Hematological Parameters in Trout: A Comparative Study between Rainbow Trout Oncorhynchus Mykiss (Walbaum, 1792) and Brown Trout Salmo Trutta Macrostigma (Dumeril, 1858)

The aim of this study was to obtain a basic knowledge of some blood haematological parameters in two different species of trout, Rainbow trout Oncorhynchus mykiss (Walbaum, 1792) and Brown trout Salmo trutta macrostigma (Dumeril, 1858). O. mykiss was caugh t in a farming system (commercial farm Palazzolo Acreide (Siracusa, Italy) while S. t. macrostigma in natural habitat (Anapo river, Siracusa, Italy). White Blood Cell Count (WBC), Red Blood Cell Count (RBC), Haematocrit (Hct), Hemoglobin concentration (Hg b), Mean Corpuscular Volume (MCV), Mean Corpuscular Haemoglobin (MCH), Mean Corpuscular Haemoglobin Concentration (MCHC), Thrombocyte Count (TC), were measured in blood samples from a total of 40 fish (20 for each species). The fork length, total weight a nd condition factor of the individuals were measured. Unpaired Student's t - test between two species showed statistically significant differences (P < 0.001) for RBC, Hct, MCV, MCH, MCHC and TC. No statistically significant differences were found in WBC and Hgb. These results are useful to obtain a basic knowledge of two different species of trout in order to monitor the health status of these species of great commercial value.