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Dwarf Octopus Tank

Nils Laicher

Blue Ring
Jul 22, 2017
Mooresville, NC
Hey everyone, new here and very glad there is a forum specifically for cephalopods and octopus. I've been doing some reading the past few weeks about dwarf octopus since I saw one at my lfs recently.

My setup -
10 gallon DT tank, 5.5 gallon sump with Refugium.
Currently a reef with several coral frags, a couple clowns and a watchman goby.

First off, I realize that a 10 might be a little small for even a dwarf octopus. I am probably going to upgrade to a 16 gallon bowfront in the next couple months. Would a 16 gallon be big enough to house a dwarf comfortably? And to thrive, not just survive.
Second, I also found out that it can be pretty hard to find actual legitimate dwarves that aren't just small juveniles of octopus that will get bigger. What species would be recommended for a 16?

And finally, is it a possibility to keep my clownfish that are the current inhabitants of the tank? I read through the article about tankmates with an octopus but would a dwarf still do that kind of damage?

Just postin here before I get way to far into octopus keeping, I realize that with my setup it might not even be a good idea. Any input is welcome!
The most common dwarf we keep is O. mercatoris, a Gulf/Caribbean species. There is also a common but not often seen in the trade dwarf that originates in the US/Mexican coastal Pacific, O. digueti (hard to visually tell the two apart. There is also a third (again Caribbean), O. joubini but it is seldom seen for sale and not properly identified when it does appear. If it comes from somewhere outside the US, it is unlikely a dwarf but we do, on a rare occasion see a dwarf from indonesia that looks like a juvenile aculeatus but is nocturnal and has not lived long in captivity (possibly a function of age).

A 10 gallon, even with sump is a bit small for a dwarf but the 16 (especially with sump and plenty of live rock) would be fine for even a pair. Should you decide to try multiples, be sure that they have already been housed together (preferably found together) as it is unclear if they will be aggressive if not raised together (we have had multiple successes with tank hatched siblings raised together).

The Posts with Info for New Octo Keepers Thread has a few links to topics well worth reading. Pay particular attention to the Box of Chocolates link as it discusses the our most commonly kept animals and talks about the difficulty in obtaining the species you think order. Finding out the origination of an octopus is often helpful in determining its species.

I am a strong opponent of ANY fish being kept with an octopus. Fish are not their normal food and often they will only eat the soft belly of fish they kill in the tank. My objection to fish is more for the sake of the octopus than for concern for the fish. Even in the wild, fish pester octos trying to steal bits of food. Often complaints of an overly "shy" animal will lead to the discovery of fish in the tank. That being said, O. mercatoris is a naturally shy animal and often difficult to observe.
Thanks for the reply @DWhatley, I think finding the right species of octo and making sure it's a dwarf will be the hardest part of all this. I don't think I'd be keeping more than one, just because the fact that I probably won't find 2 that we're raised/caught together. That being said, where would a good place to be online to find o. Mercatoris? On Liveaquaria, there is the Atlantic Pygmy octopus but thats o. Joubini and out of stock anyway.
I definitely will upgrade to a 16 before getting an octo though, if I'm going to do it I want to do it right.
Also, are there any problems between corals and octopus? I can't imagine there being any, but asking just in case.
Thanks for the links, will definitely check those out.
O. joubini would be fine but anything sold under that name is more likely to be O. mercatoris.

Yes, there are issues trying to keep corals with an octopus. It is possible to keep a very few soft corals that have VERY low stinging capabilities but hard corals (and many soft corals) can sting an octopus leading to infection.
Thanks @DWhatley, I went to my lfs yesterday and asked about how often the get octopus in, they only do it through special order. I asked if they are dwarves and the said yes but couldn't give me an exact name for the species. But at $140 that they're asking for an unidentified octo I'll pass. I'd rather look online somewhere.

The corals that I keep are not very aggressive, and no hard corals either. I would have to get rid of my torch probably, that's the most aggressive one I have.

I'll keep looking around and reading what I can, there's still a lot I have to learn about these guys!
Hey everyone, I'm back! and this time with some more interest.
I lost my train of thought on this over the summer, and focused more on the freshwater tanks that I have now and also on my reef. Unfortunately, I don't have my reef anymore, I'll just call it unfortunate human error.
I have recently started thinking about octopus now again, because I have a 20 long or a standard 10 that I could possibly set up for an octopus. I will most likely end up using the 20 long.
I've been doing a lot of reading again, and most importantly looking what species I could keep and where I can get them from. Right now, it seems like the octopus suitable for my tank are O. joubini and O. mercatoris
The thing that makes me most hesitant about getting one is their life span. I read that they both only get 6-8 months, and I'm risking buying an adult that only has a few weeks left anyway and might not even lay eggs to give me something to keep working with.
Another problem is availability. Liveaquaria has Atlantic Pygmy octopus right now, but from their pictures they look to be O. mercatoris rather than O. joubini.
Is there anyone on this forum that is actively and currently selling any octopus? The most recent one that I could find suggested by someone was @Danthemarineman, and that was in 2006. Not sure he still has any.
So my main question is:
What is the best species of octopus that you recommend for a 20 long? Something a little bigger with a better life span than the 2 smaller species listed above?
I know I don't have many options but I figured I'd ask here before I do anything else.
Filtration wouldn't be a problem, I have a couple nice sized HOB's + a canister filter I could put to use. Already have all my rock and substrate from my reef that I broke down.
This is a great community, really not a lot of other places out there with info.
Anyways, happy holidays everyone! And thank you to anyone whoa actually took the time to read all this.
I actually just gave my LFS a call to see if they had any octopus ins tock since I have seen them there before, and they said they had a Pacific bi-something in stock. Only $29.99....
Seems suspicious to me. Could they be referring to a bimac?
If so, it probably wouldn't be suitable for a 20, right?
I've read they should have at least 50 gallons.
The thing that makes me most hesitant about getting one is their life span. I read that they both only get 6-8 months, and I'm risking buying an adult that only has a few weeks left anyway and might not even lay eggs to give me something to keep working with.
Since we are still a long way from captive bred/raised octopuses, the longevity for after receiving it is an issue for any species, however, as you mentioned, it feels more negative when talking about a dwarf since their lifespan is shorter. One small advantage of receiving an adult female O. mercatoris is the likelihood of being able to raise a few hatchlings (not so with O. joubini).

It is unlikely you will see O. joubini properly advertised. All "joubini" have been O. mercatoris. The few possible true O. joubinis have been listed simply as something generic.

Pacific bi-something in stock. Only $29.99....
Seems suspicious to me. Could they be referring to a bimac?
If so, it probably wouldn't be suitable for a 20, right?
It is not likely to be a bimac since catching them in CA for resale is illegal but it would be great to get a couple of photos if you can. O. hummelincki (also known as O. filosus) is a warm water species that is often confused with the coldwater bimaculatus/bimaculoides. Haiti would be a likely place of capture but they are also found in South FL (we have not seen many since the 2010 earthquake). Unfortunately, a 20 is too small for both and you need to cycle the tank for 3 months before considering housing an octopus.
Thanks @DWhatley, seems I'll be sticking to the dwarf species then.
I need to got to my LFS later this week anyway to drop off some fish, I'll have to see if it's still there and if I can get a couple pictures.
Is there any way to distinguish the difference between a male and female O. mercatoris?
This project is by no means happening soon (unfortunately:rolleyes:)
Frome experience with other critters that like an established tank, I'm definitely going to make sure I do that with this as well. I'm just trying to get some information together and some background before I get too deep in this.
Here is a post with photos and video showing the hectocotylus (mating arm) of a male octopus. The only way to visually guess a female is the absence of a hectocotylus. However, it is unlikely that you will be able to choose. It is not uncommon to acquire a fertile female though which may be because she is out foraging before laying her eggs.
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I wouldn't mind having a female that lays eggs for me at all. Thanks for the link, but I don't think I'll be able to choose which one I want if I will be getting one online. I'll have too see what's available near me.
I'll have to update this with any further questions I have or if I make any more progress in the process of setting up the tank. Thanks for all the advice.
Thanks for the link, the shipping seems a little weird though and I don't know if iw ant to drive all the way to my closest airport to pick up an octopus.

I went through with the octopus tank today, set up the 20 long with 15-20 lbs of live rock and a HOB filter as well as heater and a small circulation pump (Rio 90)
I went to the LFS today to check out the octopus they had and it was labeled as a Pcific Brown octopus, which is super vague. But I chatted with the owner for a long time about it and he said that he's had people buy the exact same ones as the one they had and they haven't gotten too big. So I'm wondering what it could be. They regularly get some in he said and can always get one if I request one. And it was seriously only $29.99
I couldn't get a very good look at it, as he was in a hamster ball which was in a stocking to keep it at the top of the tank. I could tell he was brown and about the size of a quarter.
They also said they got mimics in every so often, but I'm not willing to support that if there's a unknown population in the wild. That's what I recall about reading about them. Unless it's changed, I'm keeping my hands off those.
I started the cycle today with some dead shrimp in a media bag, and will be testing water the next couple weeks. I'll probably throw in a few chromis just to keep it cycled until the tank is established enough to keep a octopus.
Can I keep macro algae in this tank? I don't see why not, just haven't seen it in a lot of other octo tanks. Just was thinking some calurpa.
Anyways, lets get KRAKEN (crackin:wink:)
Macro Algaes are fine but need more light than most octopuses will tolerate so you will not likely see one out while the lights are on. You can experiment with more lighting during the hour your are not home and less when you hope to see the octo.

Pacific brown, as you acknowledge, says nothing about the animal but is a common term used by importers, suggesting this is an animal from the Philippines.

20 gallons is too small for anything but a dwarf. However, you may keep a pair in a 20 gallon tank. I am not sure where you determined that the Salty Bottom Reef Company (linked above) would only ship to an airport. They do offer overnight (required for an octopus) via UPS (and FedEx if you request it). However, they do not guarantee live arrival. They are in FL so the animal will be local. I have never ordered from them so I can't offer an experience.

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