Dietary protein requirements of fish – a meta‐analysis

There are hundreds of fish reared in aquaculture, but nutrient requirements of the different species are still scarcely studied. Dietary protein is usually one of the first nutrients to be evaluated when considering the nutritional requirements of a novel species for aquaculture. Data on dietary protein requirement are already available for a large number of species, and this study aims to review the available data, enhancing eventual differences due to species, feeding habits, fish size, rearing temperature and water salinity. Overall, dietary protein requirements in the different studies ranged between 24 and 70% of the diet, depending on species and life stanzas. Dietary protein requirements were directly related to fish trophic level and water salinity, and inversely related to rearing temperature. Dietary protein intake was linearly related to weight gain, while protein retention was not affected, averaging 187 g protein kg−1 weight gain. On average, fish require a protein intake of 624 g kg−1 weight gain and dietary protein retention efficiency is close to 32%.