Propagation in cell culture of the dinoflagellate amyloodinium, an ectoparasite of marine fishes.

Amyloodinium ocellatum, a common dinoflagellate ectoparasite of marine fishes, was successfully propagated on a fish gill cell line. In vitro infections were similar in cytopathology and development to those reported on natural hosts, and large numbers of parasites could be produced. Exposure of parasites in cell culture to an antiprotozoal drug produced a dose-dependent inhibition of infectivity that was much more sensitive than a motility assay previously used to assess the toxic effects of a drug on protozoan ectoparasites. This propagation system may be a useful model for studying the biology and control of protozoan skin parasites of fishes and for quantitatively studying hostparasite interaction at cellular interfaces.