Lesser known aquarium fish tumor models.

The repeated use of particular species for experimental oncology in fish increases their future value by accumulating background information for these models and justifies the establishment of genetic stock centers. However, the wide diversity that exists within the class Osteichthyes and Chondrichthyes suggests that the ideal surrogate models for studying some types of neoplasms might be found among lesser known species. To help assess cultured fish as surrogates for some other types of human neoplasia, we examined cases in the archives of the Registry of Tumors in Lower Animals and reviewed reports in the literature. Spontaneous and induced neoplasms originating from a spectrum of cell types were seen in more than 215 fish species commonly raised in aquaria or cultured for study among 69 families. Prominent families include the Poeciliidae (livebearers), Cyprinidae (carps and minnows), Cichlidae (cichlids), Cyprinodontidae (killifish), Characidae (tetras), Adrianichthyidae (medakas), Aplocheilidae (rivulins), and Salmonidae (salmon and trout). The following are examples of potential fish tumor models that have received less consideration than some others: papilloma and carcinoma of the urinary bladder in oscar (Astronotus ocellatus); osteogenic neoplasms, peripheral nerve sheath tumors, and ependymoblastoma in coho salmon fingerlings (Oncorhynchus kisutch); and nephroblastoma resembling Wilms' tumor in Japanese eels (Anguilla japonica).