This study reports the stress responses of matrinxã after chasing. Juvenile fish (26.7±6.7 g) were adapted to 100L plastic boxes and submitted to the treatments: Control (no chasing), Chasing for 2 min, Chasing for 5 min, Chasing for 10 min (four boxes/treatment, 32 fish). Blood was drawn 15, 30 and 60 min after chasing to determine levels of cortisol, glucose, sodium, chloride, potassium, calcium, hematocrit, hemoglobin, erythrocytes number and osmolality. Matrinxã responses after forced swimming did not show the typical stress responses. There were no changes in blood cortisol, glucose, potassium and calcium levels in fish from any treatment until 60 min after chasing. Blood chloride levels were lower 15 min after chasing while the lowest levels of sodium were registered 60 min after the forced swimming. Osmolality dropped 30min after chasing, regardless the period of chasing. The intense swimming did not affect hematological indicators confirming the other physiological indicators. The results suggest that the intense swimming provoked by chasing up to 10 min was not intense enough to promote stress responses in matrinxã indicating that the species is very resistant to the farming handling.
Forced swimming; Stress; Matrinxã; Capture; Cortisol
