Basic morphological and hematological parameters were studied in adult, sexually mature individuals of Carrasius gibelio living in two rivers with varying degrees and different types of anthropogenic pollution (less disrupted site, domestic sewage pollution and heavy metal pollution) in Southern Bulgaria. The study was conducted on 30 female fish, age 3+ from each site. The results show that in C. gibelio, which inhabit the site with heavy metal pollution, the morphological parameters BW and FCF have the lowest statistically significant values. Specimens of C. gibelio from the river site with domestic sewage pollution have the following hematological profiles: erythrocytosis, leukocytosis and hyperchromia, differential leukocyte count: neutrophilia, eosinophilia, monocytosis and lymphocytopenia. Red cell indices (MCH, MCHC and MCV) display the highest statistically significant values. The C. gibelio specimens from the site with heavy metal pollution had the following hematological profiles: erythrocytosis, leukocytopenia and hypоchromia, differential leukocyte count: neutrophilia, eosinophilia, monocytosis and lymphocytopenia. The lowest statistically significant values of red cell indices (MCH, MCHC and MCV) indicate anemic changes of microcytic and hypochromic type. The hematological parameters of C. gibelio are adequate biomarkers of the physiological state of animals and their habitats.