Weatherfish (Misgurnus fossilis) as a new species for toxicity testing?

Selection of appropriate test species is a critical issue when assessing effects of environmental contamination on fish because the ecological relevance of commonly used test species might be restricted due to their exotic origin. In the present study, a European freshwater fish with frequent occurrence in agricultural areas is suggested as a potential alternative: the European weatherfish (Misgurnus fossilis). Its suitability for acute embryo toxicity tests (FET) was investigated with regard to practical implementation, sensitivity to contaminants and tolerance against environmental conditions of concern. For this purpose, weatherfish embryos were exposed (72h) to the reference substance 3,4-dichloroaniline (DCA) in three independent tests. Furthermore, the effects of dissolved oxygen (DO) deficiency on weatherfish embryos were studied to evaluate their suitability e.g. for sediment bioassays. Obtained results revealed that the sensitivity of weatherfish embryos towards DCA (72 h-EC₅₀=0.52mg/l; 72 h-LC₅₀=0.71mg/l) was highest compared to other species and three times higher than that reported for the commonly used zebrafish (Danio rerio). Even though knowledge of DO requirements during the embryonic period of European fish species is scarce, weatherfish can be stated as one of the most tolerant native species (LC₉₀ for DO=0.53mg/l after 48h exposure plus 72h post-exposure). Its high ecological relevance for Europe, the particular sensitivity towards DCA and high tolerance against DO depletion highlight the potential of weatherfish as additional species for toxicity testing.