Updated July 17, 2025:
Summary
The economic impact of the US catfish industry is significant due to its success in the southern states of Alabama, Arkansas, and Mississippi, which have become the nation’s most prominent aquaculture region. However, the catfish industry has faced numerous setbacks and challenges throughout its history. One of the most persistent challenges is the farmers’ demand for low-cost feed, which often results in the use of low-quality ingredients in catfish diets. While this pressure has stimulated extensive nutrition work to improve feed formulations for channel catfish and the initiation of work with hybrid catfish, it has also driven the industry toward using the least costly feed ingredients. Presently, catfish feeds are some of the most cost-effective in the industry. Typically, these feeds are based on a low level of animal by-product proteins (such as meat and bone meal), a moderate level of solvent-extracted soybean meal, and plant-based by-products (such as distillers’ by-products) as the primary protein source. These formulations may marginalize health and production in order to achieve lower-cost feeds. Soybean meal has been and will continue to be a key component of the protein in these diets. However, with the advent of new genetic lines and processing technologies, the use of newer soy protein may improve the nutrition of the fish and warrant evaluation. Towards this goal, the project evaluated the replacement of typical solvent-extracted soybean meal in a basal diet (Basal) with an enzyme-treated soybean meal (Basal-ET), a low oligosaccharide soybean meal (Basal-LO), and the comixing of soybean meal with a corn fermented protein (Basal-CFP). These diets were then tested in fingerling channel catfish under laboratory conditions and in in-pond-raceway systems (IPRS) to evaluate the efficacy of the modified diets. Results from the indoor aquaria trail with fingerling catfish, and IPRS results rearing fingerlings to advanced stockers and then to commercial size fish both demonstrated desirable growth and feed conversion of these fish. There were no adverse effects of any of the protein combinations across the trials. In general, the use of low-oligosaccharide soybean meal or the use of CFP as a complimentary protein resulted in the best response of the fish to the tested diets.
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Discussion
Hybrid catfish account for more than 50% of catfish production in the US, yet there is limited nutritional information on practical feed formulations. Catfish, as a species, accept a wide range of feed ingredients and have well-documented nutrient requirements, allowing for low-cost feed formulations typically containing 32 to 36% protein. Solvent extracted soybean meal (SBM) is a well-known plant protein ingredient commonly used in catfish diets due to its favorable amino acid profile, nutrient composition, and availability. Nevertheless, some thermostable anti-nutrient factors (ANF’s) in SE-SBM such as oligosaccharides and phytate could negatively affect fish health. Advancements in processing technology and genetic selection have led to improved soy-based ingredient options. On the processing side, enzyme treated SBM (ET-SBM) is the result of dehulled and defatted SBM passed through a thermal process and later treated with a conjunction of enzymes (e.g. non-starch polysaccharide enzymes etc.), which ultimately reduces oligosaccharides and antigens. In terms of breeding and seed selection, commercialization of low oligosaccharide strains of soybean has translated into low oligosaccharide SBM (LO-SBM) accomplishing reduction in stachyose and raffinose, while raising protein content.
Another strategy to improve feed formulations is the use of complimentary ingredients in the formulation. Corn fermented protein (CFP) is, likewise, a promising ingredient for catfish feeds, as it is easily produced by way of fermentation using ethanol and yeast, producing an ingredient with higher protein concentration and phosphorus digestibility, with a positive amino acid profile. The forementioned ingredients have been widely utilized in feed studies on broilers, weaning pigs, several species of fish, and shrimp. Most of these trials report no negative effects on growth performance during these trials. However, ET-SBM, LO-SBM, and CFP have not been nutritionally examined for hybrid catfish. Hence, our primary objective was providing comparative results of the use of ET-SBM, LO-SBM, and CFP in hybrid catfish feed formulations under pond culture conditions.
Under our culture conditions, no statistical differences were seen for most growth parameters among dietary treatments during juvenile and grow-out phases for the hybrid catfish reared in a clear water aquaria system or in pond based IPRS trials. These results are similar to that of a parallel study ran under the same condition with juvenile channel catfish (Ictalurus furcatus) (Paladines-Parrales et al., 2025) were no significant differences were seen among similar dietary treatments. Nevertheless, hybrids outperformed in FCR, survival, and weight gain (%) when compared to the results of channel catfish, a well-known characteristic of hybrids. Still, under our aquaria and pond-based culture conditions, the replacement of SE-SBM with the other ingredients seemed to lead to better performance than the basal diet.
While there is little nutritional research with hybrid catfish, there are studies with other species, particularly in clear-water controlled systems or RAS. Paladines-Parrales et al. (2025) used an equivalent set of diets for juvenile channel catfish, finding that diets containing CFP or LO-SBM produced better results than the commercial reference diet and that the LO-SBM based diet outperformed the basal and enzyme treated diets. Romano et al. (2021) found no differences in growth when SE-SBM was replaced with ET-SBM in rainbow trout diets in flow through system, whereas Xuquan et al. (2022) reported an increase in final biomass and lower FCR when enzyme-hydrolyzed SBM was used as replacement of fish and poultry meal in juvenile channel catfish in cage-pond culture, indicating this may be a better protein source. Yamamoto et al. (2024) reported similar results for replacement of SBM with 25% CFP in juvenile catfish reared in RAS. Oladipupo et al. (2024) also found no differences with 50 and 100% inclusion of ET-SBM or LO-SBM replaced SE-SBM in California Yellow Tail reared in RAS. However, Kumar et al. (2020) found better performance in rainbow trout when using 16 % ET-SBM replacement vs SE-SBM. Li et al. (2020) also found improvement in growth with ET-SBM when used in juvenile largemouth bass diets. These results indicate that, although ET-SBM and LO-SBM are an improved meals, species which are more sensitive to soy based antinutrients will have a better response than species that are more tolerant.
With regards to proximate composition and nutrient deposition for our research, there were few shifts in nutrient profiles indicating well balanced diets. However, there was an increase in moisture content in fish fed Basal-CFP compared to Basal. Also, a higher level of fat was found in the grown-out fish compared to juveniles, which agrees with most reports which indicate the fat content tends to increase as fish become older. Corresponding to shifts in proximate composition for fish reared in the RAS system, IPF values were significantly higher in fish offered the Basal-ET diet. There were no differences in IPF or HIS in the other trials for which this was measured.
Based on limited changes in growth, feed conversion and proximate composition, one would expect few changes in ANPR values. Protein retention in fish offered the Basal-LO diet was superior to that of fish reared on the basal diet, again indicating an improvement in nutrient availability. Although not significantly different, fish offered the Basal-LO diet had ANPR values numerically better than fish reared on the other diets.
Conclusions
As there were limited differences in growth, survival, and nutrient retention, one can conclude that all of the tested diets were suitable for commercial evaluation. However, the cumulative data to date indicates that there is an improvement in traditional SBM as it is further processed and/or blended with CFP. While we did not see significant differences across the board, fish fed the basal-LO and basal-CFP diets appeared to have consistently better growth, higher levels of protein retention, and higher protein percentage within whole body analysis across the trials. Even though findings are not always significant, the cumulative data indicates that practical diets designed for catfish can be improved.