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Apr 30, 2007
Hello to all of you,

I have had a reef tank for a few years now, and although I am still learning stuff about that on a daily basis, I want to try an octo tank. I have a 40+/-gal octogon tank in the bedroom now. I have a blue devil damsel, and a tomato clown from hell in there. I have a few hermits, a snail, and a few zoos. I have crushed coral as my substrate. Roughly 30lbs of LR. I do not have room for a sump on this system.

I think I have figured out about my lighting. I am going to use the actinic that I used on a small reef for a while for the octos light. The only flow I have for now is just a skilter filter. Don't laugh it came with the free tank. The couple I got the tank from tried to keep an octo a few times. They could not escape proof the lid. I will make my own to know that it will work.

Is the crushed coral ok, or do I need sand?

Can I keep the two fish, or do I need to get rid of them so they don't mess with the octo? I hope he eats them.

Could I get away with using a Super Skimmer 65, and maybe a small MJ for added flow, or do they like lesser flow?

Is there a particular species that I should start with more than others now? The last one that I saw at the LFS, they couldn't tell me what it was, but they can oder different ones weekly they said.

Do I need to get rid of some of the rock? I have several large ones.

Any help would be awesome.
Crushed coral is notorious for becoming a nitrate factory and it is coarse, not easy on the octos skin.

Damsels are an absolute no-no, and Clowns being relatives of Damsels would also be a no-no. Any octo you could keep in a 40 (which isn't many) would just be bait. There aren't really any ideal fish, as they generally either become food or attack the octopus. Occasionally it works out, but I would only suggest seahorse friendly fish, and then still, there's no guarantee the octopus won't kill them. Starfish and urchins are the usual suggestion for tankmates, but avoid any carnivorous stars.

The Coralife skimmers are good. If you kept a regular weekly water change routine it would be fine. More flow is always better since it will decrease any dead spots in the tank, as long as the octopus can avoid the direct flow from the output.

Just avoid the mimics, wunderpuses, zebras... for a 40 gallon we wouldn't recommend anything other than maybe some dwarf O. mercatoris, maybe an Abdopus aculeatus. Those are small octopuses, the Abdopus isn't a dwarf but they stay considerably smaller than the other common octos. Really a 55 gallon would allow you more options. LFS's are notorious for misidentifying octopuses and giving them vague names. There are several places online that consistently sell certain species.

The more rock you have the better. More places to hide makes for a more comfortable octopus.
Where you said:
Can I keep the two fish, or do I need to get rid of them so they don't mess with the octo? I hope he eats them.

Fish aren't very good for protein I don't think, but if you want them to be eaten, leave them in and I bet they will be lol.
One of the major reasons fish are suggested as a major no-no is likely the same reason you call your clown, the tomato clown from hell, they are territorial and pick on anything that invades their space. Octopuses are soft bodied with delicate eyes and not much in the way of defense (in spite of the GPO drowning the the small sharks). They are clever but very vunerable and an aquarium increases their vunerability.
I figured if I have to take the crush coral, then the fish will come out as well. I might set up a little tank for my daughter and use that stuff for that.

I went from having to talk the wife into letting me get an octo for "her" tank, to her blowing me some crap because its not done yet. LOL