I think I may be a special case but I have an 0.Briareus in a 125 gallon tank that lives with a blue tang, a yellow tang, a mimic tang, a mated pair of clown fish, 2 chromis, a checkered puffer, a flame hawk, a rock beauty angel, and two anemones. after a few months so far only one casualties, a gobie tried to steal her den and she took care of him, other than that everyone leaves the octo alone. However. from what I have read it usually doesn't work out that well. the difference may be that I raised my octo from a VERY young age, I caught her when she was only days old, just a clear blob with blue eyes.