Optimization of sustaining swimming speed of matrinxã Brycon amazonicus: performance and adaptive aspects

Abstract

Deleterious changes in metabolism, growth performance and body composition may be observed if fish are constrained to swimming continuously or intermittently at over-speeds. This study evaluates effects of four water speeds on growth, body composition and hematologic profile of juvenile matrinxã, Brycon amazonicus. Fish (33.3 ± 0.9 g and 13.44 ± 0.1 cm) were held for 90 days in five water speeds (0.0 - control, 1.0, 1.5, 2.0 and 2.5 body lengths per second - BLAt swimming speeds ranging on 1.0 and 1.5 BL s–1, in fish growth was 20% higher. Hemoglobin and red blood cells at 1.5 BL s–1 increased 24% and 18% respectively; hematocrit was 17% higher in all exercised fish; protein content of white muscle at 1.0 BL s–1 was 2% higher; lipid deposition in red muscle at 1.0 BL s–1 was 22% higher and water retention 3% lower. Crude energy levels enhanced 10% in all exercised fish; liver water retention was 6% lower at 1.0 BL s–1; liver lipid composition was 29% higher than control and 34% higher than 1.5 BL s–1; liver crude energy increased at 1.0 BL s–1 as compared with control and 2.5 BL s–1. Lipid deposition in ventral muscle was 9% higher at 2.0 BL s–1. Although high lipid deposition of matrinxã has been achieved in moderate swimming speeds, lipids may be the main fuel source to maintain the metabolic demands of exercised matrinxã. The best water flow speed for optimized growth of matrinxã ranged on 1.0 and 1.5 BL s–1.