4. Summary
Taurine is a structurally simple nutrient, yet to which a myriad of complex roles are attributed. Some data on physiological and metabolic mechanisms explaining these roles is available in mammals, but they are particularly limited in fish, especially in broodstock and larvae. Nevertheless, an increasing number of species have been identified as having a clear, true requirement for dietary taurine. Deficiencies are characterized by depressed growth, low survival, increased susceptibility to diseases, as well as impaired development in larvae. Moreover, taurine deficiency may manifest itself through a green liver syndrome in some species. None of these effects are fully explained, although some initial hypotheses have emerged. However, as the state of knowledge of taurine physiology in fish remains fragmented and limited, additional research is evidently necessary to elucidate the mechanisms by which taurine exerts its actions
It is abundantly clear that as taurine-rich ingredients are removed from practical diet formulations, taurine supplementation will be required to optimize production in susceptible species. This will however require the registration of taurine as an approved ingredient for inclusion in fish feeds by the FDA, as the European Union and China have already done. Doing so will allow manufacturers to produce feeds in the United States with lower fishmeal content while promoting fish growth and health, thereby improving aquaculture environmental and economic sustainability.