Use of enalapril maleate on swimming behavior and during osmotic shock in juveniles of the grouper Epinephelus marginatus Lowe, 1834 (Teleostei: Serranidae)
The grouper (Epinephelus marginatus Lowe, 1834) is a species of marine fish that presents rapid growth and during its life cycle they can migrate to environments with different salinities. The renin-angiotensin system (RAS) has an important role in stress, with Angiotensin II being its active molecule. The use of angiotensin-converting enzyme (ACE) inhibitors can influence stress, decreasing it. The aim of the study is to evaluate the effect of enalapril maleate (angiotensin I-converting enzyme inhibitor) in captivity and in osmotic shock in which it is a stressful event. 120 groupers were used, in two recirculation systems, with three tanks each, with one group receiving the pelleted commercial feed and the other receiving added 10mgKg-1 of enalapril maleate for 30 days.Before the end of the experiment, in 20 days, each tank was filmed, 5 minutes each and 1 minute with a 20X zoom to verify the swimming behavior through the swimming speed and then the images were processed. At the end of the experiment, blood (n = 15 for each treatment) was collected to measure hormonal (cortisol, norepinephrine and adrenaline), metabolic (glucose) and ionic (sodium, potassium and calcium) parameters before shock. The osmotic shock was 10 minutes in fresh water and the blood was removed after 10 min, 2 hours and 6 hours, which were the analyzed times. The swimming speed data were subjected to Student's T test and the shock by two-way ANOVA to Tukey's post-hoc test with significance level P <0.05. Enalapril maleate decreased swimming speed significantly and reduced hormonal parameters,metabolic and ionic effects during osmotic shock showing that the reduction in swimming speed may be due to the reduction of cortisol and glucose in the treaty compared to the control in the osmotic shock experiment, and enalapril maleate can be used as a mitigation of stress in captivity and in salinity changes in grouper.