Haematological effects of prolonged sublethal hypoxia on channel catfish*<i>Ictalurus punctatus</i> (Rafinesque)

Abstract

Sub‐adult channel catfish, Ictalurus punctatus , were exposed to sublethal hypoxia for 24, 48 or 72 h. Haematological parameters were used to assess the physiological state of the catfish subjected to prolonged, sublethal hypoxia. Haemoglobin, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentreation, plasma lactic acid and plasma glucose deviated significantly from control values in channel catfish exposed to hypoxia for 24, 48 or 72 h. Haematocrit, total plasma protein, total erythrocyte counts, total leukocyte counts mean corpuscular volume and differential leukocyte counts were not sensitive indicators to the catfish's physiological status. After five days, of reacclimation to oxygen levels saturation, channel catfish continued to exhibit haematological responses to prolonged hypoxia.