Is dietary taurine supplementation beneficial for farmed fish and shrimp? a comprehensive review

Taurine is a neutral β-amino acid derived from the metabolism of sulphur-containing amino acids. It is present in high concentrations in animal tissues, especially heart, retina, skeletal muscle, brain, large intestines, plasma, blood cells and leucocytes. Therefore, this amino acid plays significant roles in many physiological functions, including membrane stabilization, antioxidation, detoxification, modulation of immune response, calcium transport, myocardial contractility, retina development, bile acid metabolism, osmotic regulation and endocrine functions. Historically, taurine has not been considered as an essential nutrient for fish. However, recent studies have indicated that taurine synthesis widely differs between fish species and demonstrated that it plays a key role in aquaculture and nutrition of freshwater and marine fish and shrimp. Animal proteins are rich in taurine, whereas plant proteins are taurine-deficient. Therefore, fish fed plant protein-based food may require exogenous taurine for maintaining their physiological functions. Nevertheless, taurine may be conditionally indispensable for fish and shrimp, depending on dietary protein source, fish species and size, feeding habits, previous histories and the rate of metabolism of its precursors, namely cysteine and methionine. It is my belief that taurine functions in, and benefits for, farmed fish and shrimp are now more than worthy of critical review and analysis. This review summarizes the current knowledge on the roles of taurine in fish, particularly farmed fish and shrimp, with emphasis on taurine structure and biosynthesis, physiological functions, the effects of dietary taurine on fish performance and health and live food enrichment with taurine.