There has been no evaluation of sulfur-based autotrophic denitrification using fluidized biofilters in arecirculating aquaculture system to mitigate nitrate-nitrogen loads. The objectives of this work were toquantify the particle size distribution, specific surface area, and fluidization velocities of three commer-cial sulfur products to provide a proof of concept assessment of the ability of sulfur particles to serve in afluidized denitrification reactor for nitrate removal from aquaculture effluent.