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Help (Octopus cyanea)


Pygmy Octopus
Oct 3, 2007
Okay, so I am getting ready to do some research on intraspecies learning Octopus cyanea (Hawaiian Day Octopus). I have chosen this species because I live in Hawaii and will be able to catch wild octopuses to be my test subjects. I have recently aquired a 125 gallon aquarium that I will set up as an octopus tank, this aquarium will be linked to another 75 gallon aquarium. I am a little worried about filtration though. I am on a college budget and cant buy expensive equipment. I am going to make my own sump, refugium, and protein skimmer and will run several kinds of bio-filtration. I will also have a copper filter that all of the water runs through. I am hoping that this will be enough to be able to keep the octopus alive and well. I am going to feed the octopus live crabs and other crustaceans that I will catch in the wild. I have a few general questions. First, I just want advice on whether or not this set up will be adequate to maintain chemicals suitable for octopuses. Next, I was wondering what people think of UV-filters because I am thinking of getting one. Finally any other general advice on how to keep an octopus and not spend a fortune or on behavioral research in general would really be appreciated. Thank you very much.

UV-filter is a no-no for octopus tanks from what I understand, some of the marine bio. carreer folks can tell you more about that though.

What chemicals are you speaking of? Other than ph buffer there's no need for any chemical additives, and even that might not be necessary.

Keeping an octopus without spending a fortune is not that hard considering you can catch live food for it. That is generally the main ongoing expense, adds up over the duration of the octos lifespan.

Are you planning on using the 75 gallon as the sump? If so, I would say that is very much so adequate.
A UV filter is not necessary, as long as you are able to keep the water quality within range. A protein skimmer is really not necessary either. Both are good additions but not required.

How many kinds of bio-filtration?? It sounds like you are preparing well, but going a bit over board, which is very easy to do. How many octopuses will be housed in the tank? I would stay away from bio-balls. They don't seem to work nearly as well as oyster hash does. If you are not going to have a denitrification setup, then water changes will be necessary in order to keep the nitrates below the recommended range of 20 mg/L. Especially with behavioral research, water quality must be perfect or there may be some question to the validity of the results. The water changes will also keep most other parameters in line.

I assume that since you are already researching this, that you have read Hanlon and Messenger's book on cephalopod behavior. That is definitely a must read if you have not read it yet and it has a huge reference list in the back to delve even further into.

:welcome: please keep us informed on how your research goes... it sounds like you've already found this, but just in case not, there is a lot of useful tank setup info in the articles tab at the top (under ceph care). The tank database might be helpful as well.

Oh, and I'm sure we'd all love to see pics of your octos, too!
Hawaiian fishing regulations have a minimum legal catch size of one pound for O. cyanea. At this size they'd eat a LOT, they would be very very active, and they would not be likely to act normally in a 125 gallon tank. They would try to crawl out. It might help to think of your hypothesis first, and then pick the species that makes the best test subject for your question.

Also- very little work has been done on cyanea in the wild. If it's logistically possible and safe for you to snorkel with them, then you will probably learn more about them by watching them from a distance (beign careful not to approach them) in their natural habitat. Remember- always have a buddy in the water!
Thanks for your imput everyone, to answer some questions, no the 75 gallon aquarium is a reef aquarium, they will only be hooked together through the sump to make the chemicals more stable. I was not talking about chemical additives but more was wondering if the system would be good enough to take care of the waste from the octo. I am using a lot of bio-filtration because I have it, and figure that I may as well use it because it wont hurt, I too do not like bioballs and am planning on using ceramic rings as a medium. I have not yet read Hanlon and Messengers book but will look into getting it soon. And in response to Mucktopus, I would consider other species but that would present many time frame problems. I am doing this research for an undergraduate thesis and do not have long to set it up or complete it. That is why I would really like to use cyanea. One option that I have is to petition through the Department of Land and Natural Resources here in Hawaii to catch younger and smaller octopuses. I also may have large outdoor tanks open to use for my actual study, this would make observation harder but if they would act more naturally then maybe it is something to look into. Thank you all for posting.
It doesnt seem like anyone mentioned this already but I think you said you would use a copper filter. As far as I have read, any use of copper is a really bad thing-like toxic. Can someone else here with alot more experience shed light on this cause that could be a quick disaster if your fater is filtering through it.

Sorry, I should have been more clear. I am going to use a filter to make sure that I get all of the copper out of the water because it is bad for invertebrates to be exposed to. Sorry about that, but thanks for responding.
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