They are a warm water species (72-78F), from the Caribbean. They can grow to about 30 inches long, mostly arm length. They need to be kept in a 55-75 gallon tank, the larger the better to give them plenty of room to stretch out. They eat crabs, shrimp, snails. Nocturnal, but can adapt to daytime life. Blue/green with mottled red and white coloration.
Provide lots of strong filtration, about 3 times more than the average tank, because octopuses produce MUCH more waste than fish. Carbon and a good skimmer are suggested in case of an ink incident.
O. briareus is a large-egg octopus species, and their hatchlings can be raised on copepods/amphipods/mysis shrimp.
Hope that helps.