Creatine in Sustainable Fish Aquaculture

Creatine is a popular ergogenic sport supplement used to improve exercise performance and muscle growth in athletes. Further, studies suggest protective effects of creatine in neurodegenerative diseases, type 2 diabetes, osteoarthritis, fibromyalgia, aging and fatty liver disease in humans. Similarly, the versatility of creatine, as a supplement or feed additive, has been evaluated in different animal production systems, including terrestrial livestock, poultry and aquaculture fish species. Some of the observed effects are increased antioxidant activity and flesh quality, improved lipid homeostasis as well as enhanced overall productive performance. Despite creatine being synthesized endogenously, this capacity might be insufficient to adequately cover the creatine needs in fish fed diets formulated with ingredients devoid of this nutrient, notably plant protein feedstuffs. As aquaculture industry moves toward sustainability, removal of creatine-rich dietary ingredients, such as fishmeal, in aquafeeds will likely further increase in coming decades. Thus, under this scenario it might be necessary for dietary supplementation of creatine to support optimal fish productive performance and product quality. This review describes the current knowledge of creatine physiology and metabolism in fish, and highlights possible parallels with metabolism in livestock species, mammalian models and human as well as the benefits obtained from creatine supplementation.