Aquacultural Engineering 91 (2020) 102123 Available online 15 September 2020 0144-8609/© 2020 Elsevier B.V. All rights reserved. The use of biochar in the production of tilapia (Oreochromis niloticus) in a biofoc technology system - BFT Godwin Abakari a , Guozhi Luo a, b, c, *, Haoyan Meng a , Zhang Yang a , Gilbert Owusu-Afriyie a , Emmanuel O. Kombat d, e , Elliot H. Alhassan f a Shanghai Engineering Research Center of Aquaculture, Shanghai Ocean University, Shanghai 201306, China b Key Laboratory of Fresh water Aquatic Genetic Resources, Shanghai Ocean University, Shanghai 201306, China c National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai 201306, China d Key Laboratory of Freshwater Fishery Germplasm Resources, Ministry of Agriculture, Shanghai Ocean University, Shanghai 201306, China e Department of Applied Biology, Faculty of Applied Sciences, University for Development Studies, P. O. Box 24, Navrongo, Ghana f Department of Fisheries and Aquatic Resources Management, University for Development Studies, P. O. Box TL 1882, Tamale, Ghana A R T I C L E INFO Keywords: Biochar Biofoc Technology (BFT) Oreochromis niloticus Nitrifcation Antioxidant activity DOC/TAN DOC/TN ABSTRACT The present study investigated the effectiveness of biochar as a water quality control agent and an alternative carbon source in a tilapia-based biofoc technology (BFT) system. Water quality parameters were measured following standard procedures (APHA, 1998) and fsh physiological indices were measured using designated ELISA kits. Data was analyzed using repeated measures ANOVA and one-way ANOVA. Two biochar treatments were employed i.e. B; only biochar, GB; biochar + glucose, while for the control (G) only glucose was added. Tilapia fngerlings were cultured for approximately 10 weeks with no water exchange. Signifcant reduction (p < 0.05) in dissolved oxygen (DO) level was observed in group G (5.99 ± 0.10 mg/L) compared to B (6.66 ± 0.12 mg/L) and GB (6.53 ± 0.56 mg/L). Notably, concentrations of total suspended solids (TSS) were signfcantly lower in the biochar treatments (B and GB) compared to the control (G). Additionally, alkalinity was signifcantly higher in G (156.47 ± 5.17 mg/L) compared to B (137.92 ± 3.83 mg/L) and GB (146.44 ± 3.87 mg/L). Levels of NO 3 - and total nitrogen (TN) were signifcantly higher in group B compared to G and GB. Also, signifcant difference was observed in PO 4 3- levels between B (30.81 ± 2.28 mg/L) and GB (22.70 ± 1.84 mg/L). The dy- namics of the water quality parameters revealed that heterotrophic assimilation and nitrifcation were active in maintaining the water quality. Overall, the result showed no signifcant differences (p > 0.05) in all the fsh growth parameters. Urea nitrogen measured in the fsh was signifcantly lower in B (3.85 ± 0.32 mmol/L) compared to G (5.40 ± 0.39 mmol/L) and GB (5.53 ± 0.39 mmol/L). Generally, there were no notable detri- mental effects of biochar application on fsh growth and physiological performance. 1. Introduction In the past decade, priority has been placed on inventing new, cost- effective, effcient and benefcial technologies in an attempt to meet the rising demand for aquaculture products (Ebeling et al., 2006). These technologies must be geared towards expanding the aquaculture in- dustry in a sustainable way (Crab et al., 2012). Genuine concerns have stood on the way of aquaculturists in the production strategies from growing at par with the rising global demand for these products. These include: environmental protection concerns, the need to reduce pressure on limiting natural resources of land and water and the call for inexpensive but sustainable technologies (Avnimelech, 2009; Avnime- lech, 2015). Biofoc technology (BFT) systems have emerged as practical and inexpensive means of meeting the above prerequisites of sustainable aquaculture development, and this is in line with the recommendation by Naylor et al. (2000), who indicated that new aquaculture systems should be designed to do little or no harm to the environment. BFT operates on the basis that inorganic nitrogen build-up, which is one of the major problems encountered in the aquaculture industry (Timmons et al., 2002), can be controlled by manipulating the carbon/ nitrogen ratio (C/N) in the system by the supply of external carbohydrates * Corresponding author at: Hucheng Ring Road, 999, Shanghai Ocean University, 201306, Shanghai, China. E-mail address: gzhluo@shou.edu.cn (G. Luo). Contents lists available at ScienceDirect Aquacultural Engineering journal homepage: www.elsevier.com/locate/aque https://doi.org/10.1016/j.aquaeng.2020.102123 Received 9 June 2020; Received in revised form 2 September 2020; Accepted 6 September 2020