I have a mated pair of maroons. Its part of the symbiotic relationship for the nems. They provide the slime coat and protection for the fish and the fish make sure it has food and a clean environment to survive. Sometimes mine will clean in front of it and then clean paths to where it thinks it might go. When I first put it in, they kept the entire area clean for a foot in front of it. It finally settled where it wanted to be and now they will clean around it in all areas, but pretty much leave the rest of the tank alone. They will pick up snails, rocks and other things and move them around, but I look at this as boredom more than anything. I think its funny when they pick up one piece of sand, swim away and spit it out. Like that's really going to help anything.