Yup otos are supposed to be great algae eaters & only grow to be 1 1/2" (approx.). But they do need to be kept in groups (the bigger the better), + I hear they can be pretty dang sensitive to water quality, & are prone to dying for no apparent reason....If I were you, I'd get a nice apple snail - they're good cleaners (I actually have to drop zucchini into my 15gal to feed my 1 snail coz my tank's so clean), & apple snails can't reproduce by themselves like many other breeds can. Sure, they're not the prettiest picture when they're suckered to the glass but then again, I don't think anything would be lol. Snails are really hardy too, I even use salt in my tank & he's still chugging away happily. Only thing to watch is that they like to escape so make sure ur tank's well covered if u do get one.