I have a pair of angels in a 20 gallon tall aquarium (just angels no other fish). They are a few months old and about half full grown. This weekend I purchased a Pictish catfish figuring a bottom dweller would be nice for interest sake and add some variety to the tank. Seeing the catfish I was impressed with him compared to some of the other less interesting bottom dwellers. I figured he would stick to the bottom of the tank and the angels would have the rest to themselves. I am aware of how large both the angelfish and catfish get but am not concerned about biolode since I enjoy tank maintenance and do frequent water changes. Now that the catfish is in with the angels I realize how much more active he is than they are and am a little concerned with how the angels will react. He usually sticks to the bottom but does frequently scoot up the sides of the tank. The angels don't seem to be too irritated yet but I am aware that they are already in a tank that is on the small side for when they are fully grown, will the catfish stress them out? Neither are a concern eating eachother since they are of similar size.