Enhanced larval survival in orange‐spotted grouper (Epinephelus coioides) using optimized feeding regime
2022
Ranjan, Ritesh | Megarajan, Sekar | Xavier, Biji | Bhaskaran Pillai, Santhosh | Bathina, Chinnibabu | Avadhanula, Ravi K. | Ghosh, Shubhadeep | Ignatius, Boby | Joseph, Imelda | Gopalakrishnan, Achamveettil
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.
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