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Are we wrong about large tank sizes? read this...

Jan 10, 2007
i spoke again with a marine biologist @ Cabrillo Aquarium in San Pedro, CA and asked a few questions about the very large octo they have in the main center.

i asked how the heck they have a large octo in a tank that small...i was shocked, thinking of how long this octo's wingspan must be! She said it was about 60 gallon and that octos...get this....actually like smaller amounts of water! after i found an octo in an UNBELIEVABLY small amount of water in a tidepool, her theory sort of made sense.

the next question was: "how come you guys dont give the large octo a hiding space?" as you can see in the video (below) there really isn't a hiding space. She responded that this is a 7 year old Female who has become adapted to people and loves to be out & not hiding.

they have 2 more octos, and one of them in the "Discovery" area (next to the nursery) is also in a small amount of water. if you go there look for him, he's hiding in the tube part that connects 2 small tanks together.

so when i read on here that you need a 50-60 gallon tank for a small, common octo, i wonder if it's really true after what this marine biologist said. and, their octos tend to live longer than any of ours.

here's my video of their large, 7 year old Female octo:

I used to work at the Cabrillo Aquarium many years ago, before they remodeled. I cannot vouch for the current staff. But, when I was there, I would not have followed the advice of some of the staff members on aquarium basics. Just because they work at an aquarium (or LFS) does not mean they are a cephalopod expert. Yes, octopus like to have a cozy den to hide in, that does not mean that their entire environment should be small. Most aquariums also have their tanks connected to a larger system with either natural or artificial sea water. They also have a large filtration system to handle the waste. They don't have to worry too much about fluctuations in their water parameters because they have sooo much water. While a home aquarist would have to worry about large amounts of waste and fluctuations in water parameters in a small system.
There seem to be two issues regarding the size of octo tanks - waste and confinement. Which do you guys think is more important and why?
There are a lot of variables that go into the size of a tank for a octopus. I've kept octopus in 10 gallon tanks and they did fine. But its probably not the best thing to do. Usually GPO's are kept in really small tanks for there body size. Usually they stay in their dens but they also come out and hunt and walk/swim. You could say the same things about humans generally we live in houses and I probably could keep someone in one room there whole life but would you like to. So getting down to the point yes you can keep them in small tanks but most of us like to provide a better environment for them to live in. Also, just because someone says that its ok does not make it so even if they are a marine biologist.
A lot of public institutions don't have much money to play with and are put in an unfortunate choice of undersizing their displays versus not having them. The Mystic Aquarium in CT has a GPO in a disturbingly small cylinder tank--I suspect its not much more than a few hundred gallons. Even the Seattle Aquarium's display tanks aren't big enough for adult GPOs to swim easily.

Just because you can keep an animal in a small tank doesn't mean its best for it, and pretty much the universal opinion at TONMO is that you should try to do what's best. Its easy for a public aquarium to see entertai--err, educating the public as a more critical goal.

That tank at Mystic Aquarium is at least 5ft cubed. A quick conversion puts that at at least 930 gal. Might be bigger, but it has been a while since I was back there.
A 5' diam, 5' tall cylinder is about 733 gallons. Bigger than I thought, but still if the animal is 10+ feet across... The matter is moot for the moment since the current inhabitant has eggs. But its been my impression that critters at that aquarium get used to swimming around in circles pretty quickly.
Besides from the issues of water chemistry, you can get a pretty good idea from many species of octopus if they are in a tank that is too small by watching their behavior. If there isn't enough space to roam and/or good hiding spaces, the animals will start to "pace" much the same way that big cats and other zoo animals will. If you see incessant movement back and forth across the front of the aquarium, you probably need to move the animal to a considerably larger one. This certainly seems to be the case for blue-rings, A. aculeatus, O. rubescens, O. cyanea, and some other species we have maintained. It does not seem to hold for some pygmies such as O. mercatoris or O. bocki.

:mad: on:

Any one who says that octopus feel "better" in a small tank should be advised to take a basic marine zoology class. Yep, I sure would love to live in a small room, and use one corner for feces, another for feeding...oh hey, that sounds wonderful ! Ventilation? Who needs it ! After all, I can get by. It worked in WW2, didn't it?

Come on.

:mad: off
The point about the small tidepool is just silly. By its very nature a tidepool is only a tidepool for a short period of time, then the entirety of the ocean comes back and suddenly its not quite a small pool anymore!!! Any animal which lives in this kind of environment has to be able to survive the conditions of tidepools when the sea goes out... but it always comes back...

For ceph tanks BIGGER is always BETTER
nice pictures.i noticed different animals preserved in jars.i would like to get some of the solution used in them as i have a blue ring that has been frozen for ten years in my freezer since it died.any suggestions would be appreciated so that i can finally get it out of my freezer.
ob;93617 said:
:confused: 7 year old :confused:

Yeah, sounds like a crock o' "caca de toro" to me.

Any one who says that octopus feel "better" in a small tank should be advised to take a basic marine zoology class. Yep, I sure would love to live in a small room, and use one corner for feces, another for feeding...oh hey, that sounds wonderful ! Ventilation? Who needs it ! After all, I can get by. It worked in WW2, didn't it?


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