A week in the life of an octopus


New member
It's been a week since I received an octopus bimaculoide from fishsupply.com. And, I'm happy to report that she's doing well. She's always hungry and constantly roaming the tank. Very bold! She even tried to eat my finger once! Here are some of my observations.

She's by far the most interesting ceature I've had in a fish tank. Definitely very intelligent with almost mammalian behavior sometimes. When she wakes up in the morning, she would stretch her arms, rub her eyes! Sometimes, she would go behind a rock and peek from behind it at me. When hungry, she's very active, crusing the tank all day. It's very funny when she goes for a free swim, almost like a jelly fish.

Within a day of arrival, she's discovered all the hidden crabs in the rocks. She also ate crayfish with relish. Amazingly, she also attacks supermarket shrimp, and play tug of war with the stick that I use to feed her. (It's amazing how strong she is.) However, I'm not too impress by her hunting prowess, the damsel is still alive in the tank! Although I think it lives in fear. I've seen her methods of going after it. Just before dawn, she tries to go under the rock where the damsel sleeps and slowly creeps in. But her arms are not fast at all, the damsel easily slips away.

Color changes are quite frequent. Obviously, this is how they communicate. I just haven't figured out what the message is. The most interesting is when she turns half black and half white, down the middle like the joker. I've only seen that once.

Now for setup details. It's a 29G tank with liverock. The tank is run like a reef tank. No mechanical filtration. Occasionally, I'll run carbon. I use a prizm skimmer. (I'm not too impressed with it. Works like a bakpack. I still see a slick on the tank surface.) No sump. The tank is not heated. But the temperature is still around 77-79. This is too high. I have to figure out a way of lowering it. Tankmates are a royal tux urchin, a tigertail cucumber and the damsel. I'm planning on adding a sea star. She leave everything alone except for the damsel.

I say she but that's really a guess. I heard males have an arm that's slightly different. I can't see any differences in her arms. Her head is about 1.5 to 2in long. The arms are about 5in long. I have a suspicion that she's almost full grown. Does anyone have any idea how large a full grown bimaculoide is?
Ok, The males of most bottom living "benthic" octopuses have a modified third right arm.It has a channel like groove running along the lower edge. The special 3rd arm is known as a hectocotylus. It has a spoon like tip known as a ligula. Its hard to tell with out picking the octopus up and looking closely. But you may se it if it spreads against the glass in front of you.
As for size. A bimaculatus can have a arm length of about 80cm. A bimaculoides can have a arm length of about 35cm. So your little octo could grow to have a arm span of roughly 3 feet. In captivity they tend to get the size of a grapefruit balled up. Provided the tank is big enough and you feed them well.
Sounds like things are going well. Run your water through some good carbon incase the little squid inks. Not coconut carbon. The good stuff.
Thanks Cephalopoder for the useful info. I appears that a 29G tank is really too small. As it is now, she could almost touch the front and the back. However, cephsource claims that a bimac can be kept in 25-55 tanks. What's the real story here?

Since I've had her, she's grown some. I feed her every other day. So far, no tendency to escape. The tank is covered. But when I feed, sometimes she comes to the top. It's clear that she doesn't like to have arms out of the water. Nevertheless, precautions are taken.
A 29 is fine. I use a 30 for my bimac. A 29 is taller than a 30. Height is not as much a issue as is bottm area. A 30 just gives a little more room to roam. John Forsythe is co founder of ceph-source. He is one of the best there is on cephalopod behavior. He is a scientist at the NRCC. National Resource Center for Cephalopods. So if it says ok on ceph source it is ok.
More room is always nice for any animal and can let them grow bigger.
She is still doing very well. Although she has become increasingly bold. Last night, she's figured out how to pull the suction cups of power heads off the wall. She managed to pull a maxijet completely off! She has no fear of me at all. I'm constantly in fear if I stick my hand in. She thinks it's food and comes at me at all angles. So far, no bites. But I'm not about to find out what it's like. I think I'm not feeding enough. But since she's been in the tank for a short while, I'm worried about water quality. Therefore, I only give food every other day.

I've inspected her arm closely. I can't tell any difference. So, most like it's a female.
Thanks for the inquiry on the health of my little octopus. By now, she has established a very strict routine of sleeping during the day and begging for food after lights out. She has grown bigger and stronger, but thankfully also less restless. I think she enjoys the playtime we have during feedings. I do worry that I don't provide enough stimulation for this intelligent animal. Any ideas from you guys are welcome.
The stimulation thing has always seemed important to me also. I had my first octopus about ten years ago and I kept it in a college fraternity house. I always thought that had the advanatage of lots of visitors and activity. I have been concerned about just having an octopus tank in the basement and trying to rely on 10 minute a day visits.

Could you place a televison in front of the tank? :)

I put blue damsels in my tanks with octopus - because in the old days that is how the tank was cycled and I then left them in as an "emergency food source". My experience is that the octopus were either not interested, or unable to catch them. If your tank will support the biolad then they could add some stimulation (I have no idea). The little damsels are very daring and fun to watch as swim up to the octopus and venture close to death.
Hi everyone!
Just found this forum. Very interesting. Octopods are very intelligent and have very good vision. I would presume they do get somewhat bored as they are not out 'hunting' for food. I don't know what others think about it, but at the National Zoo's invertebrate house, the staff would place food into a glass jar with a screw off lid. The octopus was able to learn how to unscrew the jar to get the food out. Similar types of things are done with large parrots to keep them busy while getting food (placing nuts in holes drilled in wood), thus approximating their life in the wild spent hunting for food.

I think that if one is going to keep an intelligent animal in a smaller environment than its natural one, effort should be taken to stimulate it and I am glad to see people thinking about that. Maybe we can think of other interesting ways to offer food? The idea of giving whole clams and other shellfish is great because again it requires some work to eat as well as being a natural diet.

As an aside, I am happy to see that members promote having a large tank for these animals. Just because you can keep an animal ALIVE in a small tank, does not mean it should be done and that the animals is healthy. Humans could live in closets, but it would drive us crazy. :D
Sinbad, how is the "Lady" doing? I am still thinking about a tank for my work, I have a 38 gallon that I either want to be an eel or a cephalopod tank, any ideas