i have six angels in my tank and they are all different sizes. i dont look at sizes when adding fish, as i think individual fish aggression plays a bigger role than physical size when talking about compatibility.
this is just me though, so you may want to wait for other replies.
sizing angels is weird to me, breeders give them all these different sizes...typical sizes are dime, quarter, medium, pre-breeder, breeder, but there are also pea, nickel, pre-dime, extra large, etc etc etc.
by those definitions I have 2 nickel sized, 2 quarter+ sized, 1 medium sized and 1 breeder sized angels and they havent killed each other yet
