This study examined the hematological profiles and responses to exhaustive exercise in 'all-fish' growth hormone (GH) transgenic common carp (Cyprinus carpio L.) compared to non-transgenic controls. Transgenic fish had significantly smaller erythrocytes (length, width, surface area and volume), with a larger surface to volume ratios than non-transgenics. There were no significant differences in hematocrit, blood hemoglobin concentrations, plasma glucose, lactate, cholesterol and protein concentrations between the two strains at rest, but the tr...