Over the years, I have had mixed success with them. I do have a.lot of fish and critters wrasses like to feed on. But this last one is only in the system for about 90 days. He is fat and eating anything I offer him. He is almost 3" long, so he is a big one, capable of eating pretty big bits of food. He also cleans the fish, but I don't think there are enough parasites in a closed system to get keep them alive that way...and who would want their fish covered in bugs so a cleaner wrasse could stay fat! I will claim success if he lives 5 years or more. But for now, he is fat and eating well. He likes frozen brine, but I mostly feed him and the others my own concoction. I would say he is like keeping a Mandarin, if you get a big fat one that isn't finicky, you can probably keep him long term.