Beginner question about choosing 1st Octopus


New member

I have never kept an octopus before and always wanted to. I have reef-keeping experience, but have been thinking about a species specific tank with an octopus.

I have been checking on basically three species which are: O. briareus; O. Bimaculatus and O. bimaculoides.

The tank that I am thinking of is a 55 - 65gal tank and I was wondering if these species are appropriate for this size tank. I know that most octopus are most active at dawn/dusk or evening, but was wondering if any of these or perhaps another species might be a better choice for more daytime activity. Also, I was wondering if any of the small species are less inclined to try escaping or if this is innate in all octopi?

I would appreciate you input as I am trying to lay the groundwork for this new tank and I would like to take the time to do it correctly from the beginning.

Your help would be greatly appreciated.

Thank you,
A good place to start if you haven't already is to read all the back posts on this bord for cephalopods. There you will find a lot of your questions have been answerd. But to give you a general run down the best octopus to get for your first would be a bimac, bimaculoides/bimaculatus.
They are not prone to escape, easy to feed and day active. I would recomend you setting your tank up and having it running for 4-6 monts before you add a octo. A tank size of 30gl or larger is recomended.75 gln is ideal and lets you have room for larger and more advanced cephalopods down the road. Lighting is not important but filtration is. You will need a filter system that can handle a large bio load. Sumps are good. A skimmer and carbon are a must. If you have further questions just ask.
On a similar note.... depending on where you get your octo... it may not be what it said on the box. All of mine have been sold as Octopus vulgaris. Needless to say, none of them actually are.
Depending on which part of the world you are in someone here could point you too the best dealer
would suggest Bimac from

would suggest Bimac from

I inquired about the Octos from both Cephalopoder and Octo Monkey and they are both SO knowledgeable it's scarey...I got my first Octo about 3 months ago, a bimac, per the suggestion of both of the above...he has been very active both day and night after about 2 weeks of adapting... we recently got a 2nd one for our classroom, again a Bimac...This one actually interacts with the students and is not the least bit scared of people...One of the students even "pet" the Octo...They're really cute too! As the experts stated above, the filtration (and a skimmer) is the most important thing...Mine don't seem to mind the light, but I guess some do...The tanks we have them in are 35 and 20 gal tanks and they're fine...Not sure if that'll be the case after a year or two, but....

They make a GREAT pet!

Andy where did you get your bimacs from? I am glad you are enjoying them. Once you have a cool octo, its hard to keep any thing else in a tank, well except other cephs.

Chris. got both Octos (both Bimacs) from might be disappointed in me, but i just set up a 120 reef tank - it's cycling Cephs in there, sorry...BUT, Octos (Otto) tank is right next door and he's watching everything...The one here is getting pretty big and the 2 legs are about 6 or 7 inches now...the other legs are well over 12"...I think i'm gonna pull the damsel out...i think he's bothering the Octo...he's inked 2 times in the past week and i think it might've been from the damsel...or it might've been me startling him...btw, what effect on the water does the ink have?

The octo at school could not be doing any better...the tank doesn't have a skimmer, but we do alot of water changes...the kids love it, although they also think Ms K and me are nuts...He swims alot, which is really cool...he also like to play with the net when you put it in the tank - you can really feel his strength that way...Also tried that with Octo at home and he's REALLY strong...

I saw a pic of your mimic on some sight...that is absolutely incredible and he from the pacific? fishsupply got it for you? are they trying to locate more? Do you have info about it posted anywhere? I'd love to hear more about it...


Andy, you might want to check for nitrates. I notice that high nitrates will cause a octo to ink more. They will also ink when scared or feel threatend. My mimic started to ink when I switched from reef crystals to instant ocean. Not sure if I just got a bad batch or what but I will only use reef crystals from now on.
You should have a way to run your water though some good activated carbon all the time. And put fresh carbon in as soon as you see your octo ink. I do regular carbon changes about once a month when there are no problems. If you have a good skimmer and carbon you really don't have to change water with a bimac. It wouldn't hurt to do a 10-20% change any way in the next few days. You should do a 20% change every 4-6 weeks for optimum conditions. I must admit I have gone 3-4 months with out doing a change with a bimac. They are very hardy and are near shore octos so they are used to changing water conditions. My mimic is way more delicate so I pamper that little guy. In large quantities ink can coat its gills.Usually thats more of a problen with cuttlefish they put lots of ink. If your quick you can scoop out octo ink with a net. Ink kind of clumps together.
My buddy Jack at fishsupply gets me all my octos and mantis shrimp. Jack is a great guy. He will try to get you what ever you want once he gets to know you, or you tell him I sent you. As far a getting a mimic goes.. They are cool, beautiful, very very very rare and harder to keep. The bimac is the best over all for a pet. I just love bimacs!!!!!
The mimic requires a deep sand bed, warmer water, and excellent water conditions. Mimics are sand dwellers and will only sleep under the sand. Mine will not touch pvc tubing for a home. Check out Its a nice site.


Chris, luckily the last time he inked I was JUST about to do a large water change - nearly 50%...I did that because as you said, the Nitrates were kind of high...They are still present, but reduced...I don't think i'm ready for a Mimic, but maybe someday once i'm better at this...when I did the water change, I did not change the carbon...I'll do that this weekend...I also have that thing in there which you recommended about a month ago - it's carbon and something else (the name escapes me)...If you know what i'm talking about - should I change that as well? I know it's supposed to last up to 6 months and planned on using it for just about 3 months...I do have a skimmer on that tank, but not on the one at school....The bak-pak is working pretty well lately, just think it needed to be broken in what is it that a skimmer removes? ALL readings are perfect with the exception of the slightly high Nitrates and i have reduced the temp down to about 72 degrees...btw, when he inked, it wasn't really that much and it discipated very quickly...I will try to get a picture of him for you if i can...

As always, thanks for your help!

Hi Andy,
The cuttlefish I have are far more prone to inking at higher temp's. initially I had a problem with nitrates too but i made a denitrification unit. Want a project??????? This thing I made was cheap to make and reduced nitrate from over 100 to 0 in about 8 weeks.

I will post a pic of what i made, okay, okay, its not pretty but it works....

I used a small powerhead to pass water through 100 feet of airline. When it passes through the first 50 - 80 feet or so of airline, bacteria which uses oxygen to convert ammonia to nitrite removes all the oxygen. Then the water is totally void of oxygen. The water then passes into a totally sealed glass unit full of bioballs (I'm sure there's a TM somewhere :) ) Then the oxygen-less water passes through the bioballs which are home to bacteria which like anaerobic conditions (without O2). This bacteria uses nitrate to live. To cut a long story short; the bacteria breaks down nitrate to harmless nitrogen!
Em, actually its dead easy to make..... I got plans from saltwater on about and then bastardised them to my design because glass is my cheapest comodity.

If your interested I can give you more details if you like......... send an email and i can send stuff to you.

I use chemi pure on my mini reef/ mantis tank. On my octo tank I use a filter bag with activated carbon in it. Its cheaper this way. That way I can empty the filter bag of its old carbon and fill it with new carbon every month.
A protein skimmer removes un disolved waste before it has a chance to break down into ammoinia. It keeps the water way cleaner and is a very important thing to have on a octo tank to keep water quality up. Skimming will also remove ink from your water quickly. Carbon will remove it as well.
Because of the cuttles I invested in an aquamedic 5000!
Cleaning a skimmer is normally messy but with ceph ink its even worse!
that contraption...

that contraption...

I have Chemi-Pure AND activated Carbon in the canister filter for the 35 gal tank with the Octo...Should I just be using the carbon? Should I change the Chemi-Pure if/when he inks the water? The water is VERY clean and clear without any smell at all...Just that the Nitrates are a bit high...I would be interested in learning more about that contraption that you built, Colin...Thanks!

If you have carbon on your canister you don't really need the chemi-pure. It won't hurt any thing, just preforms the same job as carbon for the most part. I think that if you have good carbon, you can skip the chemi-pure and save some money.