WWW.WAS.ORG • WORLD AQUACULTURE • MARCH 2025 21 (CONTINUED ON PAGE 22) USAS CHAPTER ARTICLE: Navigating the Currents of Change in U.S. Catfish Nutrition Research Fernando Y. Yamamoto and David J. Wise The catfish industry is the largest producer of food fish in the U.S., reaching ~170 thousand tons in 2023 and generating $443 million in sales (USDA, 2024). This accounts for over 58% of gross food fish sales in the nation, with an economic impact of ~$1.9 billion when including variables for sales and expenditures (Hegde et al., 2021). In catfish farming, feed represents the main production cost, and the efficient use of this resource is critical for farm profitability. Over the past 2 decades, the US catfish industry has changed its production practices to overcome the challenges imposed by the economic recessions (2008 and 2012), bacterial outbreaks, and competition with other fish products. The adoption of new technologies such as intensively aerated ponds, the attenuated Edwardsiella ictaluri vaccine and its delivery method, as well as the production of the channel and blue catfish hybrid on an industrial scale, enabled the intensification of the earthen pond systems and increased farm productivity (Hegde et al., 2022). Despite the now widespread production of hybrid catfish, the available feed formulations still rely on requirements originally established for the channel catfish (Ictalurus punctatus). The history of channel catfish nutrition research in the United States has been well documented in a literature review from Drs. Ed Robinson and Menghe Li (2020), both former faculty of the Thad Cochran National Warmwater Aquaculture Center. Their review highlighted the key scientists, research focus areas, and geographic distribution over the decades. Yet, tracing back some of the scientific publications on Ictalurus sp. nutrition from U.S. institutions over the past 25 years, limited research articles have been published with hybrids when compared to channels (Figure 1). Hybrid Catfish The hybrid catfish can be obtained by artificially inducing the spawning between the female channel catfish (Ictalurus punctatus) and the male blue catfish (Ictalurus furcatus). For the past 10 years, hybrids have been the predominant catfish farmed in the US, mainly in the state of Mississippi (Hegde et al., 2022). When compared to channel catfish, hybrids have demonstrated higher disease resistance, faster growth rate, greater fillet yield and increased harvestability. As previously mentioned, despite being the preferred farmed Ictalurid, only a handful of nutritional studies using hybrids can be found in the literature. This can be credited to the poor production performance of this fish observed in aquaria studies (Yamamoto et al., 2024a), a trait likely inherited from the blue catfish, which has consistently shown high feed conversion ratios (FCR) in these conditions (Webster et al., 1992, 1995a; 1995b). In glass aquaria, the hybrid catfish are skittish when exposed to human interaction, and they usually cower in the back of the tanks. If we take a closer look at the scientific literature surveyed, we will see that most of the nutritional studies using hybrids were conducted in experimental ponds (Figure 2). In our laboratory, several attempts were made to fix this issue, and the best approach developed was to cover the front of the aquaria (and sides for the tanks at the edges) with peel-and-stick paper and monitor feeding activity through the bottom of the glass tanks. Under intensive pond production, a significant drawback for this hybrid is their size disparity (Figure 3), as unevenly sized fish can complicate the filleting process, ultimately leading to monetary penalties from processing plants to the catfish farmers (Wiese et al., 2006). In nature, the blue catfish has been considered an apex predator by some ecologists, presenting a preference for consuming animals FIGURE 1. Frequency of articles on catfish nutrition studies conducted in the US and published in peer-reviewed journals for the past 25 years. There were 139 articles found within this timeframe, and frequency data was distributed per year with the different animal models. FIGURE 2. Number of catfish nutrition studies conducted in the US published in peer-reviewed journals. The articles surveyed are presented in different experimental conditions and animal models.
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