I have some mysery snails purchased to help with the clean up in my 30 gal tank. Can they co-exist with the clowns? The smaller of the two loaches I have is currently rsting on a rock eyeballling the snail. He has tried to nibble on this one a few times - the snail, fortunately, has it's trapdoor closed tight. I have not seen the larger of the two clowns messing with any of the snails.