show Abstracthide AbstractThe Amazon Molly, Poecilia formosa, was first introduced to biomedical research in 1979 when it was listed in the "Registry of Animal Models for Human Disease" for DNA damage studies. Since then it has been used for carcinogenicity studies with physical and chemical agents, as test organism in ecotoxicology, for research on infectious diseases, and for experimental cancer research. This fish stands out from all other aquatic models by the unique feature of genetic clonality. This is due to its unusual mode of reproduction. Females produce diploid eggs without meiosis, which are then triggered for parthenogenetic development by sperm of males from related species. There is, however, no paternal genetic contribution and all offspring develop as clones of their maternal lineage. The proven true clonality thus allows researchers to perform experiments with animals that are genetically identical. This guarantees the utmost reproducibility of independent studies, a stereotype development of diseases or physiological processes under scrutiny and a highly comparable biological material.