Exercise in fish is known to manipulate a number of physiological functions. It has been shown that exercise increases the growth rate of salmonids fishes, and it has been hypothesized that this is due to energetic advantages of swimming. We have recently shown that this is not the case; that in fact is much more costly to be reared in moving water (i.e. be forced to swim) that it is to be reared in still water. The explanatory mechanisms for increased growth must therefore lie elsewhere. The purpose of the project is to determine how swimming influences for example macro nutrient utilization, appetite, feed conversion, etc. The project can be performed in collaboration with the feed industry.