Bigger is better, but length vs girth?

[Jhawk]

Ok, so in about year+ I am intending on aquiring my first octopi pet, and for several months have been floating around on sites and gathering information to have an idea what to prepare for.

First thing I read up on was most of the commonly kept species pros and cons and decided on one of the following species, o. cyanea or o. vulgaris, but probably leaning to vulgaris for avaliability reasons.

Either one require a big tank, the smallest I saw for a vulgaris was 120-150g and not sure about cyanea, although it's bigger so do the math. Wanting to end up with a very happy octopus I plan on having something like a 180-220g tank, the only problem is...given 3 dimensions, there are a lot of possible combinations to achieve the desired size.

So some input on what height, length, and width make for a happy octopi.

I plan on more then taking my time and doing the appropriate research as I move on to the next step so on and so forth.

Thanks

[dwhatley]

I recently mentioned a similar point when someone asked about tank size for O. hummelincki. I found a couple of pictures I had posted on photobucket of the two vulgaris housed at MOTE (TONMOCON II) and you can get a feel for the tank size. This tank was minimal for the animals (it is unusual to keep two in a tank successfully but these had been living together in the wild and were never separated). I think height and length are the two most important tank aspects. Height being the most important for octos that crawl with length being more important if they tend to swim. You can see my reflection in the picture below. I am relatively tall and my guess is the tank is over 3 feet tall but under 4 foot (my reef is 3 feet high and is close to the size shown in the reflection). I tried to get the gallonage of this tank but did not get an answer. I also think that the tank could not be smaller if only one vulgaris was housed there.

[Jhawk]

So maybe something like...

30" wide
40" long
40" tall

Which would be around 200-210g

[octokidwriter]

(it is unusual to keep two in a tank successfully but these had been living together in the wild and were never separated).

i thought that is was impossible for octopuses to live together at all. are/were they exceptions to the rule?

[monty]

Not impossible, but we advise against it, with the possible exception of dwarf siblings raised together in a large tank. A lot of the rest of the time, the octos will fight (sometimes to the death) or be very stressed out. In the wild, octos tend to be solitary; the MOTE folks didn't know why they got 2 friendly octos caught in one pot, but they seem to get along for some reason.

[Neogonodactylus]

There are several variables that you want to consider when selecting size and shape of an aquarium for octopus. The first and probably most inportant is whether it will fit conveniently in the space that you have. Consider floor loading, stand height, ease of access for routine maintenance, etc. A tall tank on a tall stand can be a real pain to maintain.

That said, the more water, the better because it will provide more stability to the system.

As for shape, that depends on the species of octopus. Many reef species such a O. cyanea live in 3-D and like to move up and down as well as around the aquarium. Other species, particularly those that live in sand move mostly over the bottom and you want lots of surface area.

Roy

[dwhatley]

Roy,
I have a question about repair vs regeneration. I have an octopus that lost 4 arms before becoming an aquarium pet. Three are in various stages of growing back normally. One, however, looks as if it had been damaged with only the tip actually having been removed. There are no suckers at all on better than half of the arm but roughly one inch of the tip looks like a normal regeneration. The suckerless section between the normal tip and the head is very skinny but I don't see obvious signs of scarring and he seems to be able to control the color. Can you make an educated guess on if a damaged arm will simply repair itself but not regenerate suckers and girth or is this more likely a malformation or failed regrowth?
Thanks

[Neogonodactylus]

I don't know how educated it is, but my guesses would be either 1) the arm had been previously damaged and was regenerating only to be damaged again or 2) the regeneration is abnormal. Personally, it sounds to me like multiple regeneration attempts.

Roy

[Animal Mother]

Kalypso's damaged arm now has teeny tiny suckers on the still-stumpy end...

Those dimensions sound pretty good Jhawk. The height might be a problem though. Dunno how a tank that high would be braced or how thick the glass would be.

[dwhatley]

Kalypso's damaged arm now has teeny tiny suckers on the still-stumpy end...

That is how Octane's arm started like and what I call suckered string. OhToo has three arms that look like that and I expect normal regrowth (Octane's arm grew back normally, eventually it widened to match the base as well as grew longer). It is the fourth arm that looks abnormal with normal growth at the tip but no suckers at all for half the regrowth length.

[Joe-Ceph]

There are a couple of side effects of tank depth that you may want to consider. The depth of the tank determines the thickness of the glass (or acrylic, or plywood, etc) that must be used to constuct it. The pressure at the bottom of a 40" tank is double that of a 20" deep tank, and so the glass (for example) must be twice as thick in order to be strong enough to hold back water at that high pressure. Thicker tanks cost a lot more, and weigh a lot more, so just be aware that there is a significant cost associated with depth. You might be able to get away with 1/2" glass for 40" deep, but that might be too thin (ask an expert - but be sure they know what they are doing, or you could have a very wet living room)

Also, I would hate to have a tank that was deeper than my arms are long because I couldn't reach the bottom, or most of the rocks. If you have a maintenance plan that doesn't involve SCUBA gear, then maybe you don't need to worry about it, but I hesitate to build a tank with places I can't reach.

[dwhatley]

Joe-Ceph brings up points that really hit home with my reef. I have a 2' reach and the tank is 3' tall. If I had it to do over, I would probably have gone with 2.5'. That still leaves .5' unreachable but it would be 6" down from the ceiling (I would not change the stand height because the minimal sump just fits and contains the skimmer) and I could have had a 6" taller canopy (more tank top to ceiling room), allowing easier access with cleaning tools for the unreachable parts. I would also recommend (as with my tall tank) a pentagon shape with black back walls if you have an available corner. This minimizes the clear surface that needs cleaning but does not take away from the viewing area (photography is impacted, however). Lastly, if you are going this large, acrylic is more suitable (and expensive) than glass (IMO) for its strength, weight and minimal likelyhood of ever leaking (assuming no leaks after manufacture). It WILL scratch and limits what you use for cleaning (scratch repair is possible but not very practical while the tank is in operation and is a major undertaking when the tank is empty).