THE EFFECT OF INITIAL STOCKING DENSITY ON GROWTH OF EUROPEAN CATFISH (SILURUS GLANIS L.) LARVAE UNDER CONTROLLED CONDITIONS
Dariusz Ulikowski, Izabela Borkowska
Inland Fisheries Institute in Olsztyn, Experimental Fish Hatchery „Dgał” in Pieczarki
ABSTRACT. Intensive initial rearing of European catfish (Silurus glanis) larvae was carried out. Initial densities of the fish were: 10, 15, 20, and 25 ind./dm3. The fish grew faster at lower densities. Average final individual body weights of the fish were: 1.71, 1.55, 1.42, and 1.27 g, and average body lengths (Lt): 5.60, 5.56, 5.51, and 5.30 mm, respectively. Survival was high and similar in all experimental groups (74.5-83.7%). The highest catfish production of initial stock number 1000 ind. was obtained at the lowest stocking density (10 ind./dm3). It was equal to 1.35 kg/m3. In all remaining groups: of 15, 20, and 25 ind./dm3 production was lower by: 17% (1.15 kg/m3), 13.8% (1.19 kg/m3), and 28.6% (1.05 kg/m3). All tested stocking densities (10-25 ind./dm3), and method of rearing used in the experiment are applicable to commercial conditions, but the period of rearing at higher densities (20-25 ind./dm3) should be limited to 12-14 days due to considerable decrease of fish condition.
Key words: EUROPEAN CATFISH, FISH, REARING, LARVAE, Silurus glanis, DENSITY DISTRIBUTION