Micronucleus occurrence in diploid and triploid rainbow trout (Oncorhynchus mykiss Walbaum)

The aim of the study was to observe the influence of different ploidy levels in fish on micronucleus occurrence. Twenty minutes after fertilization, one group of rainbow trout eggs was exposed to water temperatures of 26degreesC in duration of 20 minutes to induce triploidy. Second group was kept in water temperature of 10degreesC, which is optimal for development of rainbow trout. The frequency of micronucleated erythrocytes was determined in the peripheral circulation of rainbow trout 67 days (following absorption of the yolk - swim-up stage) and 128 days (fry stage) post fertilization. There was a significant difference (P < 0.001) between frequency of micronucleated erythrocytes of diploid (1.10 +/- 0.96parts per thousand) and triploid (2.41 +/- 1.28parts per thousand) fish at swim-up stage. Increased mean values of micronucleus in diploid (1.80 +/- 1.57parts per thousand) and triploid (5.92 +/- 3.80parts per thousand) fry were also recorded.