Mutagenicity testing of water with fish: a step forward to a reliable assay

A step forward has been set towards the realization of a reliable "sister-chromatid" exchange (SCE) assay with fish for the detection of mutagens in water. This test can detect mutagenic contaminants in water without prior concentration steps. A healthy breeding stock of the tropical fish Nothobranchius rachowi has been set up in our laboratory. This fish is particularly suited for the SCE assay because of its low number of chromosomes. The major improvement consisted of the development of a reliable staining technique for the differentiation of sister-chromatids. The assay can now be used for research purposes. With a few improvements it can become a rapid low-cost test for the screening of effluents on contamination with DNA-damaging agents.