The effect of carbon dioxide on growth and energy metabolism in pikeperch (Sander lucioperca)

Pikeperch (Sander lucioperca) is a popular fish for human consumption and decreasing wild catches increase the demand for aquaculture production. Limited knowledge of the species' requirements under intense recirculating aquaculture system (RAS) culture conditions has motivated this study to focus on the effect of elevated carbon dioxide (CO2) levels on pikeperch metabolism. The trial was conducted in a recirculating aquaculture respirometer system with pikeperch (average body weight 251.9 g) and three hypercapnia regimes over 58 feeding days. Food grade CO2 gas was gradually added to the medium (15 mg L− 1) and high (30 mg L− 1) treatments while no gas was added to the low treatment (hence 4 mg L− 1). Fish were fed daily for 10 min with a commercial diet (ALLER Metabolica). O2, T, pH, CO2 were measured individually for each tank and logged every 2 h to calculate oxygen consumption rates of each treatment. Total Ammonia-Nitrogen was measured monthly for individual tanks and used to calculate TAN excretion. Results showed a linear decrease of 6% in final body weight with increasing CO2 levels between the low and the high CO2 treatment. Feed intake was linearly increased after four weeks of the experiment from 0.97 ± 0.07% in the low CO2 treatment to 0.86 ± 0.03% in the high CO2 treatment but the effect faded after eight weeks, indicating a habituation to the hypercapnia conditions. High levels of CO2 were associated with reductions in haematocrit and metabolic oxygen consumption. The results suggest that adult pikeperch can survive carbon dioxide concentrations of up to 30 mg L− 1 when other water quality parameters are in acceptable levels but will be affected in metabolism already at moderate CO2 levels of 15 mg L− 1.