So I bought 3 more pristella tetra's to give my albino one some friends...and he doesn't really interact with them. Is this normal? He won't school with them but will school with the glo tetra or the candycane tetra I have. Also, can you mix the normal pristella tetra with the gold pristella tetra? Or does each have to have 6? They look the same and I was told they are the same species, but is this true?