Growth, feeding and oxygen consumption of Senegalese sole (Solea senegalensis) juveniles stocked at different densities

Four different stocking densities (2, 7, 15 and 30 kg m− 2) of the flatfish Senegalese sole (Solea senegalensis) were assayed using 70 g juveniles throughout a 60 days culture period. No differences were found with regards to growth parameters in terms of biomass production or body weight gain as a function of fish stocking density. Ingested feed increased from 0.134 ± 0.01 to 0.201 ± 0.01% (relative gut content) as stocking density rose from 2 to 30 kg m− 2, indicating that, while keeping constant feed ration, crowding leads to higher feed consumption. The higher feeding activity associated with density coincided with increased metabolic rates, as revealed by higher levels of oxygen consumption. In the absence of feed, oxygen consumption remained similar under all fish densities tested. On the other hand, sole density did not affect to size hierarchies concerning feeding, with no significant correlation (P > 0.1) between ingested feed and fish size under all experimental conditions. During the whole experimental period no aggressive behaviour among stocked soles was detected in any instance. Overall results from this work show S. senegalensis to be an adequate species for growing using stocking densities that are compatible with intensive production systems.