A couple tiger barbs maybe but better to keep In larger groups that would require a larger tank. Some shell dweller cichlids may work if you can fin them in your area I'm not very versed with them so can't give you specifics. You could do a single of a smaller mbuna species, but yet again there better in groups and larger tanks.
I got it dwarf puffer aggresive and tiny put snails in there and he'll go nuts.