Leukocyte profiles of diploid and triploid tench, Tinca tinca L.

Leukocyte profiles were compared in diploid and triploid tench of the same origin. A total of 55 3-year-old (34 diploid and 17 triploid) and 61 4-year -old (28 diploid and 33 triploid) tench were examined in June of 1996 and 1 997, respectively. There were no significant differences in total or differ ential leukocyte counts between diploid and triploid 3-year-old tench, in w hich lymphocytes dominated (> 90%) the total leukocyte count. In the case o f 4-year-old tench, there were no significant differences in total leukocyt e counts, or in differential lymphocyte, monocyte and myelocyte counts, but triploids had lower metamyelocyte counts and higher neutrophile granulocyt e counts (P < 0.01). Lymphocyte frequencies in 4-year-old tench were only a bout 50%, and high counts of granulocytes and their developmental forms wer e registered. The differences observed between 3- and 4-year-old tench may have been due to worsening fish condition, brought on by previous stress an d/or local bacterial skin infection at the time of sampling the older fish. (C) 2001 Elsevier Science B.V. All rights reserved.