Nodular and epicellular coccidiosis in the intestine of cyprinid fishes

Abstract

In the intestine of 10 cyprinid fish species collected from natural waters of Hungary, the author demonstrated oocysts which were shed unsporulated. In 6 of the fish species, oocysts of 2 sizes were observed. Histological examinations proved that, of the morphologically similar oocysts, larger ones developed in nodules in size of a pinhead in certain segments of the gut. Smaller oocysts were formed in the epicellular layer of epithelial cells and were distributed evenly in the intestine. Both nodular and epicellular type coccidioses are characterized by a 1-yr developmental cycle. Infection is demonstrable only in the spring. Merogonic stages were found in March and gamogonic stages in April. By May, the infection practically disappeared. Oocysts collected from different fish species varied slightly in morphology. Therefore, without knowing host specificity, only the nodular and epicellular coccidia found in the most infected fish species, Blicca bjoerkna , are described as new species, Goussia balatonica and G. pannonica .