Richard Newton has recently been working with the Marine Ingredients Organisation (IFFO, https://www.iffo.net/) to revisit Fish In: Fish Out ratios (FIFOs). FIFOs have often been used by NGOs and certifiers as a measure of how efficiently marine resources are utilised in aquafeeds. Richard explains here, why the current methodology needs some revision, following his recent appearance at IFFO’s 59th annual conference to present his findings.