Moulting and growth of mangrove crabs Scylla olivacea (Herbst 1796) with injection of phytoecdysteroids and artificial feed

Abstract

Moulting in crabs can be accelerated by adding moulting hormone. Phytoecdysteroids are an active compound found in certain plants, for example amaranthus, that are analogous to the moulting hormone in crustaceans. The aim of this study was to determine the effect of phytoecdysteroid administration through injection and artificial feed on moulting and growth of mud crabs (Scylla olivacea). Mud crabs with carapace width 61–62 mm and weight 50–51 g were reared in individual crab boxes with dimensions 25×20×20 cm. The selected crabs were injected with amaranthus extract at a dose of 1 mL/crab (I), then placed in the crab boxes and kept in a pond. Amaranthus leaves were dried in an oven at 60°C for 24 hours, ground using a hammer mill, and mixed with other feed ingredients. Different doses of amaranthus flour were applied: 0% (control), 10%. 12.5%, 15%, 17.5% and 20%. Moulting and growth data were analysed for a variance. The results showed that the administration of phytoecdysteroids from amaranthus by injection and through artificial feed had no effect on the percentage of mud crabs moulting, survival rate, growth, and feed conversion value. The mud crabs were not able to take full advantage of the artificial feed provided because of the inappropriate size of the feed and the fragile structure that cause wasted and uneaten feed.