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Setting up my first Octo tank


Feb 26, 2017
Ocean City, MD
Hello everyone. I am a long time lurker here, but this is my first post. I have read and enjoyed all the information you have shared and I really appreciate the community you have developed.

I have always wanted to keep a pet octopus, and I finally started on my journey within the last year. So far I have one FOWLR tank and one nano reef tank up and running and I am currently very close to starting the pumps on the tank that will house my first octopus!

I have a 65 gallon glass tank with an overflow in the center of the back wall. I have the double drain system draining through there (Herbie) and the return pump coming over the back of the tank. I have seen the guide for how to octo proof my overflow and I plan to make one of those covers sometime in the next few months while my tank matures. I have 160 lbs of black sand which comes to just over 5 inches deep. I have read the varying opinions on deep sand (Hi Colin!) and I understand that it poses somewhat of a risk, but I would like to try to make the most comfortable home for whatever octopus I end up with, and many of them would prefer a nice sand bed to dig into. I made some rocks of my own and sculpted them into 'Pride Rock' and will be adding live rock from my other display tanks in the next few days. (Currently it is only half full with some powerheads running) I will update with some pictures soon. Anyway, Hi!
:welcome:! We look forward to your new adventure. You might consider journalling your tank build out in our Tank Talk forum as it is often helpful to take photos and record your decisions for future reference and to help others beginning the process.
Here is a blurry picture of pride rock.


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10 days into cycling now. Scaping is complete. Starting to get some good color on my white rocks. Final order of supplies will be here in a few days, and then I will just need a lid.


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You will want to add something more for denning. An octopus MUST be able to hide or it will become stressed. More live rock would be ideal but a large shell or even saltwater safe ceramic ornament (we have seen skulls, ship wrecks and other interesting displays) are fine.
Where would you suggest? I tried to leave space behind, between and under things as well as leaving 6 inches of sand to dig in.
I think maybe I will look into a shipwreck or something.
Your caves are a good start but octos need to be able to hide. As much as we want to be able to see them, they need places where we can't so adding more rock to your cave beginnings to block the light (and the view) and making them deeper will help. For a dwarf species, a cluster of variously sized giant purple barnacles (note the link is for reference and not a recommendation, I do not know anything about this vendor but eBay is one of the best places to find them if they are not locally available) have been well received.
As I am reading this I just left Home Depot. I got some PVC pieces to make a giant rock cave/overhang/PVC type deal to add to the front left. I may end up eliminating/covering the left side glass and going with 2 display panels. Either way he/she will have some awesome caves before they arrive.
Yes, I suspect that will be a better den or at least hiding place when it wants to be hidden. You might also add a few rock frags 1/4 to 1/2 the size of the pipe openings so that the octopus can make a door. Most of the animals I have kept prefer a cave with two openings (like your pipe) but O. mercatoris seems to prefer only one.

Upgrade my cave work. Is it okay to have a light on just the right side and leave the left all shadowy? I was thinking pride rock with a beam of sunlight but the elephant graveyard dark and gloomy. And then a red light at night or whatever?
Cephs don't need tank lighting but without it, we can't see our critters as well and photography becomes difficult (flash not recommended). You could have a successful octopus tank with just your room ambient lights so having only part of the tank highlighted is likely to be a plus, not a minus (and will help some with nuisance algae). That being said, if you intend on putting any kind of soft coral in the tank, you will need enough light to allow it to feed and will need to place it under the lights.

How are you securing your rock around the pipe? In general, this amount and size of rock is not a danger to an octopus but, if it is not secured (and sometimes if it is), it may get disassembled by the octopus. My tanks have been "rearranged" many times :biggrin2:
A note of caution about blue lighting. There does not seem to be any negatives about blue for daytime light but it is thought that blue may be seen as a brighter light than even white and is (without tested analysis) suggested not to be used as night lighting (ie "moon" lights). If you want to light the tank at night, red light is thought to be seen as no light and has been used very successfully to observe nocturnal behavior. Do note, however, it is miserable for photography.

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