Strawberry conchs (or any small conch) would be good. i have 1 in each 20gal for years and they're happy and keep sandbed turned.
I do agree with others, you already have two damsels (clowns) in a 25g, any other fish (for low maintenance) should be veeeery docile and habitat restricted (think clown gobies with their fav perching spots, maybe small shrimp goby combo?)
I actually have 1 conch in there - and he does alright, but my tank is in direct sunlight - so it creates more algae than most - Maybe the solution is add another conch?
Maybe you're right about the Goby... I wouldnt mind a perching goby.
