Alternatively, the maintenance of metabolic rate across all acclimation salinities could suggest that costs of osmoregulation in inanga are low. Estimations of the cost of osmoregulation in SW in other species range from 2.4% to 15% of the resting metabolic rate depending on the fish species. A cost at the low end of this range for inanga would have been difficult to detect under the methodological approach used. Furthermore, changes in locomotion or other activities between fish acclimated to different salinities could easily obscure trends related to varying osmoregulatory costs. In the current study salinity-dependent activity patterns were not specifically measured, but no obvious changes were observed.