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New dwarf octopus ID & care


Nov 23, 2003
We got a dwarf octopus (so I'm told) as a hitchhiker on Florida live rock. While it may not have the longest of lifespans, we'd like to try to care for it as best as we can.

We've put it into a 5 gallon tank, and it's the only resident (save the occassional crab that we can catch out of our big tank).

I'm posting a picture I took of it munching on the crab last night; it's now under a cave in the live rock. I'm going to keep up with the water chemistry (e.g. salinity, temperature, pH, ammonia/nitrites/nitrates).

Unfortunately, we're not going to be able to keep it fed with small live crabs for a significant amount of time.

Any articles, or suggestions as to how to feed dead food, what kind of dead food, etc.? Lighting (except for the live rock lighting needs?) Snails ok, or snails lunch?

Species ID? (please don't tell me it's Octopus chadii :smile: ) (For scale, it looks bigger than a marble, and smaller than a ping-pong or golf ball).

and Welcome to TONMO.com :welcome:

What a fine little octopus - glad you're going to try to keep him.

As for food other than live food, try pieces of shimp and scallops, preferably fresh. You'll have to see whether the little guy will accept frozen food. Not all do, and most have to learn to eat it. You could also try small pieces of fish. Yes, many octopuses will eat snails, if they're in the mood. He seems to be a good size for hermit or fiddler crabs. Even if you're feeding mostly dead food, it would be good to supplement with live food occasionally.

As for the lights, octopuses don't need bright reef-type lights - probably what you're using for the live rock will be fine.

Your octo also needs a den, a big shell or some piled up live rock where he can hide and feel safe.

There is lots more info in our Ceph Care articles - look at the Equipment List and the Checklist
Cephalopod Care

Well, lokks liek it could be vulgaris as it seems quite a heavy looking octopus, maybe briareus but better closer pics will help!

What is O. chadii?????????????????? 8)
In a pinch, you can use an ABS elbow...from your local hardware store...as a hiding place. Some octos like it because it is smooth, and nice and dark.
Good luck!
I actually think it's Octopus mercatori. I have a dome-shaped piece of live rock in its tank that it can (and does) hide under from time to time. PVC is a good idea, I'll add that as an additional nook & cranny.

He did take a piece of raw shrimp from my wife today (on a skewer, not from the fingers :smile: ).

Even with the live rock, chemistry is still unsettled, I'll need to add more live rock. For now, it's water changes very frequently.

How frequently should they be fed? Once a day? Every other day? 3x/week?

this is interesting, Our original system several years ago had such a hitchicker, but we didn't even know until after re-aquascaping and he scuttled one of our rocks. Under the rock he came out of we found several piles of what we originally thought to be substrate particles turned out to be his refuse. He lived for about 5 months. Our next hitchhicker was a pair mantis shrip that we tried to isolate and they killed everything in our small tank and eventually each other in the course of 2+weeks!! Beware the :x hitchhickers :x
Our new project hasnt seen very many detrimental hitchhikers as yet and our Bimac is doing well. Sorry for the newbie jump-in here, i just had an impulse to share... :bugout:
melam said:
Sorry for the newbie jump-in here, i just had an impulse to share... :bugout:

I think I speak for everyone when I say nonsense and :welcome: to TONMO.com. It's always good to hear about others' experiences with aquaria (or do we prefer 'aquariums'?) and cephs. Especially for folks like me, who have no real experience with either (yet). :frown:


Looking forward to hearing more...
Hi Melam,

Um... is right, we're glad to have your contribution! And welcome to TONMO.com!

I'm amazed at how long after you buy the liverock, new things still appear from it. For instance, I now have a beautiful limpet and it's over an inch long (unfortunately, bimacs like to eat limpets in the wild, I've read, but so far Ollie hasn't discovered this particular limpet).

Thanks for the warm welcome!!

We are looking forward to the info exchange I see going on all over this forum so we can properly and successfully raise and keep our newest family member!! It has taken a while but I think he's getting used to things finally and we are getting a digital camera for christmas almost exclusively so we can plaster his handsome face all ove the internet!!

i have a few questions is a dwarf octo and a pygmy octo the same thing andis it really necesaryb to have a protien skimmer if yes any suggestions for a cheep one and which species octo could you keep whithout a heater
Yes, dwarf and pygmy are used synonymously. The most common we find available in the states are O. mercatoris from Florida/Caribbean and most often come from live rock farmers (hitch hickers in the LR) and occassionally from fish collectors who buy them from the crabbers (crabbing season did not yield many mercs this or last year though). There are a couple of other small Caribbean species but they only show up as a fluke.

What is the temperature of your tank? Caribbean species are successful from about 72 - 78 degrees but if your tank will be lower than that in the winter you will need a heater.

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