I Don't Want One But Just Asking.. [Archive] - Reef Central Online Community

TidePool Geek

07/10/2005, 04:38 PM

Hi Surfin,

In no particular order:

- Decent quality COLD water - Enteroctopus dofleini aka Giant Pacific Octopus aka GPO is a cold water species and needs water in the 50 to 60F range. Of course, you would want to strive for the best water quality possible but this species has demonstrated the ability to tolerate less than perfect.

- Space - In a roughly 3 year normal lifespan a GPO will grow from almost microscopic to 80 - 100 pounds and an armspan of 12 -20 feet. [FWIW: The size records for GPO's are just under 600 pounds and something like 30+ feet armspan. That was probably a non-breeding male that lived well beyond the normal 3 years.] Further, you need to make sure that the tank is escape proof. Keep in mind that a determined GPO can get through a hole that's less than 2 inches across and is strong enough to move a surprisingly heavy barrier.

- Food - Octos are among the most efficient animals on earth when it comes to converting food into flesh. Even so, to achieve that kind of growth rate a GPO eats a lot. Each year at the marine center where I volunteer we try to get a fairly small GPO (10 - 15 pounds and 4 - 6 foot armspan). Over the course of the Memorial Day to Labor Day season a happy GPO will eat two or three Red Rock Crabs per day (Cancer productus which weigh 1 to 1.5 lbs each). During this period the GPO will double or triple in size.

- Enrichment - This may be anthropomorphising a bit but GPO's are prone to boredom. Even though they spend most of their time sleeping in a den they are happiest if given something to 'think' about each day. The most recent enrichment technique that I've heard is to stuff a "Mr Potatohead" toy with shrimp or chopped herring, soak the pieces in shrimp juice, assemble the thing, and give it to the GPO for disassembly. IMHO: If you set up a tank with sufficient places for live prey to hide and fed only live prey, the enrichment issue would take care of itself.

Bottom line: Unless you have the good fortune to have a flow through system drawing from open salt water you'll need quite a large tank - 1000 gallons seems about right. Further, you'll need a really good filtration system since GPO's are such heavy eaters. Finally, figure on feeding around a thousand pounds of live food or a combination of live and frozen food during the last active year of the animal's life (not counting the 6 months or so that a female GPO starves during egg gestation). During the earlier part of its life the GPO will obviously eat less but the best choices for food will be more esoteric and may be harder to aquire if you don't live pretty close to the shore.

Of course, if your home or facility is on the water things get a good bit easier. At the center, we pump our water directly out of the harbor so we don't have concerns about nitrogeneous waste build-up or about chilling the water. Further, because of the constantly changing water we can get by with a somewhat smaller tank - we normally keep our GPO in a tank that's around 700 -800 gallons. To feed them we simply put out a couple of crab pots each day which yields sufficient chow for one GPO.

Because of their size GPO's are 'top' predators and don't get particularly high marks in "Gets along well with others". OTOH: There are a few things that can be kept with reasonable safety in the same tank as a GPO. GPO's don't seem to mind or bother anemones. A well fed GPO won't usually bother with such things as snails or limpets. Fish are another story - I suspect that any bottom dwelling fish would be at risk. Mid water fish may or may not be safe according to species; we've kept young salmon (to about 10 inches) with our GPO and, although we never lost one, there were numerous signs that the GPO had attacked them. OTOH: We've never had a problem with the GPO attacking Shiner or Pile Perch (Cymatogaster spp.). Echinoderms should probably be completely avoided although it's possible that Sea Urchins might be safe.

A GPO is almost a requirement for a public aquarium and they give us docents a long ton of information to impart to our visitors. OTOH: For a home aquarium it would be a high maintenance and fairly low entertainment sort of a pet.

Objectively yours,

TPG