Nutrition, hormones and growth.

A review is presented relating to the effects of hormones on food intake and nutritional state and also of the effects of food intake and nutritional state on hormone activity. These interactions and their effect on fish growth are described.Growth hormone, thyroid hormones, insulin, and gonadal steroids have all been implicated in the normal growth processes of fish and their metabolic actions have been related to the nutritional state of the animal. Furthermore, variations in plasma levels and hormone application appear to affect food intake and food conversion.Anabolic steroids and their possible involvement in aquaculture practice has been an area of active investigation for the past few years. The current situation is reviewed, particularly regarding relevance to protein intake.