Effects of different C:N ratios on growth and survival of spotted scat (Scatophagus argus) in the biofloc system

Abstract

The objective of this study was to determine the suitable C:N ratio  for growth and survival of spotted scat (Scatophagus argus) cultured in the biofloc system. The experiment was designed randomly with four treatments in different ratios of C:N such as (i) control treatment (without adding molasses); (ii) C:N=10:1; (iii) C:N=15:1; (iv) C:N=20:1, each treatment was triplicated. Spotted scat with average initial weight of 3.59 g were stocked in the 0.5m3 tanks at a density of 40 fish/m3 and cultured at salinity of 5 ppt. Molasses was used to create  and maintain biofloc formation in each treatment. After 4 months of culture, the spotted scat in the C:N=15:1 treatment had an average weight of 34.9 g and was the highest growth, highest survival rate, highest biomass, lower feed conversion ratio, and were significantly different (p<0.05)  from the other treatments. The lowest survival rate and the yield were found out in the control treatment. Thus, the spotted scat were cultured in the biofloc system with supplementation of molasses (C:N=15: 1) could be suitable for this species.