• 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.

octopuses with tank divider


Oct 10, 2007
Hi, i was thinking of getting two o. mercatoris and keeping them in a 30 gallon tank with a divider in the middle so theyll each have 15 gallons each, then i would drill holes in the acrylic divider and cover the holes with netting to keep the octopus from slipping through. These will both be wild caught so hopefully one of them is a female capable of laying fertile eggs, which i would love to rear, and possibly send some to Tonmo members if anyone would be interested. I was wondering if anyone had tried this divider technique and if this tank would be big enough. I am not experienced with keeping octopuses though i do have a reef tank with several fish and corals, so i am not new to saltwater tanks.
anything would help. thanks.
I think you would be better off trying to acquire a WC pregnant female. No one of recent times has had any success putting two together adults in a tank. Raising babies together seems to be the way to go if you want them to breed as they don't seem to be agressive when raised in the same tank (or at least so far so good for me :wink2:). I am hoping to complete the life cycle in a month or so with my own as Miss Broody has mated with HideNSeek , has shut herself up in her den and has stopped eating (I am hoping that will change in a couple of days).

If you care to review where I am with my lot see: Trapper 's babies - Tank Raised Mercatoris: [Octopus Eggs]: - Trapper's Babies - Tank Raised Mercatoris

And my first thread on raising the mother, Trapper is finally here:
[Octopus]: - Trapper - O.mercatoris
:welcome: to TONMO... dwhatley is the resident expert on this sort of project, so I certainly can't add anything...
ok thanks, just wondering tho, do you have any problems with the fact that they breed within the same family? like brother and sister. Also, what size tank do you keep yours in? and do you know were i would be able to get a pregnant female? i have access to wild caught ones from a collectioner but it wont be guaranteed that it will be a female or if it is that it is even pregnant.
Thanks Monty, but I am hardly an expert (trying to be though, give me a few octo years/generations)

Sometimes DanTheMarineMan (TONMO name) has a collection of them available. From Mid-December through about March they are often plentiful because of the stone crab run (the get into the crab traps). My best recommendation from the little I have learned is to look for one with the fattest, biggest body. Sometimes females will lay eggs in their holding cup at a collection facility and you can acquire the mother and eggs. Most collectors are small, family run businesses and you can dialog with them about what you want. You may not get it "tomorrow" but you have a better chance of obtaining a female this way. Another sign is to look for an enlarged sucker at the base (nearest the mantle) of at least three of the front legs. This will be a male and the sucker is about twice the size of the next largest (my best guess is it is for mating). If you acquire a WC adult female, the chances are very high that she will have mated (particularly late in the year). Octos can mate multiple times and will store the sperm separate from the eggs until the female is ready to brood. Trapper was with me for three months before she brooded her eggs. She had an extremely small brood. Her offspring, Miss Broody, mated one week and has isolated herself ever since so I think she will produce eggs shortly (or already has). There is no scientific approach to dealing with reclusive wild caught octos but these are my best thoughts. If you can view the octos available from your collector, pick out the largest one. My males seem to be smaller than my known female (I have two that I am not sure about their sex because I can't get a good look at them) and her enlarged mantle made me aware that she was manufacturing eggs even before she mated.

Yes, there is a risk of problems mating sibblings but what the risk is is unknown. Ideally, you would acquire two pregnant females and attempt to pair the separate broods. This would mean trying to raise roughtly 200 octo fry and separating them into pairs (or at least separating out the females) at the point of suspected sexual maturity. Even though you may keep multiples in a single tank, you can't keep a great number (three in my 45 seems to work but one is only seen once about every two weeks). Even dealing with 100 will be expensive and difficult. If you live close to the ocean (the one where the octos came from only) you can release some of the fry to minimize the numbers but the cost and time are still high. If you are expecting to make a profit, I fear you are in for a disappointment. The adventure is well worth it but the financial and time costs are high.

Whatever approach you take and whatever the outcome, please start a journal on the adventure.

If Roy Caldwell (who really is an expert) happens to read this post, he may be able to offer some insite about problems with sibbling pairings. I am mulling over what to do if my sibblings produce healthy young but am thinking and waiting to see what transpires over the next couple of months.
ok thanks, i mainly want to do it for the experience not the profit, though it would be good to atleast get "even." Unfortunatley i cant actually see the octo because it is too long a drive (about 7 hrs) from Miami to Tampa but i will contact the seller to see if he can pick one out that appears to be a female. I was also wondering if it would be legal to catch one since i am going boating tomorrow off of miami. I will be going about 13 miles off shore to do some diving, and i might get lucky and see one. Would i be allowed to catch it? or is that illegal?
I can't help with the legal aspects. Florida has it's own fishing laws and they have always been more open than California but have been getting tougher over the last 10 years. I would think you would need at least a fishing license (that may not be required that far out though, thinking about it) and you might be able to ask if octopuses are included in the general license as long as it is for your own use and not resale. They are not endangered and should be considered the same as fish but checking with the license people should be a way to verify.

However, if you find a Mercatoris the chances are it will be a dying animal. From what I have observed in three animals as well as reading other keeper reports, the only time they are out during the day is during their last week of life. Mercs are nocturnal, shy and stay in their dens until after dark. You would not be likely to extract an animal from its den and taking out live rock is illegal. There are two others that are found in the trade and common to the area (Briarius and Vulgaris) that tend to be out early in the morning and early in the evening and sometimes during the day but the Mercs are only night time creatures.

I have accustomed my babies (I guess I have to stop calling them that now since they are actually full adults now) to feed between 11:00 PM and midnight but their mother did not respond to feeding that early until after she started brooding her eggs and was always in her den. I have one that will come out shortly after I sit in front of the tank and he will stay active while I am there for between 20 and 30 minutes most days (some days he wants little to do with me and others he plays for longer periods). In the wild they are normally very shy and are not the ones you see playing with divers. They are usually caught as by catch in live rock or other containers.

Trending content

Shop Amazon

Shop Amazon
Shop Amazon; support TONMO!
Shop Amazon
We are a participant in the Amazon Services LLC Associates Program, an affiliate program designed to provide a means for us to earn fees by linking to Amazon and affiliated sites.