Octopus are stunningly beautiful, fascinating, and intelligent marine creatures. However, they are not easily kept alive and healthy in captivity. Therefore, octopus tanks should only be attempted by advanced saltwater aquarists.

Procuring Octopus

Most octopus are taken out of the wild, though there has been some success tank-breeding Bimaculoides, also known as the "Two Spot" octopus. This species inhabits the mudflats of California, and is one of the hardiest and most adaptable to life in an aquarium. Wild-caught octopus are notorious for stressing and sickening during transfer. Plus, identification of wild-caught species can be difficult as octopus change color and shape to blend into their surroundings. Being certain of the species of octopus you are getting will insure that your tank's temperature and water conditions are appropriate, and that your tank is large enough for your particular breed.

The Octopus Tank

Even the smallest octopus needs a large tank and plenty of filtration. A 50-gallon tank is the smallest suitable for the dwarf species. Octopus are extremely sensitive to ammonia and nitrites, and require more flow and oxygenation than is present in most home aquariums. A good protein skimmer is essential. It is best to house all equipment (power heads, skimmers, thermometers, etc.) in a sump, as octopus will stick their tentacles into equipment and have been known to disassemble the workings of their tanks. A heavy lid is also a must, as octopus are natural escape artists that can fit through the tiniest hole or crack. Live rock is fine, but stinging corals and anemones should not exist in an octopus tank. The rock will need to be secured to prevent avalanches, as octopus are surprisingly strong and will try to redecorate. Octopus need caves and hiding-holes, which can be provided either by rock formations, or with man-made, aquarium-safe tubes and pipes. Most octopus are nocturnal, but low lighting may lure your animal out during the daytime.

Tank Maintenance

A tank inhabited by octopus can never be treated with copper, which is deadly to cepalopods. Frequent, aggressive water changes are a must, especially if the octopus becomes frightened and "inks" in the tank. Carbon can be helpful in octopus tanks, but must be changed immediately if the animal "inks."

Companions

Octopus are highly likely to eat any other creature living in their tank, including other octopus. You may be able to get away with fast-moving fish if the tank has plenty of hiding spots. Sea cucumbers and starfish might prove unpalatable to a well-fed octopus, but don't expect a cleaning crew of snails and crabs to last long.