Octopuses are sometimes kept as pets and are the most successfully kept cephalopod. They need to be kept in a "species tank", a salt-water aquarium devoted to one octopus. Although most of these octopuses are "wild caught", there are people trying (with some success) to breed octopuses to sell as pets. The most popular species seems to be O. bimaculoides, a small California octopus that lives near the shore and is active during the day. Other types of octopuses found in peoples' homes are O. vulgaris...

Octopuses are sometimes kept as pets and are the most successfully kept cephalopod. They need to be kept in a "species tank", a salt-water aquarium devoted to one octopus. Although most of these octopuses are "wild caught", there are people trying (with some success) to breed octopuses to sell as pets. The most popular species seems to be O. bimaculoides, a small California octopus that lives near the shore and is active during the day. Other types of octopuses found in peoples' homes are O. vulgaris, various pygmy species, and the "Bali octopus".
Pet stores sometimes have them.

WOW what would you want one of those for.We used to find lots of young octopus on the beach when we were kids. You will have to be set up with a large salt tank as they can grow huge and ,by the way, what are you planning on feeding it?

Better check with your county marine department if is it legal ?