Histology of carp (Cyprinus carpio, L.) gills and pond water quality in semiintensive production

Abstract

Gills of carp from ponds of the "Vrsacki ritovi" fish farm were studied, and the results discussed with reference to the results of physical and chemical properties of pond water. Subepithelial edema and gill hyperemia that are classified as mild and reparable were found the most frequently. High ammonia level that occurred periodically and increased pH values induced gill epithelial hyperplasia. Symptoms of environmental gill disease were observed in less than quarter of samples examined. Parasites invasion was recorded in all samples and could be related to the increased organic matter content. Although different gill changes were found, there were always parts of the gill apparatus still functionally normal and able to adapt to environmental changes that in this study, exceeded values recommended for carp production only temporarily.