• Looking to buy a cephalopod? Check out Tomh's Cephs Forum, and this post in particular shares important info about our policies as it relates to responsible ceph-keeping.

What CAN live with an octopus?


Blue Ring
Nov 13, 2006
I am getting ready to set up a new tank for my octopus that is living in my invert only tank. I am just curious as to what I can actually put in the tank with him. i.e. star fish, snails, slugs, plant life, etc.

Is there anything that can co-exist with them?
Mostly, it's hit or miss. All octos are different, so even though one of us could have great luck with stars or slugs etc., another person may have a completely different experience introducing a tank mate.
I had stocked my octo tank with black foot trochus and hermit crabs prior to my octo's arrival, thinking they would be food at some point.....but they are all still alive and he pays no interest to them. However, some people on this site could tell you their octos have eaten plenty of hermits.
A few months ago, I did introduce a chocolate chip star to the tank. My octo was clearly not thrilled about this five-armed moving thing, and spent the first 48 hours harrassing it and trying to pry it off the tank wall....could have been curiousity, I'm not really sure; but they live together just fine now.
Make sure to research the animals you are interested in keeping in your ceph tank - some can give off toxins when stressed or dying which could ultimately wipe out your whole tank, others could hunt your octo [Fish are generally not a great idea for tank mates]. But always keep in mind, whatever you put in there could end up being dinner for your octo one day, so I'd recommend not spending too much!
Thanks, I certainly don't want anything that could hurt him.

I have had 9 chocolate chip stars (Harlequin food) in his tank since day one, one hermit he could care a less about and one shrimp. I feed him one glass shrimp a day and he eats those right up so I am not sure why he won't touch the other shrimp I have in there. Maybe they are pals LOL

I just want to find something else to put in his tank because he is nocturnal so we only see him after 8:00PM.

How about plant life, any experience with anything along those lines?
i think some ceph keepers here like to put some caulerpa in their tanks, but I have zero experience with this.... :smile:
I have caulerpa, and red kelp in my bimac tank. he pays no attention to it. Except that the red kelp is obviously red, which octos cannot see. I think it kinda freks him out a little bit when he bumps into it.
Caulerpa is probably the easiest macro to grow, but it takes extra effort to maintain. It will take over if you don't prune it regularly, plus portions of it will die off and if you don't remove those parts before it dies off, it will ruin your water quality. Plus, as Dan pointed out in another thread, it is illegal in some states because of the fact that it takes over if not properly discarded.
Serpent Stars are considered an acceptable tankmate, if you can find a red serpent star they are very brightly colored and grow pretty big, fun to watch move around when they sense food.

LiveAquaria.com sells them... :)
As weird as it may sound i have skunk shrimp, and a frogfish and about 10 hermit crabs, he touches none of them at times he has even played tag with the frogfish but as soon as I throw a fiddler crab in the tank its chow time!, I know this is not the norm, but I guess its all about the feelings of the octo!
Some members of Tonmo have had seahorses, fish, and even rays in tanks with their cephs...it really is dependent on the particular cephalopod. Most of us err on the side of caution, but certainly serpent stars are alright. (whoa...say that three times fast)
I've contemplated putting Einy in one of our seahorse tanks considering he's A) a dwarf, B) not very active, C) doesn't eat snails.

BUT, I most likely won't because I'd never see him with all the rock and corals. Not to mention, if he did kill someone, my girlfriend would kill me, and vice versa.
...and therein lies the big problem, you just never know! If you do decide to keep your octo with another animal, make sure it isn't one you are going to miss.
g/day i have about 8 hermet crabs and 3 sea urchans 3 large sea slugs
and they dont bother homer the occy but as soon as i put any type of fish or crab in there he dances his jig and there gone
Thanks for the input everybody. I think I will start with the star fish I have in with him now and the shrimp he seems to like. I had a hermit in there for about a month but it appears as though my octopus finally decided to "have a taste" LOL.

I am going to keep my eye out for a serpent star, they look pretty cool. I actually have a tiny serpent living in the live rock but it's very small and i've only seen it once.

I would really love to be able to keep sea horses in the tank as my wife REALLY wants one but she would loose it of the octopus killed it.

How about corals? Are they any that would be okay? I just want to liven up the tank a bit. It sits right beside my reef tank and looks so quiet and lifeless. If I can't put any corals in there I might get some fake plants, any problem with that?

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