Fish as Food or Feed? Aligning FIFO with LCA and Food System Objectives

Aquatic animals contain essential and unique nutrients for human health. They are produced from a continuum, rather than a dichotomy, of aquaculture and fisheries, from which, it is crucial to maximize nutrient availability for human populations. Marine ingredients (primarily fishmeal and fish oil) have been a critical part of carnivorous fish diets, for fish performance, and delivering omega-3 fatty acids to consumers, but have received considerable criticism over their sustainability. Metrics such as the Forage Fish Dependency Ratio (FFDR) and Fish In: Fish Out (FIFO) ratios have been proposed to assess the efficiency of “fish as feed”, yet to-date these approaches have overlooked nutrient retention from reduction fishery resources into final aquaculture products. They also failed to capture broader food system dynamics, including market demand for fishery resources, multi-functionality of the co-products, and the growing contribution of fish by-products to marine ingredient supply. Furthermore, FFDR and early versions of FIFO were not compatible with Life Cycle Assessment (LCA) methodology, limiting comprehensive sustainability assessments that include LCA metrics such as Global Warming Potential. Introduction of economic allocation into FIFOs addressed these challenges of compatibility with LCA but did not address nutrient retention. The “eFIFO” approach was extended to the economic nutrient FIFO (neFIFO), providing an accessible metric for comparing and improving marine nutrient retention in aquaculture. Nevertheless, improved nutrient availability alone does not guarantee affordability or accessibility, underscoring the need for nutrition-sensitive strategies that ensure equitable access to key nutrients without compromising environmental resources. Additionally, effective fishery management must extend beyond stock status alone to include ecosystem‑level assessments and consideration of broader impacts on wildlife. This paper synthesizes existing literature on marine ingredient sourcing and use in aquaculture, with a particular focus on fish conversion efficiencies and nutrient retention. The work also compared different methodologies for assessing “fish as feed” dependency and efficiency, and included case studies examining the use of marine ingredients across aquaculture species and feeding strategies. An access link to the FIFO Performance Tool is provided, allowing stakeholders to calculate and optimize FIFO metrics in line with industry standards and Product Environmental Footprint Category Rules (PEFCR) compliant LCAs, and to integrate these outputs into broader sustainability assessments and reporting frameworks.