As the aquaculture industry grows, so does the need for affordable protein in fish feed. At Lincoln University of Missouri (LU), researchers are studying whether soybean meal offers a practical way to reduce reliance on fish meal. The research examines whether soybean meal can replace a portion of the fish meal used in aquaculture feed. Fish meal, a protein-rich ingredient traditionally made from wild-caught fish, has long served as a primary protein source in fish diets. However, limited supplies and high costs have prompted researchers to evaluate alternative ingredients such as soybean meal, which offers high protein content and digestibility, a favorable amino acid profile, wide availability and lower market cost.
“Feed accounts for the highest operational cost in aquaculture — often 50% to 70% of total production costs,” said Moureen Matuha, who leads fish nutrition research in LU’s Aquaculture Program. “Using soybean meal as an alternative protein source in aquafeed could lower production costs for fish producers while creating new demand opportunities for soybean growers.”
LU first evaluated soybean-based diets with or without taurine supplementation under controlled conditions at its Aquaculture Research Facility. Promising growth performance of juvenile largemouth bass in this initial study supported further testing of the diets under real-world farm conditions.
“The goal is to develop practical, science-based solutions for aquaculture producers while also supporting local soybean farmers,” Matuha said. “What makes our work different is that we are not only working in the lab. We are also validating our findings on farms to ensure they are practical for producers.”
LU researchers are now conducting a six-month feeding trial at NuTerra Farms in Dexter, Missouri. The trial began in April and will continue through October. The study compares three diets: a standard commercial feed and two experimental diets that replace 30% or 60% of the fish meal with soybean meal. The trial is part of the project “Optimizing Soy Inclusion in Largemouth Bass Feeds: Balancing Fish Performance, Economic Viability and Environmental Impact.”
This research is supported, in part, by the Soy Aquaculture Alliance and the Missouri Soybean Merchandising Council through Missouri soybean farmers’ checkoff investments, which fund research into new uses and markets for soybeans. The NuTerra Farms trial allows the LU team to evaluate how the soy-based diets perform in largemouth bass under commercial production conditions. Howard Magill, who operates NuTerra Farms with his family, said the partnership came at the right time. His family had begun preparing ponds for largemouth bass when LU started searching for a producer willing to host the long-term study.
“There’s been concern in the industry about soy-based feed affecting water quality and fish health, so we wanted to be part of something that could either confirm or clear that up,” Magill said.
At roughly the halfway point of the trial, measurements indicate that fish fed the 30% soybean meal replacement diet have experienced the strongest growth so far. The standard commercial feed group ranks next, followed by the 60% replacement group. Matuha emphasized that the trial remains in progress and the early pattern may change as the fish continue growing. The research team plans another round of measurements in August before completing the study in October. The on-farm trial also reflects common challenges aquaculture producers face during a growing season, including weather-related feeding disruptions and an aerator failure that affected dissolved oxygen levels in one pond.
Researchers continue monitoring fish growth, feeding response and water quality throughout the trial. Beyond growth performance, the LU team also wants to understand how soybean-based diets affect fish health and product quality. Researchers plan to evaluate nutrient composition and conduct sensory analysis to assess taste, texture, aroma and overall appeal.
“You cannot introduce a novel fish feed ingredient without understanding its impact on the final product for consumers,” Matuha said. “We are evaluating whether soybean-based diets affect the sensory profile and nutrient composition of largemouth bass.”
The research also points to a broader opportunity for Missouri soybean growers. Most soybean meal used in the United States currently goes to poultry, swine and cattle, while aquaculture represents a smaller but growing market. Increased domestic aquaculture production could create additional demand for alternative protein ingredients. Matt Amick, director of market development for the Missouri Soybean Merchandising Council, said practical research plays an important role in developing that market.
“Moving more aquaculture production within our borders and inland to the Midwest presents diversification opportunities for farmers, new markets for soybean farmers to use soybean meal in aquafeed and better food security for consumers,” Amick said. “While the market for soy in aquaculture is relatively small at this point, on-farm, practical research such as the partnership between the Missouri Soybean Merchandising Council, Soy Aquaculture Alliance, Lincoln University and NuTerra Farms is vital to expanding awareness and growth for fish and soybean farmers.”
In addition to the NuTerra Farms trial, LU continues related studies involving largemouth bass and rainbow trout at different stages of development. Together, these projects provide a broader understanding of how soy-based products perform across species, production settings and growth stages.
