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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Subtropical Plant Pathology Research » Research » Publications at this Location » Publication #425630
Research Project: Establishing Seedstocks for the U.S. Marine Finfish Industry

Location: Subtropical Plant Pathology Research

Title: Preliminary investigation on replacing fish meal with integrated multi-trophic aquaculture produced bioflocs in the diets of advanced Red drum (Sciaenops ocellatus, Actinopterygii) juveniles

Author
item Romano, Nicholas
item WILLS, PAUL - Harbor Branch Oceanographic Institute
item PAREDES, FERNANDO - Harbor Branch Oceanographic Institute
item RICHE, MARTY - Harbor Branch Oceanographic Institute
item NILLES, ZACHARY - Harbor Branch Oceanographic Institute

Submitted to: Aquacultural Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/14/2025
Publication Date: 5/16/2025
Citation: Romano, N.P., Wills, P.S., Paredes, F., Riche, M., Nilles, Z. Preliminary investigation on replacing fish meal with integrated multi-trophic aquaculture produced bioflocs in the diets of advanced Red drum (Sciaenops ocellatus, Actinopterygii) juveniles. Aquacultural Engineering. 111:102566. 2025. https://doi.org/10.1016/j.aquaeng.2025.102566.
DOI: https://doi.org/10.1016/j.aquaeng.2025.102566

Interpretive Summary: Biofloc technology (BFT) is when natural bacteria in the water transform otherwise toxic ammonia (produced from the fish) into nutritious particles. Thus, BFT is used in aquaculture systems to keep the water clean for the fish while also producing a feed ingredient that can potentially reduce reliance on expensive proteins in fish diets. In this study, bioflocs were collected from our in-house aquaculture system that has been an integral part of the system for over a decade, and the collected bioflocs were included in Red drum diets at the expense of fish meal by 25 or 50%, and with or without amino acid supplementations. Results showed bioflocs could replace fish meal by 25%, but actually provided superior growth to Red drum when amino acids were supplemented. This is remarkable considering bioflocs are a readily available resource that yielded approximately 1/4 of the food inputted to the system. The results provide farmers with a new method to maintain good conditions for the fish while at the same time producing a sustainable and inexpensive way to produce cheaper fish diets, which is often 50% of all operating costs. Replacing fish meal by 50% with bioflocs was only feasible when amino acids were supplemented, but ways to improve the nutritional value of bioflocs could be worthwhile. The results are especially relevant to farmers that produce seedstock and/or market-sized fish in closed aquaculture systems.

Technical Abstract: Biofloc technology is a microbially-based water quality strategy in which bacteria transform otherwise toxic ammonia and nitrite into nutritious biomass that may replace proteins in fish diets. Biofloc meal (BM) produced from an ex-situ bioreactor as part of a land-based integrated multi-trophic aquaculture system (LB-IMTA) was incorporated into five isonitrogenous diets consisting of, 1) fish meal (FM)-based control (no BM), 2) BM replacing FM at 25% (BM25), 3) BM25 with an amino acid (AA) mixture (methionine, lysine, leucine, threonine, and arginine), 4) BM replacing FM at 50% (BM50), and 5) BM50 with the AA mixture. These diets were fed to Red drum (Sciaenops ocellatus) advanced juveniles (initial weight of 61.5g) for eight weeks. Fish fed the BM25 diet had similar growth and feeding efficiency compared to the control, while those fed the BM25AA diet led to significantly faster growth and better feeding efficiency than the control. Fish fed the BM50 experienced negative growth values. While the BF50AA diet had numerically worse growth and feeding efficiency, these values were not significantly different than the control. Whole-body lipid content in fish fed the BM50 and BM50AA diets was significantly lower than the other treatments. Results demonstrate that BM, as a by-product from LB-IMTA, can replace FM without AA supplementation in the diets of advanced Red drum juveniles. Remarkably, replacing FM by 25% with BM when the AA mixture was included significantly improved Red drum growth compared to those fed the FM-based control diet. These findings demonstrate that BM with AA inclusions may not only improve production but potentially decrease feeding costs while enhancing sustainability in closed recirculating systems. Further research on enhancing the nutritional value of LB-IMTA produced BM may be a worthwhile direction to take advantage of a readily available by-product.