Not sure how much detail was covered in-thread (rather than the article referenced) but I own two tube anemones myself.
Here are some considerations:
1) Size: This one's kinda important as one of the ones I have is rather large with tentacles extending over 12" at times. The other one I have is smaller, maybe 6" or so at most, (tentacle length). I have found sources that claim these animals routinely reach gigantic sizes in the wild.
2) Sand bed: A pretty deep one is a must! I had both of mine in my 55g with only a half inch bed and they weren't anywhere near as happy as they are now with a good 3"+ to bury themselves in. They love to burro and if your bed and or location is sufficient they will hide completely out of sight at times.
3) Clownfish: While I had a pink skunk clown in the 55g with two of these, I have read numerous sources which suggested caution should be used as a clown might mistake a tube anemone for a host anemone or a coral to host in.
4) Don't touch: This one should be obvious but I've run into enough people, (some of which worked at chain pet stores), who didn't know enough to NOT TOUCH an anemone with their bare hands let alone a tube anemone which have FAR stronger venom. Also, to take this point another way: You're not going to likely want to touch it much anyway, these have GOT to be the most creepy creatures I've ever had the misfortune of picking up. While a feather duster is relatively small and its tube is parchment-like and rigid, the tube anemone is a rather large worm and its tube is just a 'thin' skin over the worm itself... When you touch it it WILL move and as with my larger one, you're talking about a worm that's a good two inches around... that's just .. *EWWWW!*
5) Aggressive?: Many sources I checked claimed that these animals are VERY aggressive etc... Well, take this as you will. They don't move very much from my experience, so anything that they'd attack would have to get very close and contact one of the tentacles, so, I guess they're no more aggressive than any other anemone. However, if you feed them regularly, with mysis or krill you shouldn't have any issues with them going after anything. One thing to note though is that if a fish DOES stray too close they WILL get stung, and I've seen two of my fish wind up sea star food because of them. One Look down swam right into it and my box fish, after getting sick, drifted into the other one. Neither one fish survived for long afterwards.
6) Prone to Cyano: If you get one and it keeps a portion of its tube above the sand bed, watch it for cyano growth. My large one looks like it's bleeding from time to time as cyano tends to start growing on the side of its tube. Just thought it worth mentioning.
Beyond these, I really can't think of anything you might need to know about them... They are VERY beautiful animals especially ones with the fluorescent colors. My large one is a rather bland light caramel color the other, though, is very pink. If I get our camera to work I'll see if I can get photos up of them! Hope this helps!
