Synergistic Carbon Source Utilization in Biofloc Aquaculture of Common Carp (Cyprinus carpio) : Impacts on Growth, Health, and Environmental Parameters

Nandini Rai ¹ J M Julka ¹ Akshaya Panigrahi ² Sofia Priyadarsani Das ^3*

• ¹ Shoolini University, Solan, Himachal Pradesh, India
• ² Central Institute of Brackishwater Aquaculture (ICAR), Chennai, Tamil Nadu, India
• ³ National Taiwan Ocean University, Keelung, Taiwan

A 90-day study was conducted to investigate the impact of different carbon-to-ratios, achieved through different combinations of jaggery and corn flour, rice flour, or rice bran, on common carp (Cyprinus carpio) fingerlings in a Biofloc system. The results indicated that the addition of carbon sources, particularly jaggery and rice flour, significantly ameliorated water quality parameters by reducing total ammonia nitrogen, nitrite, and nitrate levels. This improvement was attributed to the increased Biofloc volume, which facilitated organic matter degradation and nutrient uptake. Among the experimental groups, the group fed with a combination of jaggery and rice flour exhibited the most favourable outcomes. These fish demonstrated superior growth performance, as evidenced by higher final weight, weight gain, and specific growth rate compared to the control group. Additionally, the combination of jaggery and rice flour group displayed the highest levels of crude protein and crude lipid in their body composition. Histopathological analysis revealed improved hepatic and intestinal health in fish from this group, suggesting that the combination of jaggery and rice flour promoted a healthier gut. Microscopic examination of the Biofloc revealed a diverse morphology such as rod shape in jaggery and rice flour, spherical peanut shape in Jaggery: corn flour. However, combination of jaggery and rice flour group exhibited a unique Biofloc structure that may have contributed to its superior performance. Furthermore, gene expression analysis revealed elevated levels of immune-related markers in fish reared in the combination of jaggery and rice flour group, indicating a strengthened immune response. The Biofloc system supplemented with jaggery, and rice flour demonstrated significant improvements in water quality, growth performance, body composition, histological structure, and immune function of common carp fingerlings.