i have had a sixline for 4 years. have 2 different urchins tux and longspine, turbo snails, cerith snails ect..... had a ^^^^^ cleaner shrimp for 3 years, at worst you will get an aggressive one that will bully other fish. only fish my sixline ever bothered was my mandarin right after introduction because of similar color and size im assuming. But i have heard of some nasty wrasses. worst case senerio with mine is that he will eat live pods and bristleworms, because thats the majority of their diet. so nothing bad