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Octopus for Animal Behavior class


Dec 13, 2002
Hello. I'm taking an animal behavior class, for which I've decided to keep an octopus to study. I've let the tank cycle with liverock for a couple of months, and I've added 12 yellowtail damsels to help cycle the tank, and perhaps feed the octo, although I don't count on him being able to catch them. My tank is about 1.5x2x4 ft. Could I fit an O. Vulgaris there, or would I be better off with a bimac or joubini (dwarf)? I've seen videos of vulgaris camouflage in action, and had hoped to keep one for that reason--do bimacs and dwarfs change color and texture as extraordinarily? I really want a vulgaris, but my impression is that my tank isn't large enough. Any insights as to my options here woud be greatly appreciated.

I'm lucky enough to have a bimac and a vulgaris, (in different tanks obviously).
While the vulgaris has a huge variety of disguises, I think the bimac has the edge in the camouflage department. Most day active species can change colour and texture suprisingly quickly.
Nocturnal species e.g. O.joubeni/bocki show very little of this behaviour. So don't get one of these if colour change is what you are looking for, you may be dissapointed.
While vulgaris are a bigger Octopus they don't seem to grow as quick as a bimacs. My vulgaris has grown about 300% in 9 months, the bimac has grown about 600% in 3 months. So your aquarium would bo OK for a small vulgaris, for a while anyway.
I guess a 10-20 gallon for a pygmy, 30-40 gallon would be fine for an adult bimac, and 100 gallon plus aquarium for a decent sized vulgaris.
Your probably better off taking out the damsels before adding the Octo, it will help it settle down. Small active fish can upset them intially, although they would make a nice snack once the Octo is settled.

do not go with the pygmy. if this is for a study thing. my only comes out at late night. i trick him by fully covering the tank but i put my head under it while its close because if the thing falls of he runs and hides for another hour. a good thing to consider is a cuttlefish if you can get one. he can change color alot and fast to. just a thought. i would go with the bimac.
Thanks--and one more question.

Thank you both so much for your help! I made more accurate measurements and found that the tank has a capacity of about 45 gallons, so I guess a bimac is the way to go. Just to be sure, what is the difference between bimaculoides sp and bimaculates sp, and which one do I want? Also, do you know what the usual lifespan is (assuming I keep him alive for a few weeks!)? I live near my school, so I'll be able to care for him over the summer and next year, but I'd still like to get some sense of the commitment I'm making. Again, thanks so much for your help!

Happy future octopus owner Rome :biggrin2:
Hi Rome

FYI bimaculoides is the one that is normally sold, it is easier caught normally at shallower depths.

bimaculoides is fully grown at ~ mantle 12cm and arms to 35
bimaculatus is fully grown at ~ mantle 20cm and arms to 80

Also the blue ring on a bimaculatus is a broken chain.

You want bimaculoides! :smile:


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