I just got a 180 gallon tank and am stocking with a bunch of african cichlids. I am concerned about oxygen concentration in the water. In the past I have never used anything like air stones or power heads to oxygenate my tank but I havent worried about it because I've always used hang on back filters which I felt broke up the surface area enough to provide adequate oxygen. My new large tank has a canister filter so the surface area doesnt get broken up anymore. My question is: do I need to employ any sort of artificial oxygenation for my tank for my africans or are they fine? I have seen many photos of tanks that look like they dont have any such equipment but I've also seen some with bubble walls and things. Don't know what to do. Thanks.