The negative impact of HORM-containing diets on fish growth observed by Hixson et al. (2014b), may have been due to antinutrients present in the meal. Antinutrients, or antinutritional factors (ANF) are compounds that serve a metabolic or protective function in the plant,but impair the nutritive value of animal feeds (Francis et al., 2001; Bennett and Wallsgrove, 1994)