The Influence of Selenium and Mercury Ratios on Body Characteristics in Common Carp

The aim of this study was to quantify the levels of selenium and mercury in the blood serum of common carp (Cyprinus carpio) and to investigate their interrelationship and potential influence on fish physical parameters. This study expected that the calculation of the molar ratio of these elements would reveal possible correlations with the total length (TL) and weight (W) of the fish. The quantification of selenium and mercury was quantified using the ICP-OES method and the physical parameters of the fish were measured in situ at the time of sampling by a specialized expert. Selenium, an essential bioactive element, contrasts with mercury, a non-essential toxic element, due to their antagonistic interactions in biological systems. Selenium has the ability to mitigate the toxicity of mercury by forming non-toxic complexes, such as the tetraselendimercuric compound (HgSe), also known as tiemannite. Previous studies have suggested that a Se:Hg molar ratio greater than 1 is associated with the protective effects of selenium against mercury toxicity. In this study, selenium was detected in only a subset of samples, while mercury was found in all samples analyzed. Statistical analyses, including correlation analysis and linear regression, were performed using GraphPad Prism 8.1. However, no statistically significant correlations were found between the molar ratio of selenium and mercury and the physical parameters of the fish. This result can probably be attributed to the limited sample size and the smaller number of samples in which selenium levels could be quantified.