Studies on the Formation and Hatching of Fertilized Eggs of the Rotifer Brachionus plicatilis-VIII. Dietary Value of Neonates from Rotifer Brachionus plicatilis Resting Eggs for Red Sea Bream Larvae.

Abstract

The dietary value of hatched neonates from the marine rotifer Brachionus plicatilis resting eggs was investigated through larval rearing trials of red sea bream Pagrus major and chemical analysis. Rotifer resting eggs were mass-produced in 50m3 tanks by feeding Nannochloropsis oculata and baker's yeast. Eggs were preserved at 5°C under total darkness for 1-2 years and hatched at 23°C under continuous light. After nutritional enrichment with the use of N. oculata and squid oil, hatched neonates or commonly mass-cultured rotifers (control) were fed to fish larvae. Newly hatched fish larvae were stocked in 100l (80l in water volume) polycarbonate tanks at 15 or 30/l. No significant differences in larval growth (notochord length and dry weight) were found on Day 20 between groups fed on neonates from resting eggs and those fed on control rotifers. The survival rate of fish larvae fed on neonates (38%) were, however, significantly lower than the group fed on control diets (69%). This may be due to the fact that the uniform lorica size and synchronous growth of neonates during the enrichment culture after simultaneous resting egg hatching did not fit the mouth size of the fish larvae. The amount and composition of fatty acids of neonates were the same as those of the control rotifers.