The effect of delayed first feeding on growth and survival of yellowfin seabream (Acanthopagrus arabicus) larvae

Abstract

The effect of different initial feeding times (48 h, 72 h, 96 h, and 120 h after hatching) and food deprivation on the point-of-no-return (PNR), survival, and growth of yellowfin seabream Acanthopagrus arabicus larvae were studied under controlled condition. Growth parameters were investigated by evaluating morphometric (head depth, body depth, gut height, musculature height, eye diameter, total length, yolk, and oil globule volume) and gravimetric (dry weight) indices. The larvae commenced to feed exogenously at the mouth opening stage on day 2 after hatching (DAH) and reached PNR between 6 and 7 DAH at 19–20 °C. The time of initial feeding significantly affected the larval growth. From 3 DAH until the end of the trial period at 15 DAH, the growth (all morphometric indices and dry weight) of larvae started which earlier initial feeding start (48 h and 72 h after hatching) were significantly higher than that of 96 h (P < 0.05). Growth parameters were measured until 9 DAH in the larvae commenced feeding at 120 h, since complete mortality was recorded after this sampling point (at 12 DAH). During this period, the larvae showed significantly lower morphometric indices and dry weight compared with larvae in other initial feeding time treatments (48 h, 72 h, and 96 h). Yolk absorption in yellowfin seabream larvae was completed on 4 DAH regardless of the variances in the time of first feeding. Likewise, the oil globule was completely utilized on 5 DAH in all initial feeding trials. No significant differences were noticed in yolk volume and oil globule absorption between different treatments. At the end of the trial at 15 DAH, the survival rate was significantly higher for larvae began first feeding at 48 h (35.67 ± 7.01%) and 72 h (36.48 ± 4.72%) when compared to 96 h first feeding larvae (13.10 ± 2.62%)(P < 0.05). The findings from the current study reveal that the first feeding of yellowfin seabream larvae can be initiated up to 72 h after hatching with no significant differences in growth and survival rate.