• Looking to buy a cephalopod? Check out Tomh's Cephs Forum, and this post in particular shares important info about our policies as it relates to responsible ceph-keeping.

Cycling a Cephalopod Tank


Staff member
Moderator (Staff)
Sep 4, 2006
Cape Coral, FL
We see more and more keepers that are not yet experienced marine hobbyists and want to begin with their new hobby with either cuttlefish or an octopus. While this is not recommended it is our goal to provide as much information as we can to help the journey be successful. The first step is acquiring what Thales calls a saltwater thumb and it begins with learning how to cycle a tank and understanding how a tank matures. To that end I will try to collect articles here for those that will be successful to ingest :grin:

I'll start with current posted references but hope to go back and find some of the other scattered among the posts. Feel free to add article references below with a note on why you like the approach. I will post the article link in this initial post but leave the original comment as it was written.

Starting Your First FO or FOWLR Marine System - Reef Santuary, member leebca, via TMoct
The Mature Aquarium - Reef Santuary, member leebca via TMoct
From TMoct's tank build out thread:

I'll essentially use the following recipes for "maturing" the tank, with modifications for an octopus tank (not introducing fish, etc.):

new reefsanctuary link

I like those two descriptions of tank preparation because they are very thorough, and also make it clear that "cycling" the tank is only the first of two major steps, and that the tank needs to be "matured" after cycling.
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Just curious- what is the recommended sump size per tank gallon that would be best for an octopus tank? I'm planning 30 gal beginner dwarf octopus down the road and was suggested to purchase a biocube and upside the sump.
Question about purchasing a used aquarium. I know that any heavy metals, especially copper, are a no go for inverts. I've read that there are conditioners that can lift them from the tank to clean it. Does this work so I can clean a used tank and then start to cycle it and get it ready for my octo(with a several month wait to get the water right for it). Thanks.

Also, just curious. Not the section for it, but I figure people here know things. Why do octos not munch on sea hares? or maybe they do but not at the same rate as their other tank buddies? Was just wondering if anyone knew.

Oh, and for sumps... are there some that work better than others for preventing escape? I've been reading up on them, but want to make sure I don't purchase one that is an octo escape hatch.
That is all--- for now.
I have purchased used aquariums but only if they were previously used for corals or could talk to the original owner to validate that no copper treatments were ever used. There is a high possibility that an acrylic tank can be successfully cleaned but anecdotal evidence that any siliconed tank can leach copper long after its initial use. The precaution applies to corals as well as a number of inverts but cephalopods seem to be the most susceptible to traces of copper not detected by aquarium kits.

I don't quite understand your question about escape proofing a sump. A sump is usually an external tank that is gravity fed from the main display (ie it sits below the main display tank). Getting water to and from the sump is where octoproofing is a concern but not with the sump itself. My recommendation is to have the display tank drilled (with a large tank, two exit bulkheads are recommended) with the bulkhead (hole and fitting) surrounded by a weir (overflow box) that can then be further octoproofed with a sponge and/or strainer. An additional bulkhead and some kind of screening is needed for the returning water (one of my hatchlings actually lived inside the return fitting until he was too large for the holes drilled into the pipe) .

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