In my opinon, having had many pairs of angels, for juveniles a 29gal would be minimum, but 40 or 55 would be great! My angels got very large in my 55gal. Many fish are good tankmates, usually more placid species are better and I have read many reports that adults will eat tetras or any fish small enough to get in their mouth. I kept mine w/cherry barbs, blue rams, albino pleco and african feather fin catfish. Good luck.