Aquaculture industry has witnessed a tremendous growth globally in the last 50 years having a production of over 50 million tons in the present times. Consequently, this growth has environmental impacts as well. Aquaculture wastes contain nitrogenous compounds (ammonia, nitrite, and nitrate) as result of uneaten fish feed, fish respiration and excretion. However, these nitrogenous substances are necessary for the growth of aquatic plants, bacteria, and algae. An excessive concentration of these nutrients results in eutrophication. Thus, it is necessary to remove the ammonia and nitrate wastes from aquaculture streams. The goal of this research is to use a low-cost adsorbent to treat aquaculture nitrogenous wastes. Pine bark biochar is doped with a nitrogen containing precursor to alter the surface chemistry. The modified adsorbent is characterized in detail. The obtained properties of the adsorbent are used to design a continuous fixed-bed adsorption column to remove ammonia and nitrate from model aquacultural streams.