The present study found evidence to suggest that rearing rainbow
trout ina current caused a decrease inthe amount of energy required for
maintenance. Potentially this allows for a larger fraction of dietary energy
intake to be allocated towards growth. As the metabolic scope of animals
was unaffected the magnitude of such an effect is not clear. During peak
digestion and absorption of a single pelleted meal (corresponding to 2%
body mass), rainbow trout double their metabolic rate (Eliason et al.,
2008). Compared to the present study, this corresponds to a 25%
utilisation of metabolic scope. Therefore, in terms of growth, it may be
more beneficial to reduce maintenance costs rather than increasing MS.
The study emphasises the beneficial effects of rearing in a current,
producing fish with a greater physiological quality. Our results also
demonstrate that as long aswater quality is not compromised, rearing at
high densities does not negate these benefits. The absence of any
significant changes to the haematological profile, suggests that rearing at
high density is not a stressful condition in itself