The effect of training on the lateral musculature of O-group roach, Rutilus rutilus (L.), and their fatigue in subsequent exercise tests



First year roach from a Stillwater habitat were maintained in an’artificial stream for periods of up to 40 days and samples of the lateral musculature were subjected to histological examination. It was found that there was a highly significant increase in the percentage of red muscle present in the hindermost regions of the fish confined for 30 days or more in the stream. In subsequent exercise tests, it was shown that the FV50 was higher for fish conditioned for 40 days, but it was considered unlikely that this increase in swimming ability was as a direct result of changes in muscle composition.