Growth and feed utilization by golden grey mullet (Liza aurata) in a coastal lagoon ecosystem, fed compound feeds with varying protein levels

Abstract

The effects of complimentary compound feeds with varying protein levels on growth performance, feed utilization, and whole body composition were studied in golden grey mullet, Liza aurata. Fish of initial weight 51.1±5.2 g were raised in hapas in a coastal lagoon and fed four iso-energetic diets containing 25%, 30%, 35% or 45% of crude protein for 20 weeks. L. aurata reared on the experimental diets showed relatively low growth rates (SGR ranged from 0.40 to 0.48%/day, and feed utilization parameters (FE ranged from 0.27 to 0.34) among dietary groups consistent with the known slow growth rate of the species. The growth performance and feed utilization of L. aurata was not significantly affected by dietary protein level, despite the fact that there was a trend indicating better fish growth and feed efficiency with increasing dietary protein level. This is indicative of the low protein requirements of L. aurata, although it could be that higher dietary protein concentrations could possibly improve growth performance. The farming of low-trophic species such as L. aurata allows under-utilized trophic resources to be better exploited for fish production. Thus any future advances in understanding the nutrition and feeding of L. aurata under culture conditions, could improve further the potential of this species, especially in regional and coastal aquaculture.