Quite a few options there really, depends on how small you want 'small' to be and what you want to spend etc, also what pattern you want, what you want to keep them with blah blah blah...
Hypans are good, stay smallish, king tigers, queen arabs....things like that
Pitbulls stay really small and are quite cheap for a fancy plec....
Alot of other things get big but they take a long time to grow so will stay smallish for a long time, nuggets, snowballs, goldies
and the smaller panaques are a nice size...if you can get your hands on them, everyone seems to have gone a bit nutty over those at the mo
All are pretty easy to keep its just the price that put a lot of people off
Hope that kinda helps