Parasitism with Protozoa and Monogeneans in Fish from the Natural Waters of Romania

Parasitism by protozoa and monogenean flatworms in freshwater fish from Romania was studied by collecting and examining samples from two major river systems there: 183 fish from 17 species from the Olt River and its tributaries; and 155 fish from 16 species from the Mureș River and its tributary, Târnava Mare. The average rates of parasitism in the samples from the two rivers and their tributaries were as follows: (2%), spp. (21%), spp. (18%), spp. (8%), spp. (9%), and spp. (10%). The number of parasite species varied from one river to another. was found in only 3 fish species, spp. in 13 species, spp. in 6 species, and spp., spp., and spp. in 7 different species each. The highest number of parasite species (six) were identified in the European chub ( ) and schneider ( ), which seem more susceptible to parasitic infections. The aquatic environment of these rivers may represent a source of parasites for fish from neighboring countries through which these rivers pass.