Heavy Metal Accumulation in Freshwater Fish: The Role of Species, Age, Gender, and Parasites.

The present study investigates the distribution of cadmium, chromium, and mercury levels in sediments, plants, and fish from Zemplínska Šírava, a historically contaminated reservoir in Slovakia. Using fish as bioindicators, we analyzed the impact of factors such as age, gender, ecological group, and parasite burden on heavy metal accumulation. Results revealed that mercury was highest in fish muscle, particularly predatory species, whereas chromium and cadmium were predominantly found in liver tissues. Chromium accumulation was influenced by gender, with females showing higher levels. Older fish exhibit greater cadmium accumulation in liver tissue. Parasite burden was associated with elevated mercury levels in fish muscle. Notably, the cestode Caryophyllaeus laticeps had significantly higher chromium levels than its host, freshwater bream (Abramis brama). This study highlights the important role of fish and parasites in monitoring aquatic contamination and illustrates the complex interplay of biological and environmental factors in heavy metal bioaccumulation.