Effects of intense exercise training on rainbow trout growth, body composition and metabolic responses.

Cultured fish are bound to experience a variety of potentially stressful situations. In principle, stress may be reduced by adapting fish to intense exercise. This article addresses the effects of chase-induced intense exercise training on rainbow trout. Training reduced fish growth and worsened their nutritional use of food, but had no effect on food intake, biometry or body composition, indicating that a significant fraction of the diet's energy was being used for exercising rather than growth. Regarding metabolic responses, training significantly counterbalanced lactate, glucose and cortisol plasma concentration increases induced by intense exercise, while completely abolishing that of plasmatic proteins. These data suggest that this type of training adversely affects fish growth and food conversion, whereas it improves their metabolic response capacity and reduces the stress component of forced exercise.