Variability in growth and moulting of early post-larval prawn, Macrobrachium rosenbergii, fed with enriched Artemia

Abstract

Macrobrachium rosenbergii, popularly known as the giant freshwater prawn (GFP), is a commercially important aquaculture species. However, its commercial production faces several challenges, including low larvae survival due to the unavailability of suitable feed. An adequate nutritional input can offer higher post-larval (PL) survival. Live feed, such as Artemia by itself is not nutritionally rich; however, offers the possibility to enrich it with a variety of nutrients. The present study was performed to compare the effect of four Artemia spp-enrichment regimes on growth, moulting, and survival of PL of GFP reared in individual compartments. This physical isolation of GFP aims to prevent cannibalism, prevent dominant hierarchies, and record individual moult-related data. The early PL was fed with Artemia enriched with Yeast (control-T1), Chlorella spp. (T2), commercially enriched Nannochloropsis (Nanno 3600™) (T3), egg custard mixed with cod liver oil (T4). All feeding treatments were performed in triplicates, with each replica containing five PLs, and each PL was placed in a separate container inside a tank. Most suitable water quality parameters to maximise the growth of GFP were maintained for the 30-day trial. The diet T3 had the highest protein content (59.55%) whereas the diet T4 had the highest lipid content (18.94%). The early juveniles in the T3 and T4 treatment groups attained maximum weight, 40.10 ± 1.24 mg and 39.29 ± 1.18 mg, respectively. The highest DHA:EPA for the enriched Artemia was obtained for the T4 group (0.49). The highest SGR and relative biomass gain were obtained in PL of the T3 group; the diet for the same contained DHA:EPA of 0.27. The Condition factor (K) for treatments other than the control ranged between 0.72 and 0.79. An overall survival of 91.6% was achieved in this trial. As per the moult observation, 80% of PL moulted more than three times. There was no significant difference in moult interval among treatments; however, the mean moulting frequency ranged between 2.85 and 3.79. The first, second, and third moult intervals ranged between 7.82 and 9.60, 7.31 and 8.89, and 7.13 and 8.50 days, respectively. The present study concludes that the commercial Nannochloropsis and egg custard-cod liver oil enriched Artemia feed protocol developed in this study enhanced the growth and survival of PL.