Aquaculture system

In an aquaculture system comprising a water retaining aquaculture vessel with a bottom wall and side walls, means for aerating the water within said vessel, and means for removing particulate material from the bottom of said vessel, the improvement comprising the provision of a plurality of discrete foam substrate nitrification members with substantial surface contact area for substantially continuous circulation through said culture vessel, said discrete foam substrate members comprising:

• (a) a generally frothed, open-cell foam member having a density of between about 1.1 and 1.7 pounds per cubic foot, and fabricated from a matrix material having a specific gravity of between about 1.8 and 2.2 and with the surface area and bulk of said discrete foam nitrification substrate members having between about 25 and 100 cells per lineal inch dispersed therein;
• said system further comprising:
• (b) means for recirculation of water within said vessel;
• (c) means for introduction of oxygen into water within said vessel through said discrete foam substrate members and including means for separating water and waste product from said members while exposed to the ambient and filtration means for separating mature bacterial growth from said foam substrate members;
• and
• (d) air pump means within said vessel including conduit means having an inlet adjacent the said bottom walls of said vessel and an outlet adjacent the top of said vessel, a source of supply air entering said conduit means adjacent the inlet and arranged for discharge at the upper end thereof for substantially continuously receiving said discrete foam substrate members from said inlet and for upward passage through said conduit means and for discharge at the upper end thereof onto said filtration means.