Quillaja saponins—a natural growth promoter for fish

Environmental concerns and the forthcoming ban on antibiotics in the European Union have renewed interest in renewable and non-persistent plant-based growth promoters in fish feeds. A review of the published literature and unpublished recent results following addition of a Quillaja saponin mixture in the diets of common carp and Nile tilapia are presented. It emerges that Quillaja saponins have the potential to increase growth in culture fish species, reduce their metabolic rate and suppress reproduction in tilapia. The current study is the first to have demonstrated beneficial effects of a Quillaja saponin-rich fraction when used as a feed additive in fish diet. It is hoped that this collation of information and synthesis of results, discussion and conclusions will act as a catalyst for future research on isolation of the active fraction, its optimum concentration for obtaining the desired effects, and physiological mechanisms of action for the diverse biological effects of these compounds.