Welcome to TONMO, the premier cephalopod interest community, and birthplace of #WorldOctopusDay and #CephalopodAwarenessDays. Founded in 2000, we are a large community of experts, hobbyists and enthusiasts, some of whom come together when we host our biennial conference. To join in on the fun, sign up. You can also become a Supporter for just $50/year to remove all ads and enjoy other perks. Follow us on Twitter for more cephy goodness.
Cuttlefish...im not sure, but the Octopus Vulgarus..also known as the common octopus can grow up to 2 feet...arm length. Pretty large and totally fit for your aquarium. I recommend the octopus cuz their awesome to keep.
Be SURE to check out the "ceph care" section of this site if your in-experienced in keeping cephalopods in captivity.