Understanding fish muscle growth regulation to optimize aquaculture production

Aquaculture has become an agronomic activity with noticeable development around the world to respond to the simultaneous decrease of fish captures and the increasing demand of aquatic products for human consumption. However, different problems limit the development of this industry and one of those is the time required for most of the cultured fish species to achieve economically viable the commercial size. The knowledge up to date of the regulatory systems involved in controlling growth has improved very much but, it is still necessary to devote efforts to transform the basic information in application to fish culture production. The aim of the present review is to summarize the knowledge acquired with the studies about the GH/IGF axis and other hormones regarding their function on the regulation of fish muscle development and growth. To this end, GH and IGFs effects in muscle cells on metabolism and development are examined, as well as the contribution of IGF-I binding proteins, IGF-I receptors and their downstream regulated molecules like TOR and its relation with cell proliferation and differentiation and the myogenic regulatory factors. The effect of regulatory molecules on cultured myocytes are reviewed as well as in vivo responses, including the model of sustained and maintained swimming. Key aspects we consider should be further investigated to complete the scenario of the regulation of fish muscle are also proposed.