Mixed culture is fine. Scavengers are different from other fish. Lucky fish with thick skin can't hurt it. However, it should be noted that your sweeper was caught from outside and may carry some germs. It is best to disinfect it separately and then put it back together with the lucky fish for polyculture (take a bucket and put some disinfectants, such as potassium permanganate and sea salt, or go to the aquarium to buy the corresponding disinfectants).