It is known that zeolite, tested in animal feeds in recent years, has a positive effect on fish growth and many physiological parameters. For this purpose, rainbow trout (Oncorhynchus mykiss) was fed with feeds containing zeolite at different rates (1%, 3%, and 5%) for three months in the present study. Fish growth parameters (live weight gain, specific growth rate, feed conversion rate, condition factor, and mortality rate) and hematological indices (total erythrocytes count (RBC), total leucocytes count (WBC), hemoglobin (Hb), hematocrit (Hct), total plate count (PLT), erythrocyte sedimentation rate (ESR), mean cell hemoglobin concentration (MCHC), mean cell hemoglobin (MCH), and mean cell volume (MCV) were examined monthly during the experiment.
At the end of the feeding period, the changes in growth parameters were determined, and only condition factor was found statistically significant (p <0.05). The highest condition factor calculated was 0.70 in group Z3 at the end of the study. In the hematological indexes, different ratios of zeolite added diets were found to cause a change in the blood indices, of which WBC, ESR and MCV values were statistically significant (p <0.05).