Hi, I need some advice about some bottom feeders that will help keep the bottom of my tank clean. I currently have a 55 gallon grow out tank. I have 2 very messy eating oscars, 1 awanna, 1 clown knife, 1 asian needle, 3 yellow snails, 1 raphael cat, 1 black knife, a 5 inch pleco, 2 chidlids, a...