Effect of a rotifer and artemia on survival and growth performance of gilthead seabream Sparus aurata larvae.

An experiment was carried out in order to study the effect of a rotifer Brachionus plicatilis and encapsulated Artemia nauplii as a live food on survival rate and growth performance for gilthead sea bream Sparus aurata larvae. Gilthead sea bream larvae (20 days old) with body length and weight of (7.3 + 0.20 mm) (5.4 + 0.10 mg) respectively, were stocked in eight white fiberglass tanks (each of 1 m^3 volume) at a density of 1,200-larvae/ tank. Four treatments were tested as follows, 1) low rotifers and low artemia (LRLA); 2) high rotifers and low artemia (HRLA); 3) low rotifers and high artemia (LRHA); and 4) high rotifers and high artemia (HRHA) for 24 days (5, 25 rotifers and 50, 250 artemia /ml, during the periods 1st, 8th, 9th, 16th, 17th and 24th days of the feeding experiment). The results showed that the survival rate of S.aurata larvae significantly (P 0.05) improved with the application of the experimental program by feeding a high mixture of rotifers and artemia. Feeding of higher levels of rotifers and artemia increased the survival rate of S. aurata to 48.96%, however, the lower levels of both resulted in only 12.17 % survival rate. Other intermediate treatments of HRLA or LRHA resulted in better improvements in the survival rates (19.08 and 32.21% respectively) of S. aurata larvae. The results clearly showed the significant role of higher levels of encapsulated A. nauplii as a live food for saving the life of S. aurata larvae as compared with rotifers. Values of growth performance of S. aurata larvae (gain in length and weight; average daily gain in length and weight; and specific growth rate, (SGR %) significantly (P 0.05) increased with increasing the levels of live food from both rotifers and artemia. The results clearly showed the superiority of the higher levels of live artemia in enhancing growth performance of S. aurata larvae than rotifers. Finally, a suitable live food program to improve the survival rates of S. aurata larvae by feeding high levels of rotifers and artemia could be recommended.