Biological performance of red porgy (Pagrus pagrus) larvae under intensive rearing conditions with the use of an automated feeding system

Pagrus pagrus is one of the promising species for the industry in the Mediterranean but its rearing is still far from satisfactory. In the present work, the conditions and results of larval rearing with the use of an automatic feeding system are presented. Eight populations were reared for 20 days with the 'pseudo green water' methodology in two successive trials. Larvae were fed enriched rotifers during the entire rearing period, a mixed diet of rotifers and Artemia (Instar I when larvae reached 5mm in length, replaced by Instar II after larvae reached 5.5 mm) and a formulated diet ( after day 16 post hatching). A computerized system for feeding management was used. A total of 388,000 eggs were incubated and after 20 days, 237,973 larvae (TL = 6.96 +/- 0.17 mm) were produced with a survival rate of 61.4 +/- 6.3%. Individuals grew in terms of wet weight with an exponential rate of 0.167 +/- 0.008 daily (R-2 = 0.983) with no variations between replicates. Mean individual daily consumption at first feeding (day 4-post hatching), was 0.20 +/- 0.06 mg of food (0.03 +/- 0.01 dry weight), that is, 180-300 rotifers, while on day 20, consumption increased by 10 (2.081 +/- 0.106 mg and 0.276 +/- 0.014 in wet and dry weight, respectively). When compared with sea bream, consumption was higher by approximately 3-4-fold. The mean food conversion ratio of the experimental period was 4. In comparison with sea bream larviculture, food consumption of red porgy is higher, and a different feeding strategy is required to satisfy the requirements of the larvae.