DHyslop said:Water quality aside, wouldn't 700-800 gallons still be a little tight for a GPO? A former housemate of mine had a nice 125 setup. I'm imagining stacking 8 of those together and putting a critter in with a 12' armspan in. Sounds a little tight! I would assume that with a setup like this you would release the animal before it got too large (I don't know how a home aquarist would get it out and transport it!).
Is the 3000 gallon tank in Seattle the two connected vertical cylinders? Not knowing anything about GPOs personally, it seemed a little confining for the two they had in there when I was there last spring. But I don't know, maybe they aren't very active or exploratory when they're bigger?
I've moved this to a new thread with a more accurate subject line - At least I hope that's what I'm doing!
I probably should have emphasized this point more strongly in my earlier post: We only keep a GPO for one season which runs from about mid May to about mid September. At the end of our season the octo is returned to the wild so that it can go about its business of getting ready for breeding. BTW: We return them sooner if there's any sign that the individual is unhappy; There's a surprising amount of variation in this. Some GPO's readily accept captivity and 'enjoy' the lack of predators and easy food supply while others are obviously upset by the situation. A GPO that stays with us for the whole season usually weighs something between 10 and 20KG on release.
One aspect of captivity that the octo must accept is that of being handled. Our GPO is usually removed from its tank once per week so that the tank can be cleaned. In most cases the octo seems to regard this sort of thing with curiousity rather than distress and only rarely do they try to escape from their temporary quarters (20L pail). As an aside, we've never had a GPO try to bite a handler - OTOH Our other native species, Octopus rubescens, almost always trys to bite. When O. rubescens succeeds at biting it has a toxin that causes a pretty painful reaction.
As to tank size, our tank (about 3400L) probably is too small for a full grown GPO, which could easily be twice the size of the ones we release each year. OTOH: I'm not convinced that, water quality issues aside, overall tank volume is the main parameter to consider. Our tank is 183cm long X 152cm wide X 122cm deep (approx.) and I honestly believe that this doesn't cramp the animal much at all. If we were a more well-to-do facility I think we could get somewhat better results if the tank were somewhat shallower with a comensurately larger footprint. The main drawback to small volume tanks (