Acclimation conditions and subsequent acute hypoxia challenges do not affect the frequency of erythrocyte nuclear segmentation in triploid brook charr Salvelinus fontinalis (Mitchill 1814).

Routine observations of blood smears have repeatedly shown that triploid fish have a greater proportion of erythrocytes with nuclear segmentation (ENS) than diploids; however, there is as yet no understanding of why this is the case and whether it affects erythrocyte function. In an attempt to address this, we examined blood smears from two previous experiments to determine whether ENS frequency is affected by rearing conditions (acclimation temperature or dissolved oxygen level) and subsequent acute aerobic distress in diploid and triploid brook charr Salvelinus fontinalis (Mitchill 1814). As expected, triploids had a higher ENS frequency than corresponding diploids, but with no biologically significant effect of experimental conditions on ENS frequency in triploids. ENS was too rare to examine the effects of these conditions in diploids.