Impact of increased flow rate on specific growth rate of juvenile turbot (Scophthalmus maximus, Rafinesque 1810)

The effect of flow rate on growth was investigated in juvenile turbot. Fish with a mean (SD) initial weight of 102 (10.4) g were reared at 6 different flow rates, equaling 1, 2, 3, 4, 6 or 8 tank volumes/h in 196 L tanks during 29 days at 18 ± 0.29 °C, a salinity of 18.0 ± 0.77‰ and a pH ranging from 6.02 to 7.21. Total ammonia nitrogen, dissolved oxygen, pH, temperature and free carbon dioxide levels were monitored during the experimental period. Results show that increasing the flow rate promotes the growth of turbot up to a flow rate of 4.7 tank volumes/h. Accumulation of ammonia and carbon dioxide and oxygen levels in the tanks were affected by the treatments. It is concluded that increased flow rate resulted in higher SGR of juvenile turbot, possibly explained by differences in carbon dioxide levels.