A dinoflagellate parasite from tropical fish

In stocks of siluriform and cichlid ornamental fishes imparted from differe nt locations in tropical Africa and South America. infections with vegetati ve cysts of a dinoflagellate occurred on skin, fins and gills. In affected fish the skin was covered with a greyish mucus layer and white spots develo ped like in infections with Ichthyophthirius multifiliis. The fish stopped feeding and in some stocks up the 100% of infected Fish died within 7 to 14 days. Treatments with standard procedures against ectoparasites were not s uccessful. The dinoflagellates were identified based on the presence of a d inokaryotic nucleus with condensed chromosomes. On fish vegetative cysts bu t no trophonts were found. The cysts induced an epithelial cell hyperplasia . The epithelium cells formed a thickend layer which enclosed individual cy sts or aggregates of cysts.