Fish anaesthesia is commonly used to minimize stress and physical injuries during harvesting, transportation, and to alleviate stress during surgical operations. Due to the general depression of anaesthesia on cardiovascular and respiratory functions it causes significant changes in blood gases and pH. The aim of this study was to evaluate the disturbance caused by the three common fish anaesthetics (Benzocaine, MS-222, and Aqui-S) on blood gases and haematological parameters of commercial sized (approximately 1kg) stripped catfish (Pangasianodon hypothalamus). Blood samples were measured immediately after catheterization of the dorsal aorta of the anaesthetised fish, and subsequently at 3, 6, 24, 48, and 72 h of recovery in aerated water. All three anaesthetics caused immediate and severe reductions in plasma and red cell pH, followed by a progressive return to baseline values within 24 h. This initial disturbance was mirrored in increased lactate concentration and an elevated PCO₂, pointing to a mixture of a respiratory and metabolic acidosis. The anaesthetics also caused a marked rise in hematocrit, which seemed to be exclusively due to increased red blood cell counts, followed by a gradual normalisation within 24 h afterexposure. Similarly, there was a gradual decrease of glucose, cortisol, and hemoglobin concentrations. This study showed the similar efficacy of the three anaesthetics and that blood parameters are normalized within 24 h.