Afeeding trial was carried out to study the effect of different feeding levels on growth, feed conversion ratio (FCR), protein
and energy utilization, body composition arid cost benefit of rnarine rabbitfish, Siganus rivulatus fingerlings. Eight net cages, each one hold about 0.5 m3 with (1.0 x 1.0 x 0.5 m dimensions), were put in fiberglass basin and used to stock 10 fingerlings with an average of 3.42 g/fish initial size. Four different feeding levels (2, 4. 6 and 8% of biomass weight of fish) were tested in the experiment. Fish were fed on the experimental diet which contains 27% crude protein. The feed
was divided into two equal parts for 84 days feeding period. Fish were weighed every two week intervals and feed amounts were adjusted on the basis of the new fish weight. Results indicated that growth performance of S. rivulatus was
to be directly related to feeding levels. It was increased as feeding level increases. The specific growth rate (SgR) values were 1.03, 1.41, 1.74 and 2.02 %/day for fish received 2, 4, 6 and 8% feeding levels, respectively. However, feed conversion ratio (FCR) was improved by decreasing the feeding levels. The best FCR value was obtained at low
feeding level (2% of biomass weight). On the other hand, protein efficiency ratio (PER), productive protein value (PPV %) and energy retention (ER %) were declined with the increase of feeding levels. From economic view, low feeding level (2%) had lower feed cost and higher profit index than all tested feeding levels. This indicated that this level was economically recommended to be used in rabbitfish, S rivulatus feeding.