Study on oxygen requirement of striped catfish (Pangasianodon hypophthalmus) at different sizes and temperatures

Abstract

Striped catfish (Pangasianodon hypophthalmus), a facultative air-breathing fish is one of the high values species in aquaculture industry of Mekong delta, Vietnam. This study was performed to determine the basic oxygen requirements of Pangasianodon hypophthalmus at different sizes and temperatures in order to provide scientific bases for optimizing management practices of striped catfish ponds. Bimodal intermittent-closed respirometer was used for study. Two fish sizes (small: 6.7±0.3 g and large: 106±2.3 g) were chosen for this study. Thirteen small fish was divided for 3 levels of temperature 27±0.2ºC (n=3), 30±0.2ºC (n=5), 33±0.2ºC (n=5) and twelve large fish for 27±0.2ºC, 30±0.2ºC and 33±0.2ºC (n=4 at each temperature). Individual fish of every treatment was measured for oxygen consumption (MO2) from water (MO2w) and air (MO2a) for 20 hrs, then measurement of background respiration (by bacteria respiration) for 2 hrs. without fish. The results showed that the interaction between temperature and body size of fish had significant effect on air oxygen consumption and percentage of aerial oxygen uptake from air (p<0.05). RMR (routine metabolic rate) and SMR (standard metabolic rate) were not significantly different at 27ºC, 30ºC for 6.7 g and 106 g fish; but they were significantly different at 33oC for 6.7 g (357±28.5 mgO2kg-1h-1, 201±11.0 mgO2kg-1h-1) and 106 g (248±7.9 mgO2kg-1h-1, 196±11.2 mgO2kg-1h-1). Besides, the percentage of aerial oxygen uptake from air of 6.7 g had significant difference between 30 and 33ºC (p<0.05) with 29.1±4.5%, 47.9±3.8%, respectively; vice versa fish in group 106 g had no significant difference at 27, 30 and 33ºC. Oxygen consumption of fish was increased with the increased temperature reaching the highest level at 33ºC. This indicates that small fish needs more air oxygen consumption and large fish requires more oxygen in water for growth with a high temperature.