STUDIES OF EUROPEAN CATFISH (SILURUS GLANIS L.) LEUKOCYTES REACTION IN THE CONDITION OF REARING IN ”FLOW-THROUGH” AQUACULTURE SYSTEMS

Researches in this paper have assessed the hematological response of European catfish to the crowding stress induced by high stocking density through the evaluation of WBC complex reactions, in order to determine the effect of the technological factors on the physiological status. The catfish exemplars belonging to the two experimental variants had individual weight of 619.74 ± 216.49 g / ex. for the first system VE 1, respectively 560, 83 ± 193.20 g / ex. for the VE 2. Through the experimental design we have created two stocking densities of 64 kg /mc, respectively 28 kg/mc. In order to achieve the purpose of the experiment the blood samples were immediately used to make smears which were colored with May-Grunewald Giemsa panoptic method. By studying different types of leucocytes was determined leukograma and absolute number of leukocytes (reported in 1000 erythrocytes counted on haemocytometer). We have identified the following types of white blood cells: lymphocytes, monocytes, neutrophils granulocytes and rarely, basophils. Eosinophils were absent. The total number of leukocytes, in general, has not been registered statistically significant changes. Lymphocytes (relative and absolute) have remained relatively constant, without significant variation. Stocking density has triggered a monocytosis phenomenon (significant increase in monocytes by 62 - 85%); neutrophils have been registered a slight reduction. In this experiment, stocking density did not affect the immune defense system of the Silurus glanis specie.