Booker, I had a list of suggestions, but as I started to post I noticed Jeffuth's stock list on his post. Research jeffuth' s listed tetra and catfish species as well as Bolivian rams. Of course if you decide to stock like jeffuth, you'll have to cut the size of the schools down to match your tank size. Note: forget the red tail shark a 55 gal
is too small. A few giant Danios would work. Nice grouping of fish jeffuth.