55g tank discussion
My list of schooling fish under 3".
Any fish 2" or larger should be angel safe. My favourites would be Dwarf neon rainbows, Cherry barbs, Serpae tetras, Marbled Hatchets, Harlequin Rasboras, Bleeding heart tetras, Congo tetras, Panda Corys and Black phantom tetras.
So... A general rule of thumb that (if used in conjunction with fish species requirements like min tank size, compatibility etc...) is 1" of adult fish per gallon. 2 angels, 12", and a small school of 6 2" fish is 12". Have fun!