Either that's not a 55 or those fish aren't 17", but yea the general principle is the same...overcrowded. I went in a Chinese restaurant up north and they had a decent sized hex tank (65G maybe?) with 3-4 RD/Midas in it along with a huge silver aro...the fit was so tight that the aro just stayed in a circle with the head nearly touching the tail. Worst big fish/small tank I"ve ever seen.
