Phytase supplemented diets do not reduce the abundance of cyanobacteria and common off-flavor compounds in hybrid striped bass (Morone chrysops x M. saxatilis) aquaculture ponds

ABSTRACT Freshwater fish grown in earthen ponds in the southeastern US can acquire “earthy” and “musty” taints due to the bioaccumulation of the cyanobacteria metabolites geosmin and 2-methyisoborneol (MIB) in the fish flesh and result in unmarketable fish. Dense cyanobacteria communities occur because nutrient inputs (phosphorus) are high in fish production ponds due to high feed application rates. In this study, hybrid striped bass (Morone chrysops x M. saxatilis) grown in earthen ponds was offered one of the six diets including diets supplemented with phytase to reduce phosphorus input to the pond and the subsequent intention of reducing the abundance of undesirable cyanobacteria. Water samples collected biweekly from each pond were analyzed for phytoplankton community structure and concentrations of geosmin and MIB. Differences in dietary phosphorus consumption among diets did not significantly affect soluble reactive phosphorus and total phosphorus concentrations, cyanobacteria abundance, and geosmin and MIB concentrations in pond water.