Air exposure test in Colossoma macropomum juveniles maintained in water at suboptimal temperature: Physiological, metabolic and oxidative stress responses

This study evaluated the physiological, metabolic and oxidative responses of Colossoma macropomum subjected to air exposure when maintained in water at suboptimal temperature (23°C). A total of 54 fish (81.33 ± 11.90 g) were distributed into nine tanks (6 fish per tank). For the air exposure test, 24 animals were exposed for 30 min and another 24 animals for 60 min. Six fish from each group were sampled immediately after exposure and at 1, 24 and 48 h post-exposure for blood collection; then they were killed, and the brain, gills, liver and kidneys were obtained for oxidative stress analyses. Air exposure and collection time led to changes in haematological, biochemical, gasometric and electrolytic parameters as well as those in oxidative stress in tissues. The fish modified their physiological parameters when subjected to stress by air exposure for 30 or 60 min, reestablishing baseline conditions at 48 h after air exposure, even when maintained in water at suboptimal temperature.