Enhanced larval survival in orange‐spotted grouper ( Epinephelus coioides ) using optimized feeding regime

Abstract

Orange-spotted grouper, ideal finfish for mariculture, is constrained by the non-availability of sufficient seeds due to lower inconsistent larval survival. The present study attempted to establish a reliable larval rearing technique. Larvae fed with un-enriched or enriched rotifers (screened or unscreened) did not survive beyond 13 days post-hatch (DPH). Subsequently, copepod (Parvocalanus crassirostris) nauplii were supplemented at 0, 1, 2, 3 and 4 ml−1, in addition to enriched and screened rotifers, with live feed density of 12 ml−1, and this resulted in significantly improved survival at first feeding. Significantly higher (39.2%) larval survival on 16 DPH, with minimal size heterogeneity (13.13%), was observed in the group fed a combination of 2 copepod nauplii and 10 rotifers ml−1. However, mass mortality was observed between 18 and 21 DPH; and consequently, adult P. crassirostris were supplemented at 0, 0.25, 0.5, 0.75 and 1 ml−1 from 16 DPH along with rotifers, Artemia nauplii and artificial feed. Significantly higher larval survival on metamorphosis (40 DPH) was observed in the groups fed with 0.75 (17.71%) and 1 ml−1 (19.50%) P. crassirostris. Larval rearing protocol, with an average survival and length up to metamorphosis of 18.14% and 29.83 mm, respectively, during eleven cycles was developed. With consistent enhanced larval survival, the present study would facilitate mass scale seed production.