I have a blue liped trigger, a diamond back gobby, a damsel,a spiny-box puffer, and a large pistol shrimp in my tank. This is not the norm though. I hand feed all the fish except the pistol and damsel. And the octo gets 1 large crayfish every week. So I think the reason they all get along is because they are always well fed. But like I said, this is reare.
Although it does occasionally work out, and I mean nothing against anyone wo has used it, fish and cephs are not ususally a good match. However, macroalgae and echinoderms are good tankmates, and some people keep corals with them. Don't be surprised if the octo decides to 'reposition' these creatures. Also make sure the corals do not sting or release toxins.