HEALTH STATUS OF CHUB (Squalius cephalus) IN RELATION TO WATER QUALITY OF SAVA RIVER

Water quality has infuence on the health status of the organisms living in it. In the available literature, there is only a few reports on the health status of chub, particularly in the Sava river. The aim of this study was to estimate health status of chub as indicator of water quality. Furthermore we aimed at relating fish histology and parasitology to the number of bacteria in the water. We sampled 289 chubs for parasitological and histological examination. Fish were sampled on five sites from slovenian–croatian border through to the inflow of river Una in Sava. At the same time, water was sampled for the counting of coliforms and heterotrophic bacteria. The difference in the number of bacteria in the water was pronounced at different locations, with Oborovo and Otok Samoborski having the highest and the lowest values respectively. The intensity of histological parameters was in correlation with the number of bacteria in water. At least one histological parameter highly correlating with the water quality was found in every organ. Regarding parasite invasions, only ichthyophthiriasis and trichodiniasis showed high negative correlation with microbiological quality of the water. As part of parasitological examination, molecular methods were used for the identification of Acanthocephala