Abstract
The present study aimed to evaluate the effects of different carbohydrate sources on water quality, growth performance, and microbial communities in Heteropneustes fossilis. The experiment was conducted for 120 days using 450 L tanks, withfive treatments consist of three biofloc groupss, only probiotic group and a control group. H. fossilis fingerlings (2.86 ± 0.5 g) were stocked at a density of 700 individuals m⁻³ (n = 210 per tank). The results indicated significant improvements in water quality parameters in all biofloc treatments compared to the control, wherein T3 treatment (a combination of molasses and rice flour) showed the most pronounced effects. The treatment, T3 optimized floc volume and enhanced microbial diversity was favorable for growth and survival of the fish. Growth performance metrics including harvested weight, net weight gain, specific growth rate, and feed conversion ratio were highest in the treatment T3, demonstrating the synergistic benefits of utilizing mixed carbon sources. Furthermore, the treatment T3 supported the highest proliferation of Bacillus spp. and total heterotrophic bacteria in both biofloc water and gut samples, contributing to better growth and survival. These findings underscore the potential of biofloc systems to sustainably enhance aquaculture productivity, particularly through the strategic application of mixed carbon sources as a means to improve water quality, microbial health, and growth outcomes in H. fossilis culture.
Keywords: Biofloc technology (BFT), Carbon sources, Probiotic bacteria, Growth performance, Aquaculture productivity