I would do as Subrosa suggested and test the parameters.......ph/hard?/soft? etc.....and find out what kinds of fish will do well in that water.
South American cichlids tend to prefer softer water with a lower PH.....african types tend toward the hard/high PH type water. Most fish are pretty forgiving and will adapt to whatever water you have as long as you properly acclimate and keep up with water changes.
I "highly" recommend the shelldweller species.....specifically the meleagris. I had a nice group of those in a 15gallon....they are FASCINATING ! The meleagris and the multifasciatus are a great choice for a 10gallon. The meleagris are less tolerant of each other, so fewer of those...but the multis are all just one big happy family and will breed themselves right out of the tank if you let them. Great source of a bit extra cash now and then if you have an lfs that will buy them from you.
Meleagris/stappersi/15gallon tank
multifasciatus/20long tank
