Pikeperch (Sander lucioperca) is one of the most appreciated fish species found in many European countries, in natural waters and in fish farms as well. This species started recently to be reared into recirculating aquaculture systems (RAS) but the farming technology has to be improved continuously in order to increase the fish production and to reduce the production costs. The aim of this study was to test two polyculture variants of the pikeperch, with sterlet (Acipenser ruthenus) and with European catfish (Silurus glanis), in order to reveal the best candidate species to be reared together with pikeperch into the same tank, in RAS. The pikeperch and sterlet fingerlings used in our study were obtained in RAS, in the spring of the year 2017, from broodstok exclusively reared in RAS. At the study starting, the fish had 6 months and 5 months old, for pikeperch and sterlet, respectively. The European catfish fingerlings were obtained through artificial method using broodstock from ponds, and reared in RAS until the age of 4 months, when our study starts. The RAS used for the fish rearing had four tanks, with 1 cubic meter of water each. Two variants of polyculture were tested in replication: pikeperch with sterlet, and pikeperch with European catfish. The fish biomass of the secondary species represented about 21% from the pikeperch biomass in each variant. The fish were fed with dry food SUPREME-10, size 3mm (Coppens International, Nederland), the amount being calculated as 2.5% from pikeperch biomass, being adjusted twice per month. The main body traits (total length, standard length, maximum high and body weight) were measured at the beginning of the study, and afterwards twice per the month covering this preliminary study. Based on the data obtained after the measurements, the main bio-productive indices like Specific Growth Rate (SGR), Daily Growth Rate (DGR), Weight Gain (WG), Feed Eficiency (FE) and Feed Conversion Ratio (FCR), were calculated. The results revealed that both species used in our study as secondary species in polyculture with pikeperch, are suitable and could lead to a good valorization of the feed into RAS, but the polyculture of the pikeperch with European catfish seems to be more advantageous. Anyway, more studies should be carry out for a better understanding of all aspects linked to these polyculture formulas used for pikeperch farming in RAS.

pikeperch, polyculture, sterlet, European catfish, RAS

biology

Presentation: poster