The present invention relates to a floating media moving bed portable biofilter and degasser and methods of using same useful for the biological treatment of aqueous nitrogenous waste. Provided herein are enhanced biofilter systems and methods for removing nitrogenous wastes from bodies of water. The portable biofilters described herein remedy the deficiencies of existing biofilters described above due to their enhanced nitrogen removing efficiency coupled with their simple and robust design, relative inexpensiveness, portability, ease of cleaning and maintenance, minimized trapping of aqueous solids, minimization of off-flavors in aquacultured fish, and immediate functionality when transferred to different sources of water. These advantages render the portable biofilters of the present invention suitable for commercial applications for aqueous nitrogenous waste removal.