If i took new fish into this tank , i usually put over some old fishes.Gourgous Collection, but if your adding more it is definently time to upgrade. Those guys barely have anywhere to move.
At so they can swim without problems with this decor, and if they couldn't i will put some fishes over? fishes but not decor, cose if i put over decor my tank will looks like millions of another tanks.I agree with anubisscott. Atleast pull out most of the decor in the tank, that way they can swim around a bit without bumping into other fish