Feed Conversion Efficiency (FCE)

Feed Conversion Efficiency (FCE) is the proportion of fed dry matter that becomes fish biomass, expressed as a percentage and calculated as weight gain divided by feed fed times 100; it is simply the reciprocal of FCR restated on a percentage scale, so an FCR of 1.25 equals an FCE of 80%. Modern aquafeeds and good husbandry achieve FCE values of 80–90% for salmon and 70–85% for warm-water species, meaning most of what is fed genuinely becomes saleable fish — a dramatic improvement from the 50–60% typical decades ago. The metric is useful in scientific and benchmarking contexts because it scales linearly: a five-point FCE gain is comparable across species, whereas the same gain expressed as FCR depends on the baseline. For the feed producer, FCE is the headline figure in diet validation trials, isolating feed quality from farm-management noise when diets are tested side-by-side in identical conditions. For the farmer, watching FCE (or FCR) trend lines week over week is an early-warning system: a sudden drop points to feed quality, oxygen stress, disease, or handling damage rather than fish appetite. FCE connects to FCR, specific growth rate, and protein ratio in every performance-review conversation.