Oxygen consumption (OC) was measured for 24 h in juvenile turbot, Psetta maxima (L.) using flow-through respirometry to examine the influence of salinity on energy metabolism. Turbot [164 g mean initial body weight (BW)] were reared at 16.5 AE 0.2°C and three different salinities (10, 20, 30 g L À1 ). Digestible and metabolizable energy requirements for maintenance (DE m ; ME m ) as well as the respective efficiencies of energy utilization for growth (k g (DE) ; k g (ME) ) were identified using different feeding levels (0.3, 0.6, 0.9 g kg À1 metabolic BW) and applying linear regression analysis. We found that nutrient and energy digestibilities decrease with an increasing salinity. DE m and ME m were 14.9-20.2 and 13.3-18.3 kJ kg À0.8 day À1 and k g (DE) and k g (ME) 0.82-0.87 and 0.87-0.91, respectively. No differences were observed in DE m , ME m , k g (DE) and k g (ME) between salinities, although these parameters were low at a high salinity (30 g L À1 ). Turbot showed the most favourable combination of DE m and k g (DE) (ME m and k g (ME) ) at a salinity of 20 g L À1 and at 30 g L À1 growth and energy utilization were reduced at high energy intake. However, energy requirements for iono-and osmoregulation were small.

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