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O. mercatoris setup and filtration plus egg rearing

Aug 9, 2006
Is 29 gallons two small for O. mercatoris? Or could I even decrease the gallonage? From what I have read a wet/dry filter is reccomended for large octo species, but are these neccessary for the dwarf species? Would a good canister filter plus LR be enough filtration? How many inches of sand should I have for a dwarf octo? Would fiddler crabs be too large for an adult?

How do you go about rasing the eggs? What equiptment and set-up should be provided?
Pygmy and dwarf species can be either large or small egged and for many of them we don't have any information.

O. mercatoris, or at least what is being called O. mercatoris coming out of the Gulf, is a large egged species that has non-planktonic hatchlings that are fairly easy to rear provided that you have live food and can isolate them to avoid cannibalism. The animals that come from Tampa Bay and the Florida panhandle breed seasonally. You will generally only find sexually mature females in the early spring.

We keep adult O. mercatoris in small tanks with canister filters and as long as you watch the water quality and do partial water changes, they do quite well. A 10-12 gal system seems adequate.

the size of the tank sounds good.

I could be wrong about O. Mercatoris [can't say I know much about them], but I've always thought that all species of octopi are cannibalistic. If you were planning on keeping two in the same tank, I'd think there was a possiblity of one eating the other, especially in small quarters....Just y opinion, someone else, feel free to chime in!
Yes, mercatoris requires a different temperature - bimacs are not from tropical waters and require a cooler water temperature. We advise not above the lower seventies for bimacs, but they live longer in even cooler temperatures, in the 60's. You can keep a mercatoris at 78 degrees - you may need a heater, but no expensive chiller.

Also, mercatoris are nocturnal, so you might want some red LED "moonlights".

The pH would be the same - natural seawater is 8.2.

29 gallons will be fine. I have mine in a 20 gallon. You dont have to have a wet dry. I use the filters that hang on the back of the tank. They do fine. However, a wet dry will always be better. I have a lot of dawrfs for sale. Contact me.

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