A research team has found that adding mulberry branch-derived biochar to feed can improve intestinal health and water quality in largemouth bass aquaculture without significantly changing fish growth performance. In a 42-day feeding trial, moderate dietary biochar levels enhanced digestive enzyme activity, strengthened antioxidant and intestinal barrier-related gene responses, reshaped gut microbiota, and reduced harmful nitrogen compounds in aquaculture water. The findings suggest that agricultural biomass waste, such as mulberry branches, could be converted into a functional feed additive for healthier and more sustainable fish farming.
Biochar is a carbon-rich material produced by heating biomass under oxygen-limited conditions. It has been widely studied as a soil amendment because of its porous structure, large surface area, and capacity to adsorb pollutants and improve nutrient use. More recently, researchers have examined biochar as a feed additive in livestock and aquaculture, where it may support digestion, regulate microbes, and reduce environmental stress. However, most previous work has focused on soil and atmospheric effects, while less is known about how dietary biochar affects aquaculture water quality. In intensive largemouth bass farming, uneaten feed, feces, and nutrient waste can damage water quality and threaten fish health, making cost-effective and eco-friendly feed strategies urgently needed.
A study (DOI: 10.48130/bchax-0026-0010 ) published in Biochar X on 01 May 2026 by Xiang Li & Hailong Wang's team, Foshan University, reports that 10–20 g kg −1 dietary mulberry branch biochar offered the best combined benefits for gut health and water quality.
To test the effects of mulberry branch-derived biochar, the researchers prepared biochar from mulberry branches pyrolyzed at 550 °C under oxygen-limited conditions, then ground and sieved the material before adding it to experimental diets. A total of 480 healthy largemouth bass with an initial average weight of 3.31 ± 0.01 g were randomly assigned to four diet groups containing 0, 10, 20, or 40 g kg −1 biochar, with four replicates per treatment and 30 fish per replicate. The fish were fed for 42 days. At the end of the trial, the team measured growth indices, intestinal morphology, digestive enzyme activity, intestinal gene expression, gut microbial diversity and composition, and water quality indicators, including total nitrogen, ammonia nitrogen, and nitrite nitrogen.
The results showed that biochar supplementation did not significantly affect overall growth performance, indicating that the additive did not impair normal growth. However, fish fed 20 and 40 g kg −1 biochar showed significantly higher intestinal trypsin and amylase activity, suggesting improved digestive capacity. The 10 g kg −1 group showed significant upregulation of IL-10, sod, and Occludin, genes associated with anti-inflammatory responses, antioxidant defense, and intestinal barrier function. Microbiome analysis further showed that all biochar-fed groups had significantly higher Chao1 and Ace richness indexes than the control group. Biochar also reduced the Firmicutes/Bacteroidetes ratio and decreased the relative abundance of potentially harmful bacteria such as Plesiomonas and Mycoplasma. In water quality tests, 10 and 20 g kg −1 biochar significantly reduced ammonia nitrogen and nitrite nitrogen, with day-42 ammonia nitrogen reductions of 60.7% and 49.3%, respectively, compared with the control. Nitrite nitrogen was also sharply reduced, especially in the 10 g kg −1 group.
Overall, the study indicates that mulberry branch-derived biochar can serve as a promising functional feed additive in largemouth bass farming. Although higher supplementation may alter microbial balance and should be used cautiously, moderate inclusion levels, especially 10–20 g kg−1, improved intestinal function, reduced potentially pathogenic bacteria, and helped control nitrogenous pollutants in aquaculture water. By linking fish health management with agricultural waste reuse, the work provides a practical strategy for greener aquaculture production.
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References
DOI
Original Source URL
https://doi.org/10.48130/bchax-0026-0010
Funding information
This research was funded by the High-level Guangdong Agricultural Science and Technology Demonstration City Construction Fund City Institute Cooperation Project (2220060000054, 2220060000050); Guangdong Academy of Agricultural Sciences Aquatic Research Center Project (XT202304).
About Biochar X
Biochar X (e-ISSN 3070-1686) is an open access, online-only journal aims to transcend traditional disciplinary boundaries by providing a multidisciplinary platform for the exchange of cutting-edge research in both fundamental and applied aspects of biochar. The journal is dedicated to supporting the global biochar research community by offering an innovative, efficient, and professional outlet for sharing new findings and perspectives. Its core focus lies in the discovery of novel insights and the development of emerging applications in the rapidly growing field of biochar science.
Biochar X
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Dietary mulberry branch biochar improves intestinal health and water quality in largemouth bass (Micropterus salmoides) aquaculture
1-May-2026
The authors declare that they have no competing interests.