The aim of the study was to determine the effect of increased stocking density on the growth and survival of larval asp, Aspius aspius (L.), and European chub, Leuciscus cephalus (L.), during mass rearing under controlled conditions. Fish larvae were obtained during artificial spawning at a hatchery. The larvae were reared for 21 days in a semi-closed recirculating system at a water temperature of 25°C. They were stocked at four densities (50, 100, 150, and 200 indiv. dm-3) and were fed freshly hatched Artemia sp. nauplii. The fastest growth rate for both species was obtained at the smallest stocking density (ITL = 0.67 and 0.58 mm d-1 for asp and chub, respectively). The highest mortality of larval asp was recorded at the density of 200 indiv. dm-3 (11.68%), and for chub at the density of 50 indiv. dm-3 (40.4%). The results obtained indicated that the stocking densities applied do not have an impact on larval growth or survival in the first week of rearing.
