I have had a zebra moray for many years, and kept it with smaller fish like clowns and a royal gramma. The ONLY time it ever hurt a fish was when it and a trigger grabbed the same piece of shrimp - the eel accidentally clamped down on the trigger's head (it survived this, though).
If you want a definitely fish-safe eel, get a zebra moray. Mine is between 3.5 and 4 feet long (got it at 20 inches or so) but it sounds like your tank is big enough.
I doubt if an anemone would make any difference to an eel ready to eat a fish... Personally, I think a well fed snowflake (especially if you start out with a smaller one) is a safe bet... However, my experience has been that the two snowflakes I've owned both "walked" out of covered tanks and died. I kept the zebra moray in an uncovered tank for many years and it never wandered. (It's in a well-covered 210 now.)