Lake Edku pollutants induced biochemical and histopathological alterations in muscle tissues of Nile Tilapia (Oreochromis niloticus)

Abstract

This study aimed to assess some water quality parameters of Lake Edku, evaluation of the effect of a complex mixture of contaminants on the fish biochemical composition, and the histopathological changes in muscle tissue of Nile Tilapia, Oreochromis niloticus inhabiting different locations of Lake Edku. Methods: Water samples and 200 fish of O. niloticus were collected from different regions of Lake Edku and transported to the laboratory. Fish were divided into three groups: El-Maadyah region, Edku drain, and the recovery (El-Maadyah region). Recovery fish were left in aquaria for a month. Water quality parameters including temperature, pH, dissolved oxygen, electrical conductivity, total dissolved solids, and salinity were measured. Muscle total protein, total lipid, energy value, moisture, and ash content were determined, and the histopathology of fish muscle was examined. A significant decrease of dissolved oxygen in the Edku drain region compared to El-Maadyah and the recovery groups was observed. The salinity value showed a significant increase in the El-Maadyah region compared to the other groups. On the other hand, Edku drain fish group exhibited a significant decrease in muscle total protein, energy value, and ash content compared to the other groups. In contrast, it exhibited an increase in the water content and a significant increase in total lipids compared to the other groups. The muscle sections of El-Maadyah and Edku drain fish revealed several alterations compared to the recovery fish including hyalinized and necrotic muscle fibers, vacuolar degeneration, parasitic granuloma, infiltration of macrophages, dispersed muscle fibers by edema, fatty tissue, a variable amount of connective tissue proliferation between bundles and glycogen granules. The results confirm that fish contaminated environment could result in the damage of muscle tissue and has negative impacts on the fish quality and its validation to human consumption.