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[Octopus]: Starting my first octo tank!

Jun 16, 2015
Hello guys! First off, I wish to thank the runners of this website. Such a wealth of information and support, I feel very confident about this endeavor because of the work that has been put into this website. I haven't ordered the octopus yet, but a vendor I found through this website is going to get an Octopus Briareus for me. I have a 125 gal acrylic tank to house it in so that should be plenty of room with about a 1lb of rock per gallon. It has been running for about a year so it is well cycled. However, I did just move the tank and did a 75% water change a week ago. I have ordered 50 shore shrimp to arrive tomorrow to just have in the tank. I am hoping that this will make the octo comfortable as it can hunt whenever it wishes. If this isn't a good route to take let me know! The vendor stated that I will probably be getting an adult. I still need to seal off the tank, I will provide pictures. But for now I need to seal off the opening to my power head, the overflow and 2 dollar coin sized holes that are in the 2 lids sealing my tank. Was thinking about getting some heavy duty clamps and a small weight to keep the lids down. How strong are octos is this enough reinforcement for the top?
Aug 13, 2009
If the animal you receive is an adult O. Briareus, then you shouldn't need to cover most standard overflow grates. If the top of the overflow is open you can seal it with a large sponge, a piece of acrylic, mesh, egg crate,..the options are almost endless. As for live food in the tank, a few is alright, just don't go hog wild and over populate the tank. Sometimes having too high of a prey density can stress them out. I hope this helps.
Jun 16, 2015
Thank you! Well for now I'm gonna try and keep the 50 shrimp in the tank. I don't really have another option. Might give my roomie some for his reef tank to reduce the density in mine. Here are some pictures of my tank and the areas I'm gonna try and seal off shouldn't be too hard



Staff member
Sep 4, 2006
Nice looking den structures!

An adult O. briareus will need larger food than shore shrimp but I don't expect the shrimp to be a problem in the tank and they help keep it clean. The best food I find for briareus is thawed seafood counter frozen shrimp and blue crab claws (these I get when my local Asian market has live crabs. I pick out the loose claws from the bins and freeze them -- don't freeze a whole crab as the body will contaminate the meat).

For treats you can feed live fiddler crabs (or any other small crab -- I disable the claws of crabs that can puncture skin -- and an occasional crawfish. Crawfish tails are gladly accepted and can be frozen without the body but you can feed live. These are freshwater animals so if kept live they need their own container with freshwater and you need to be sure they are eaten within an hour -- remove them if they die in the tank.

You can also offer pieces of raw saltwater fish (avoid freshwater fish and ALL fish from a pet store - pet store fish are treated with copper and can be lethal to an octopus).

Clams are also on the menu (I keep live clams from the grocery in my octos tanks. Sometimes they get eaten and sometimes they are just cleanup crew. Soak them in an aerated bucket for a few hours in tank water to help eliminate waste and ensure they are alive. For an anticipated meal, you can offer them on the half shell and remove if not eaten overnight. Other mollusks can be offered as well but I find oysters and mussels to make a mess in the tank and avoid them.

O. briareus usually does well quickly with a feeding stick. Place the dead food on the stick (nylon or bamboo skewer) and hold it near the den. You may have to leave the stick for a bit as they often decide they want it too but will become bored with it in a short time.

Be sure you will be able to acclimate for about 3 hours when you receive it. O. briareus tends to be very slow to leave the acclimation container and I recommend NOT using a bag for the release. Instead encourage the animal into a plastic container (small critter keeper works well) or shell while acclimating and place the container into the tank.

We have a large number of journals for O. briareus. You can search the Journals forum by typing briareus as the search word and checking the title box for a list.

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