You will still need to vaccum your tank to get rid of fish poo but some fish to help keep the bottom clean of extra food would be cory cats and loaches.
theres no fish taht cleans the sand..
if cory eats the things off the sand he'll poop on the sand, endless cycle, you jsut gotta stick your hand in and vacuum
i figured there was no fish that cleaned the sand i was thing about cory cats. my cat now just hides and comes out at night (Synodontis Ocellifer Catfish)