Changes in Growth and Feeding Characteristics during Early Ontogenesis in Threadsail Filefish, Stephanolepis cirrhifer.

Abstract

We investigated the growth and feeding characteristics of threadsail filefish, Stephanolepis cirrhifer, during early ontogenesis. The growth indices of hatchlings fed compound feed were measured from 0 to 50 days post hatching (dph). The absorption time of the yolk sac and oil globule, as well as the rate of first feeding were measured to characterise the early growth stage and determine the point-of-no-return (PNR). Feeding characteristics and rhythms were investigated under a light/dark cycle and under continuous light. Growth indices increased significantly at 24, 28, 30, 40, 45, and 50 dph. The yolk sac and oil globules were completely absorbed before 4 dph, indicative of a short mixed-nutrition period at 3-4 dph. Under starvation conditions, the first feeding rate was highest (86%) at 0.5 dph and then decreased to 53.3% at 1.5 dph and 26.2% at 2 dph, suggesting that the PNR occurs at 1.5-2 dph. The feeding peak appeared at 15:00-18:00 and under light conditions, while the feeding trough appeared at 0:00-3:00. Compound feed supplied adequate nutrition for early growth and development. The peaks and troughs of feeding times were indicative of daytime feeding behaviour. These results provide guidance for successful rearing of filefish seedlings and juveniles.