We keep Southern Conger eels in our ponds (BIG slitherers! 1.8 -2 m long) and they find octopus very tasty indeed :x So we have to remember which pond we have the eels so we can release and "extra" octopus in to the other one!
I have heard on very rare occasions that Moray eels and Octis will share crevices, dens, burrows etc.
I'm not brave enough to try that tho' (not that we get Morays down here....to cold or something!!)
J