Feed is the most expensive component of U.S. catfish production, contributing over 40% of total production costs. It is well established that improving feed conversion ratio (FCR) at a given level of production improves profit. FCR is also a primary sustainability metric, given the embodied resources in fish feed. Thus, FCR is a key measure of production efficiency and environmental performance. The simplicity and importance of FCR makes it an attractive metric for certification programs, apparently based on the assumption that "good" farmers obtain lower (better) FCRs, and that "bad" farmers can and should improve practices to lower their high FCRs. The reality is far from this assumption. This review focuses on the case of U.S. commercial catfish production and challenges the question of whether FCR is an appropriate certification metric that will accurately reflect better management of pond aquaculture. Although farmers understand the economic importance of FCR, control over production processes is limited for catfish production in open ponds. Major factors affecting catfish FCR include the type of fish (catfish/hybrid catfish), type of feed used, feeding practices, disease, production systems, economic factors, marketing strategies, and climatic conditions. In addition, regulatory stringency of environmental and food safety laws limits producer’s ability to control fish losses to piscivorous birds and bacterial diseases. There is a wide disparity in FCR obtained from research studies and commercial conditions. Thus, certification standards stipulated from research studies will not reflect on-the-ground realities of farms. If ponds managed according to the protocol of the university research verification program cannot routinely achieve FCRs of 2.0 or less (Table 1), it is unrealistic to expect farmers to do so. In summary, for U.S. catfish production, FCR is not a reliable, consistent metric that reflects management ability, and thus it is not suitable as a blanket certification standard.