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First-time octo owner has a few questions...

Bio Teacher

Blue Ring
Feb 2, 2008
Hi all,

I recently purchased a small vulgaris for my classroom, and everything seems to be going well.

I'm a little concerned, however, that he's not eating. Currently, the 75-gallon tank is full of live freshwater ghost shrimp, two scarlet hermit crabs, and a damsel. He's been in the tank for a week with no evidence of eating.

About twice a day, I'll lift up the live rock he hides under to show my students. I know the light and other stimuli are stressful for him, but it's hard to resist the temptation when the students are begging to see the exciting new octopus.

Here is my question:

Will my octo eventually become accustomed to moderate light and interaction, or am I killing it with stress?
Is it naive to think that I'll be able to teach him that the classroom stimuli (lights, students, etc.) are not a threat and that he's safe?

The octo's health and well-being are my top concern, so I'd like to know what you think.

Thanks in advance,

Welcome to our board.

You shouldn't lift the rock, and you should probably remove the damsel. They have been known to pick out octopus eyes and are just really territorial fish.

What kind of lighting is on the tank?
Thanks for the reply Animal Mother, and the welcome...

I just have a 15W florescent on one side of the tank for aesthetic purposes. The classroom lights add a bit as well.
I initially took out the damsel, which was my starter fish, but put him back in. At this point, I would be relieved if my octo eats him :smile:


yea when you lift up the rock it just stresses him out. also try putting an emerald crab or fidler crab in the tank. i know it's hard to wait because i just recently got my octo about a week ago. now he is out all the time and explores the tank. just be patient and he will come out.
i'll agree with Animal Mother about not lifting the rock and with permanently removing the damsel. you might want to try red lighting: octos can't see red, and therefor it appears to them that the tank is dark. the downside here is that the red lighting could affect growth of cyanobacteria, so more maintenance would be required in that aspect.
how long has the octo been in the tank? it often takes a week or two to settle into a new environment, and lifting the rock is going to cause him to be reclusive for alonger period of time.
make sure that the students don't EVER tap on the glass. the vibrations through the water will harm the sensitive octo.
this kind of stress will cause even more hiding.
some octos are just naturally reclusive and/or nocturnal. they may not come out or become tame at all. personally, i don't think such a sensitive animal belongs in such an environment.
Have you cycled the tank, if so for how long, it usually takes 3 months for a tank to be mature enough for a ceph. also, fresh water animals are usually not good nutrition for salt water animals, you will want to use fiddler crabs, or salt water shrimp for food. If you could post pics of your octo, it might help us identify it, just in case its not vulgaris, companies more often than not have no idea what type of octo they have, and just name it some random name they find. If the octo is old, it could be going through senescence(sp?) which would explain its lack of eating. You might want to check water quality as well, just in case. octopuses are very sensitive to water quality

oh yeah... :welcome:
Also if you have fresh live rock, the octy may well be eating amphipods etc on the rock.

We find that telling the kids (In a small public aquarium) that moving the rock all the time is like a mean giant lifting off the roof of their house to see what they're doing... it does seem to help the kids understand why they can't do it all the time. Make sure the dank is in the dimmest part of the class room and perhaps change any lighting on it for red lights (octis can't see that).

If he's young he'll probably get used to the kids being around if his home is left alone (ours get used to many people around and being photographed!) and he can come out in his own good time. I've attached a couple of our classroom activities that the kids might like to do.




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Thanks Jean, L8, daddy, and Fish for the replies and the advice,...

Starting tomorrow, no more rock lifting (hopefully I haven't created any long-lasting anxiety in the little guy).
Also, I'll order some fiddlers and marine shrimp for food.
I'll work on getting a photo posted. I know he's some type of brown Atlantic octo.
From arm to arm, he's about the size of my hand, so I assume that he's relatively young. I can't imagine that being the full size of a vulgaris, if that's the species.

The tank's been up for about two months. It has live rock and carbon filtration, as well as a protein skimmer. Also, I've read that water O2 levels are extremely important, so I have multiple air stones and a (covered) power head with high O2 input.

Again, thanks everyone for the help. If my octo could post, I'm sure he would thank you too for ending the live rock lifting :^D

Great activities Jean, awesome, thanks!


Air bubblers are an issue. Cephs don't seem to do well if there are bubblers in the tank. The air can get trapped in the mantle cavity and that's fatal. Get them out! Unless you can change them into air lifts which are essentially hollow tubes attached to the undergravel filter and the airstones go into the tubes. The idea is that water will be sucked through the filter and bubbles will be discharged at the water surface, hopefully out of range of the mantle. The power head should be fine and is probably capable of oxygenating the water with out the bubblers.

:welcome: and I'm glad you're asking good questions. I'm concerned that the octo isn't eating, since although the freshwater shrimp aren't that nutritious for them, usually octos consider them pretty appealing. It's not unusual for a new octo to hide for a long time, weeks sometime (and lifting up its rock may extend that), often they will come out at night and eat. However, a very common reason for an octopus to not eat is that there are water quality problems. I didn't see an answer to whether you had cycled the tank for three months (although since you mention the damsel as a "starter fish" I expect you have) but sometimes adding a large octopus to the tank can cause even a stable tank to go through a mini-cycle, so it's probably a good idea to do a water change (maybe 20%), and it's certainly a good idea to check the water parameters.

If it's that big, and it's U.S. Atlantic, it does sound like it's a vulgaris or briareus. If it is a vulgaris it is likely to outgrow the 75gal tank eventually-- they get quite large. Pictures might help us make sure of the ID, or look at pictures of briareus-- there were a lot of briareus for sale a few months ago, so a lot of people have them right now... I think the "Conan the Destroyer has Eggs" thread has some good pics.

A few other things I'll mentioned, although you seem to have researched things well enough that they're more for completeness: if the tank ever had copper-based medicine used to treat fish diseases, that stuff stays in tanks pretty much forever and cephalopods are sensitive to the copper at even trace levels. Unfortunately, there's not really anything you could do about it, but you can test for it. Also, you don't mention your octo-proofing strategies, so I just wanted to make sure that you've taken care of that.
Does your "brown" octo have false eye spots (blue)? Do his arms look almost stubby? This year has been a big one for Hummelincki which are more daytime oriented than the Vulgaris. Take a look through the Journals section and see if any of the photos look like your new student.
Bio Teacher;110499 said:
From arm to arm, he's about the size of my hand, so I assume that he's relatively young. I can't imagine that being the full size of a vulgaris, if that's the species.

Just to clarify... are you using "arm to arm" to refer to the span from the tips of the arms, or the base of the arms (across the mantle)? Sorry if it was clear to everyone else and I'm just being dense.