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Bimac Vs. Vulgaris


Jun 23, 2004
I'm a little confused on something.

If the O. Vulgaris lives around 12-18 Mo.s(If I read something that stated it wrong please correct me.)

And the Bimacs live around 6-12 Mo.s, why do most people recommend the Bimac?

Is it a question of availability?

Also in the "Checklist: Things to Think About Before You Get An Octopus as a Pet" Nancy states that a Bimac should have at least a 50 gallon tank but only says that a Vulgaris would "require a much larger tank". What minimum size exactly is recommended for the Vulgaris?

you know, i've been wondering about that too. i think it's probably availability, but i'm not sure. anyone who can answer Watcher's question better, please post a message! :biggrin2:
I think the minimum for a vulgaris is 120 gallons or larger, most people choose bimacs because they stay relatively small and vulgaris love to find ways to jump out of the tank.
Vulgaris can develop a 2 meter (6 feet) armspan--from armtip to armtip, whereas bimaculoides can achieve only a 0.6 meter (2 feet) armspan, if my sources are correct.

3 times the octopus would require 3 times the tank size, so ~150 gallon minimum.

In addition, they're nocturnal, so you probably wouldn't see your octopus as much. Unless you're a night owl, have a huge tank, and are willing to fork over the cash to feed the huge 15 pound beast, bimaculoides is a much better option :smile:
First of all, the bimac is now bred in California, and you can get a 2 or 3 month old bimac. Last year many of the bimacs lasted about 10 months in a tank - this generation may live a bit longer since they're younger. Bimacs often live more than a year.

O. vulgaris is not just a species, it's a species complex. If you are even lucky enough to get what you order, you might get the Common octopus body to about 10", arms 40", or the Caribbean common octopus.(body to about 8", arms 32").

O. vulgaris is known to try to escape much more than bimacs.

O. vulgaris is a sizable octos and would require much more effort and food to maintain than a bimac. It would be wild caught and older than the bimac babies - so you begin to lose your advantage of the slightly longer lifespan (I've usually read 1 1/2 years for vulgaris).

So the answer is partially availability - we have a reliable source of captive bred bimacs, but not of O. vulgaris. The difference in lifespan is not so great, and the large tank size and cost of feeding will add considerably to both expense and effort in keeping O. vulgaris.

People enjoy keeping bimacs, and those who've kept O. vulgaris have found them good pets, too.

As for recommended tank size, I would think over 100 gallons, maybe Nick's suggestion of 120 gallons is a good one.

Lifetrance, you slipped in there with a response while I was writing mine!

We had some big bimacs last year. My Ollie weighed over 3 pounds. It was hard to measure her, but her mantle was 7 or 8 inches and I saw here sit in the middle of her 46 gallon tank and reach out to all corners - so her arm length was at least 18-20 inches. This would give her a 36 to 40 inch armspan.

We had reports of two other large bimacs (and yes, Ollie was a bimac and had a perfect bimac ring in her eyespot).

So there were some bimacs who stayed smaller and some who grew larger. Maybe it's that way with other species too- we know so little at this point.

Thanks to everyone who responded.

Thanks Nancy, I understand now. I keep coming across baby pictures then. I wanted an octo that was larger than my hand. I didn't realize Bimacs got that large.
I am sure that nancy will be able to post a picture of Ollie against her or Bill's hands... I think there was a few goods ones for scale :smile:

I wanted to add that lifespan is entirely linked to water temperature and conditions, therefore suggestions on age are mostly guesses other than specific cases mentioned.

As a species, vulgaris can live in a water temperture of about 10 degrees C (~50F) and would live for possibly two years, However at 20C (~72F) it may only live 8 - 10 months....
Here's the pic with my hands, so you can see how large Ollie was. Many of the other bimacs stayed smaller than this.

I have small hands, so you can see that she was substantial. And she was very gentle and had the softest touch with the tips of her arms.

O. vulgaris are most sought after by public aquariums and is often confused (by hobbiests) with the GPO which is much larger.

As of the winter one of my suppliers (who happens to supply public aquariums around the world) informed me that there was a waiting list for the O. vulgaris. (of like 150 aquariums!)

Any hobbiest is much better off with a bimac or O. briareus (If you want the look of the O. vulgaris you might like the O. briareus which is much smaller and more similar in size to the bimacs.) IMHO. They can be kept in much smaller quarters and do not require the massive amounts of food as the Vulgaris.

Just remember that the bimac is a cooler water octopus while the O. briareus is a tropical species.
Post subject: Bimac Vs. Vulgaris

Hello Alicia,

Are you aware of a source for captive bred O. briareus? I am trying to be responsible about my selection for my first Octo, and because of the fact that the ol' budget doesn't favor the cost of a chiller, I feel that O. briareus would be a more ethical choice for me than a bimac. I am new here, but have been doing quite a bit of research on this and it is starting to look like there are no suppliers successfully breeding O. briareus in captivity. :? Can you confirm this? Thanks in advance.

Allow me to answer partly, Alicia may know more...

To my knowledge all briareus that I have seen for sale, discussed on this forum or kept myself have all been wild caught...

They are a species worthy of being captive bred and hopefully that will come soon :smile:

They have laid eggs for many people in captivity but rearing eggs/babies is the tricky part
Colin in correct in stating that O. briareus have not been successfully tank raised. The only way to obtain one is to get a "wild caught" O. briareus. Be sure to tell your LFS when you're ready for one and give them the scientific name. (Request they call you when it arrives so that you can acclimate directly to your tank. This makes less stress on the creature from water changes.) Many Octopus are "unidentified" or listed as "common" in the trade. If you tell your LFS that what you want comes from the Caribbean it will be much easier to accurately locate one.

If you're ready this summer now's the perfect time to persue a young O. briareus. If small in size, they will most likely have been born in the early part of this year. Thus a longer lifespan in your tank. If you wait till winter you will almost be guaranteed an adult. I hope this helps. Good luck!
Also, you might be able to lower your tank temperature for a bimac without buying a chiller. I lowered mine several degrees by keeping the air conditioning (and the furnace) set a couple of degrees lower, by having a fan blow on the sump, and by using the protein skimmer mostly at night, when the house was cooler.

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