I keep emerald rasboras, CPDs, dwarf cories, ember tetras, RCS, and guppies with my four. But I have them all in a 60 gallon tank. They all get along fine. Maybe you can do a scaled down quantity of one of those types.
I have these castle pieces for sale
$14 a piece or both for $25. I would prefer a local pick up. Actual shipping at buyers expense.
Lol... I posted these up a couple of years ago.... Had no takers... Been sitting on a shelf ever since. Decided to try again