smallest/best size tank for octopus? will be plumbed to larger system

justinm001

Pygmy Octopus
Registered
#1
I want to surprise my girlfriend who wanted an octopus but she was outvoted and we decided to do a reef tank. I'm wondering what would be the best size for a tank with just an octopus? It will be plumbed into my system with a 150gal reef with 100gal sump and 50gal growout tank.

I did a lot of research a couple years on cephalopods but forgot most of it and was wondering also what would be the best kind for a smaller tank. Also my water currently is 79degrees and I remember cephalopods like cooler tanks. Would this be a problem?

thanks for all the help, I'll be sure to make a build thread of the adventure.
 

CaptFish

Colossal Squid
Staff member
Moderator
#2
:welcome: Back to TONMO

I'm wondering what would be the best size for a tank with just an octopus?
This question is asked a lot, and usually we suggest a 65-75 gallon tank which is large enough to house any of the commonly kept octopuses. There is the option of going with a smaller tank like a 30 Gallon but you will only be able to keep dwarf species of octopus which are highly nocturnal. They will not come out out unless the room is totally dark and the tank is light with dim red lights. The dwarf species are also not as interactive as the medium and large octopuses. The upside to the dwarf species is that you can keep them in pairs. I have one now but I never get to see it. I go to bed to early.

I did a lot of research a couple years on cephalopods but forgot most of it and was wondering also what would be the best kind for a smaller tank. Also my water currently is 79degrees and I remember cephalopods like cooler tanks. Would this be a problem?
Octopuses come in two varieties cold water species and warm water species. 79 degrees is perfect for the warm water species which is the one you are likely to get, as we are unaware of anyone selling the cold water species at this time. The few we have on TONMO where caught by their keepers in the wild on the California coast.
 

justinm001

Pygmy Octopus
Registered
#3
I assumed the question was asked alot. I just wasn't sure if large tanks were recommended because of their large span or because of water quality issues. Currently I have a 36, 40, 75 gal tanks just laying around but was thinking about a 45gal cube (24x24x18) which would seem perfect to fit on our kitchen countertop corner. I thought all octopuses were very nocturnal any recommendations of type that would fit well and might not be as nocturnal.
 

CaptFish

Colossal Squid
Staff member
Moderator
#4
45 is really too small. plus The jury is still out on whether cubes provide any advantages or disadvantages with keeping octopuses. Octopuses need space to move around as well as volume to handle all there waste, and a very good filtration system is a must. Some of the cubes that have built in filters just don't seem to have great filtration, when compared to a good sump setup.

I'd setup the 75 if I were you.
 

justinm001

Pygmy Octopus
Registered
#5
It'll be plumbed into my system with about 300gals and very strong filtration(sump, skimmer, refugium, phos reactor, carbon reactor...) so I'm only concerned with confortable living space for the octopus.

If I setup the 75gal It would need to be in the kids playroom. I know they need tight lids but could I use some form of lid that might be airtight with airstones or something. Then I could keep it locked when not feeding so the kids don't get a bright idea of dumping orange juice or trying to take it out to play with or something.
 

DWhatley

Cthulhu
Staff member
Moderator
#6
A spill proof lid will cause heat issues as well as air exchange problems. We drill holes in our acrylic tops to allow heat to escape and have open sumps and splashing returns to keep good aeration. Octos need more O2 than equivalently sized fish. If the tank is still going to be plumbed to the larger system, you still need to worry about the heat build up but a heafty water exchange should provide the O2. Air stones will help exhaust the CO2 but if the top is too tight, it won't help alot with aeration.
 

Darth Kraken

Blue Ring
Registered
#7
I'm a bit confused on the topic of airstones; do you mean that you can safely use the kind that make bubbles in an octopus tank? I always provided a splash return and open sump for aeration, but I was wondering if such devices that I think you're suggesting are safe......
 

DWhatley

Cthulhu
Staff member
Moderator
#8
There is debate on using any kind of bubble making device and I have seen opposite reports (large vs small sized bubbles) that caused a problem with air getting trapped under the mantle.
 

Joe-Ceph

Haliphron Atlanticus
Supporter
#9
dwhatley;158778 said:
A spill proof lid will cause heat issues as well as air exchange problems...
But wait, he's going to splice this octo tank into a much larger existing system, so gas exchange and heat transfer will happen in the rest of the system, and this tank being covered or not will have minimal, if any, affect on the system as a whole. The water needs to be well oxygenated when it gets to the octo tank, so maybe put it first in line after the sump and/or skimmer, and make sure there's enough water cycling through per minute to more than keep up with the octo's breathing.

I just found a few pieces of my 2 year old's Sidewalk-Chalk at the bottom of the "clean" water jugs that store the water I buy for water changes. I found them AFTER the water change, so my bimac is now very familiar with the smell of Sidewalk-Chalk. I think it makes sense to design in some anti-kid measures.
 

Joe-Ceph

Haliphron Atlanticus
Supporter
#10
CaptFish;158726 said:
45 is really too small. plus The jury is still out on whether cubes provide any advantages or disadvantages with keeping octopuses.
A 60 cube (24 x 24 x 24) has the same footprint as the 45 he's considering, and so would fit where he wants (assuming it's not too tall). Wouldn't a tank that size be fine for an O. hummelincki? My bimac is happy in a 30 x 18 x 24, and hummelincki is a bit smaller than a bimac. I guess the problem is that you never quite know what species you're getting until you open the box, and if your "Hummelincki" is really a Vulgaris, then you've got housing issues.
 

DWhatley

Cthulhu
Staff member
Moderator
#12
A 45 would do (NOT A 35!) for MOST hummelincki and aculeatus. However, if you have followed along with the hummelincki's of late you will note the same thing that some of the scientists scratched their heads over, they don't have a "standard" size. With Penny, we almost wonder about natural cross breeding. Octane was in a 35 (that was SUPPOSED to be a 45 and not until he started to outgrow it did we measure it) and it was too small. We were cycling a larger tank for him when he died. On the other hand Maya was dwarf sized but still used the full length of the 65 gallon tank (where mercs are much less prone to traveling about). As anyone who has kept an octopus will tell you, you can't set up a system for a specific individual, they don't live as long as you are going to have the tank (and typically not much longer than the time it takes to properly cycle it) so it is best to set up a system that has enough flexibility to house several years of inhabitants.
 

Joe-Ceph

Haliphron Atlanticus
Supporter
#13
dwhatley;158937 said:
...As anyone who has kept an octopus will tell you, you can't set up a system for a specific individual, they don't live as long as you are going to have the tank (and typically not much longer than the time it takes to properly cycle it) so it is best to set up a system that has enough flexibility to house several years of inhabitants.
Good point. I sized my tank only for O. Bimaculoides because I can catch those myself indefinitely, but 99% of octopus keepers have to play species-roulette with suppliers, and so must be able to the largest species (and largest individual) they might get.
 

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