HEMATOLOGICAL PARAMETERS IN THE RAINBOW-TROUT, ONCORHYNCHUS-MYKISS, IN CAGE CULTURE

The dynamics of the red blood cell count (RBC), haemoglobin (Hb), haem atocrit (PCV), mean cell volume (MCV), mean cell haemoglobin (MCH) and mean cell haemoglobin concentration (MCHC) were checked in 77 (1+) ra inbow trout, Oncorhynchus mykiss (Richardson), of the Kamloops strain (18 months old) at an average total body length of 240 mm and weight o f 230 g in fortnightly intervals during the period from June to Septem ber, All the parameters, except for the MCV, showed significant peaks during the first ten-day period of August; this was in correlation wit h the increase in water temperature (22 degrees C), dissolved oxygen c ontent (9.9 mg/l), oxygen saturation (112%) and BOD5 (4.4 mg/l). The d ependences of Hb and MCH on oxygen saturation (I-yx = 0.755 and I-yx = 0.770) and of MCH and MCHC on the oxygen content (I-yx = 0.870 and I- yx = 0.869) were found to have a parabolic pattern. The physiological values of the red blood cells of the rainbow trout reared in floating net cages at temperatures between 17 and 23.5 degrees C were as follow s (mean +/- s.d.): RBC 1.08 +/- 0.138 T/l, PCV 0.445 +/- 0.0473 l/l, H b 82 +/- 11.6 g/l, MCV 413 +/- 41.3 fl, MCH 76 +/- 9.2 pg and MCHC 0.1 8 l/l.