Originally Posted by
Mermaid_dreamR
http:///forum/post/3222192
Never mind, I found the answer on http://www.aquariumpros.com/articles/badfishlist.shtml and sadly, that answer was "NO"
That's not true actually. Not necessarily ideal, but there are some octopus species that have proven to be quite capable of coexisting in a large enough tank with other fish and inverts. I have done it myself or I wouldn't suggest it.
You specifically want to aim for Abdopus aculeatus. It is the most commonly imported Indonesian/Pacific species. They don't grow very large, will do fine in a 50 gallon. I will not back this advice with any other species, and I would suggest adding the octopus last.
I kept mine with a yellow coris wrasse and a rabbitfish and several peppermint shrimp that never disappeared. Occasionally the octopus would squabble over food with the fish, actually wrestle it away from them. They won't harm corals in general, but they like to rearrange anything they can lift so anything valuable needs to be glued down well. Their skin is pretty sensitive, so I wouldn't suggest housing with anemone's or stingy corals.
Other things to take into consideration of course are, how likely are the fish in your reef to harass the octopus? No Damsels or other aggressive/seriously territorial fish. Octopuses are top-notch predators, but they are not invincible.
One last thing to consider is the fact that you want to seal the tank. This may not be practical for your reef, depending on your maintenance routine, heat problems, etc.
Now, all those things considered, have fun and good luck if you should decide to attempt it. (They are very much worth the effort when you get a young, healthy one and keep them in a properly setup tank)