Research Product

A single case of adenocarcinoma of the retinal pigment epithelium occurred in a guppy, Poecilia reticulata Peters. This is the first such tumor reported from fishes. The left eye of the affected fish was severely exophthalmic because of a large intraocular tumor mass. The tumor, which displaced normal retina anteriorly, consisted mainly of melanin-containing epithelial cells. Neoplastic cells were bilayered and arranged in a tubular pattern. The tumor appeared to be confined to the orbit. Although the specimen was from a group exposed to a mixture of halogenated organic compounds, we do not consider the lesion to have been chemically induced because of its rare occurrence.