Hi Dave, I used to have a 125 gallon mixed south american chiclid tank.
A lot of these fish can be mixed, but make no mistake even a 55 gallon
tank is not that big to these fish. I read that you have gouramies with
your chiclids, unless there large gouramies they will eventually be
outgrown by your chiclids. Bala sharks are not an aggresive fish, they
may be bullied by larger fish.If you need any other advice or help you
can post here(I check stuff here about every week) or write me direct
under the subject matter "Tropical Fish"
Good Luck, Ed