Just want to address one other thing....
I noticed in your second post you made referrence to having oscars...meaning more than one!!!
Please be aware that even a 55 is to small for more than one adult oscar.
IMO oscars should not be housed in any tank that is not at least 18" wide (front to back). Even a 70 thru 110 gallon tank is only adequate for a pair of oscars.
Please remember, oscars can get up to 16" and a tank that is only 13" wide is really not good.
Please do yourself and more importantly, do your fish a favor and get a larger tank.