Influence of Dietary Carbohydrate Types on Growth Outcomes and Microbial Community Structure in Biofloc-Reared Stinging Catfish (Heteropneustes fossilis)

Abstract

Aquaculture plays a crucial role in global food and nutritional security, with biofloc technology (BFT) emerging as a sustainable approach to enhance productivity and environmental health. BFT improves water quality and feed efficiency by converting waste nutrients into microbial biomass beneficial to cultured species. Heteropneustes fossilis, a hardy and high-value catfish, holds strong potential for integration into BFT systems to promote growth and gut health. The present study evaluated the effects of different carbohydrate sources on water quality, growth performance, and microbial communities in H. fossilis culture. The 120-day experiment was conducted in 450 L tanks with five treatments: three biofloc groups (T1-molasses, T2-rice flour, and T3-molasses+ rice flour), one probiotic group, and a single control. Fingerlings (2.86 ± 0.5 g) were stocked at a density of 700 m^-³ (n = 210 per tank).
Results indicated significant improvement in water quality parameters across all biofloc treatments compared to the control, with treatment T3 (a combination of molasses and rice flour) exhibiting the most pronounced effects. T3 optimised floc volume (34.77 ± 0.30), enhanced microbial diversity and supported the highest growth and survival rates (1.90 ± 0.02 & 96.35 ± 0.7). Key performance
indicators, including percentage weight gain and feed conversion ratio (782.52 ± 25.52 & 1.60 ± 0.10), were superior in T3, highlighting the synergistic benefits of mixed carbon sources. Moreover, T3 promoted greater proliferation of Bacillus spp. and
total heterotrophic bacteria in both water and gut samples, improving nutrient utilisation and fish health. These findings demonstrate that mixed carbohydrate-based biofloc systems can sustainably improve water quality, microbial stability, and growth performance in H. fossilis aquaculture.