You could try to get some of shrimp since they are some of the larger ones once they get to adult size. I have a otto's now and have had more of them and I noticed they like to eat the scum not really the algae (at least thats what mine have done and do). Maybe if you can find a flag fish? I have a American/Florida flag fish (female) and she eat s algae like crazy,... everykind!!!!! She is always eating, seriously always eating and always pooping LOL. (Don't tell her I said that she would be embrassed.......)
