Routine exposure to biometric procedures in fish farming reveals differences in stress response in tambaqui and hybrid tambatinga

Abstract

The physiological stress responses of tambaqui and hybrid tambatinga were evaluated after subjecting the fish to routine practices in a breeding system such as periodic biometric procedures. For 270 days of culture, the fish underwent monthly biometric measurements, and, at the end of the period, blood was collected at six sampling times (before, immediately after, and 2, 24, 48 and 72 h after biometric measurements) for the evaluation of physiological indicators of stress. Tambatinga is more susceptible to stress because it presented higher levels of cortisol and glucose in the bloodstream after handling and took longer to recover its basal physiological state for these parameters. However, the low cortisol levels observed in both species suggest that the fish were familiar with biometric procedures, resulting in a less intense response. Handling led to an increase in the cellular volume of erythrocytes in tambaqui, resulting in a change in hematocrit and a decrease in hemoglobin concentration. Hypochloremia was found in both species only 72 h after handling. Biometric procedures promote hormonal, hematological and hydroelectrolytic changes in the tambaqui and hybrid tambatinga, but when routinely adopted, at regular intervals, they elicit stress responses of lower magnitude.