Occurrence of parasites in Cobitidae from Croatian rivers draining into two different watersheds

Members of the Cobitidae family are not economically important, thus few studies have been made on their pathology. A survey of parasitic fauna of some representatives of the loaches, such as Cobitis elongata , C. elongatioides, and the recently described C. bilineata, was carried out during the spring and summer of 2006. Fish samples were collected from four Croatian rivers: the Sava, Drava and Kupa draining into the Danubian system, and the Zrmanja draining into the Adriatic system. Specimens were of varying size, weight and age. Ectoparasitological examination revealed infections by the ciliate parasites Trichodina nigra (61; 29%), Epistylis sp. (12; 9%), Chilodonella cyprinid (22; 58%), Ichthyophthyrius multifiliis (81; 81%), dinoflagellate Piscioodinium pillulare (6; 45%) and monogenean Gyrodactylus cobitis (22; 22%). Histopathological examination of haematoxylin-eosin stained tissues showed the presence of Sarcocystis sp. in the muscle of one specimen. Dissections revealed an isolated finding of plerocercoid of Ligula colymbi in a Drava river specimen. A more comprehensive survey is necessary to determine the actual threat of the parasitoses to endangered species of the Cobitidae family.