The effects of different stocking densities on the growth and survival rate of ide (Leuciscus idus) and barbel (Barbus barbus) during larval rearing in RAS

Abstract We examined the effects of different stocking densities on the growth and survival rate of ide ( Leuciscus idus) and barbel ( Barbus barbus ) larvae. The fish were reared for 21 days in RAS. Ide larvae were stocked at four densities (25, 50, 75, and 100 larvae l −1 ), while for barbel, the effects of two different stocking densities (50, 100 larvae l −1 ) were examined. At the beginning of the experiments, 9 days post-hatch, total length, and body weight of ide larvae were 10.36 ± 0.36 mm and 2.39 ± 0.51 mg, respectively. The same parameters for the barbel were 13.06 ± 0.92 mm and 10.98 ± 1.77 mg. Initially, the fish were fed with live Artemia nauplii, and then they received dry food. The mean final length and weight of ide larvae (30 days post-hatch) across all treatments were 15.12 ± 1.76 mm and 26.85 ± 7.58 mg, respectively. The average survival rate was 82.7 ± 6.25%. Increasing stocking density did not affect adversely the examined indicators. The mean final weight of barbel larvae across all treatments was 629.3 ± 161.6 mg without a significant difference between the two groups. Significantly higher final length was measured in the 50 larvae l −1 group (20.04 ± 2.08 mm) compared to that of the 100 larvae l −1 group (18.83 ± 2.46 mm). High survival rates were recorded for both groups (above 90%) without differences. Pre-nursing of ide and barbel larvae in RAS resulted in perfectly developed offspring with extremely low mortality.