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Octo behavior change


Jul 22, 2006
All -

My bimac has undergone a serious behavior change that has me very concerned. I have had her for about three months, for most of which she has been a voracious eater and has grown to perhaps twice the size she was when I got her.

A few weeks ago there was a strong nitrate spike in her tank. I got it under control with water changes but since then her behavior has changed drastically. She made a new cave for herself under a large rock (partly because she no longer fit in her old favorite haunt), and no longer comes out to roam around. She cleared the area in front of the cave and any food I put there just gets pushed away. She has not eaten anything but small ghost shrimp in over a week. She no longer seems to accept live clams, fresh shrimp, or fish. She will taste them and then push them away.

I put a coral banded shrimp in there but again, she just pushed it away when it came close. I have not tried crabs as they are difficult to get around here (except for either miniscule emerald or hermit crabs, or giant-sized blue or dungeness crabs). I may try to go scrounge some up from a local beach.

I'm worried! Any ideas?




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First, :welcome: Second, sounds like your octopus is preparing for pending motherhood. Unfortunately the "denning" behavior is what they do along with the refusal of food. From looking at her pic are you sure she's a bimac? She has the classic coloring of the tropical octopuses and unfortunately the name escapes me but if you look at my posts under Egor, she looks just like her species. Keep offering food, as I've also had the exception to the no eating rule where Ink continued to eat several weeks after her eggs disapeared. Best of luck!

Thanks Carol -

Regarding whether she is a bimac: as you suggest she was actually advertised as an Atlantic species. However I had read an account from another person (James Wood) that he had actually received a bimac from them (saltwaterfish.com).

Also, she is of an appropriate size for a bimac (mantle size perhaps 2.5"), and she has the false eyespots (which appeared perhaps a month ago and are now always present). Would those be seen in a Caribbean species?

The sort of sea-green color shown in the picture I took this morning seems to be her default 'at rest' coloration. When on the move at night she normally makes herself dark brown. When moving during the day her color and texture will vary with her surroundings.

Hi and welcome to TONMO.com! :welcome:

I think Carol's on the right track about the denning behavior and perparing to lay eggs. And she gave you good advice about continuing to offer food.

As for the nitrate spike, I image it's only coincidence that this behavior happened afterwards.

The description of your octod doesn't really sound like a bimac. They're not the only species with eyespots. Also, a bimac's eyespots are apparent at a very young age. A bimac often has the spotted coloration (including some yellow) which you see in the photo at the top of the home page, to the right of the logo. That's Ollie, my bimac,now deceased. You might also look at the Bimac Care Sheet
Cephalopod Care
for more bimac photos.

Thanks Nancy -

I looked at the care sheet and I can say that she (Esther) definitely does not have the blue chain in the eye spots. In fact she seems to exactly fit the description and photos of O. Briareus, and this would also explain her small size and quick maturity.

Alas! It's the natural way, but I'm still sad. Life is too short!
It's confirmed! I saw the eggs. They are beautiful. My wife says they look like stars.

I don't suppose they could have been fertilized 3 months ago?

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