SummaryHistopathological study of infections withCryptobia iubilansNohýnková 1984 in two species of freshwater aquarium cichlids (Herichthys cyanoguttatumandCichlasoma meeki) revealed severe tissue changes which were not limited to the digestive tract but also affected other principal body organs. The lesions were extensive enough to cause mortalitiesC. iubilansis thus far the only clearly pathogenic species among cryptobias infecting fis