Hematological Parameters of Five Species of Marine Fishes

1. Blood oxygen capacity (BOC). hemoglobin (Hb) content, hematocrit (Hct). red blood cell (RBC) count, and pH were measured in five species of marine fishes which varied in activity from sedentary to fast swimming. 2. BOC and Hb content were correlated with the level of activity for a species. RBC and Hct varied between species and were more weakly correlated with levels of activity. Blood pH did not vary between the species studied. 3. These data suggest that increased BOC is correlated with high levels of activity in fish and that this increase is due to elevated Hb content of the blood. The increased Hb is generally accompanied by an increase in RBC count, so that the average corpuscular hemoglobin (ACH) remains the same