I've had a friend with cephalopods namley a dwarf cuttle and a bimac inklet. They were species only tanks, if you're looking for a cephalopod like an octopus, I'd strongly suggest a cuttlefish instead, they're just as about intelligent and don't try to escape the tank. My friend also has a couple softies with his cuttle, it's interesting to see them hang onto xenias and change color. But one last piece of advice, cuttles and octopi for the home aquarium have a natural lifespan of only 1 year, some even shorter. *Exception is the giant pacific octopus, a cold water giant that lives for 5+ years, but get way too big for most aquariums.