Effects of the timing of initial feeding on growth and survival of spotted mandarin fish Siniperca scherzeri larvae

摘要

The effects of delayed first feeding on growth and survival of spotted mandarin fish Siniperca scherzeri larvae were examined under controlled conditions. Morphometric characters [yolk-sac volume, oil globule volume, head depth (H-D), body depth (B-D), eye diameter (E-D), musculature height (M-H), mouth diameter (M-D) and total length (L-T)], body mass (M), specific growth rate (S-GR) and survival were evaluated under different first-feeding time (2, 3, 4 and 5 days after hatching). Larvae began to feed exogenously at 2 days after hatching (DAH) and the point of no return (P-NR) occurred between 5 and 6 DAH at 23 degrees C, range +/- 1 center dot 0 degrees C. The yolk volume of larvae first-fed at 2 days had a significant difference compared with that of larvae first-fed at 3, 4 and 5 days on 3 and 4 DAH. The larvae first-fed at 2 days achieved comparatively better growth performance than that of 3, 4 and 5 days. On 5 DAH, all morphometric characters had significant differences between 2 and 5 days and 2 and 4 days initial feeding, respectively. Total mortality was recorded on 9 DAH for the larvae first-fed at 5 days. On 12 DAH, significant differences were observed between 2 and 4 days and 3 and 4 days initial feeding for all morphometric characters. From 16 DAH to the end of experiment, all growth variables of the larvae first-fed at 2 days were significantly higher than those in other treatments. The S-GR (2-9 DAH) first-fed at 2 and 3 days were significantly higher than 4 and 5 day treatments, and the S-GR (9-16 DAH) first-fed at 2 days was significantly higher than 3 and 4 day treatments. There was no significant difference, however, of S-GR (16-28 DAH) among treatments. Survival rate was significantly higher at 2 days initial feeding (27 center dot 42%) when compared with 3 (15 center dot 96%) and 4 days (7 center dot 92%) initial feeding at the end of experiment. The present study suggests that the first feeding of S. scherzeri larvae should be initiated at 2 days after hatching for achieving good growth and survival.