Our precise knowledge of the chaotic structure of aquatic ecosystems and the toxicological input parameters in the environment is rather uncertain. In this regard, computational toxicological models provide logical approaches to include solutions to uncertainty and variability problems and to report results. In addition, computational toxicological applications have an important potential to ensure environmental safety. However, the use of computational applied methods, as well as in vitro methods, is increasing day by day in order to predict the interactions of toxic substances and in vivo susceptibility analysis in toxicity studies. It is aimed to examine and compare the toxicants in similar tissues of two different fish species taken from a freshwater ecosystem seperately with a deterministic mathematical model, in this study. Depending on the mathematical calculation, a species- and metal-specific mathematical model was determined. As a result, it has been tried to present a case study about which mathematical approaches will be suitable for which biological studies, while showing that considering different mathematical modeling approaches can provide more reliable and informative results in biological studies.