to evaluate the effects of different concentrations of ammonia (zero; 0.15; 0.30; 0.50; 1.00 mg L^-1 NH₃) on histology and morphology of gills and liver of juvenile Bryconops caudomaculatus. After 96 hours of exposure, the fish were anesthetized and necropsied for to collect gills and liver, which were embedded in paraffin. Morphological changes were observed on the secondary lamellae of the gills under concentrations greater than 0.15 mg L^-1, as hyperplasia, hypertrophy, epithelial displacement, lamellar fusion, swelling, lamellar aneurysm with rupture of the epithelium and increase in width of the lamellae. The liver presented histopathologies (congestion in the capillaries and inflammatory processes) at the presence of 0.30 mg L^-1 of NH₃, compromising the vital functions, the metabolism, breathing processes, detoxification of the body, hematopoiesis and probably hindered osmoregulation. The results suggest that the changes in gill and liver can be used to monitor fish performance in intensive farming.