Hematological Profile of Juvenile European catfish (Silurus glanis) Reared under Different Stocking Densities in Recirculating System Conditions

The aim of present study was to evaluate the hematological parameters and the absolute number of leukocytes of European catfish (Silurus glanis) maintained in different technological conditions induced by applied stocking densities. The experiment was conducted over a period of 32 days. A number of 450 European catfish, with an average weight of 158.9±0.26 g, were distributed in four rearing units, in order to create different stocking densities as follows: V1-14.28 kg/m3, V2–28.59 kg/m3, V3–42.97 kg/m3 and V4-57.06 kg/m3. The following hematological parameters were determined: RBC, Ht, Hb, MCV, MCH and MCHC. A decrease of RBC and higher values of MCH and MCHC were observed at V4, while at V1 an increase in RBC and lower MCV, MCH values can be seen. Regarding the absolute number of leukocytes, no significant statistical differences were registered between the applied stocking densities (p>0.05). However, there was a slight increase of leukocyte number with increasing stocking density (240.01 x103cel./mm3 at V4, respectively 189.64 x103cel./mm3 at V1). It can be concluded from hematological parameters analysis that a stocking density of 60 kg/m3 seems to be out of the optimal range for catfish growth, in current growth conditions.