It moves

I brought these home in on a rock awhile back (lower left of the return) and see them in various parts of the tank. Is this a anemone, and if so is this a good guy? The LFS called them bad and said that they can get out of control.
tnx

 

Aiptasia Anemone and your LFS was right...they multiply quickly and can sting your corals. They aren't hard to get rid of, but if you get too many it will take longer than it needs to. I would nuke it with some Joe's Juice or Aiptasia-X, either are effective. Also, Peppermint Shrimp are supposed to eat them and bristle worms, although mine never did either and was eaten by several nassarius vibex during a molt.

Gin

 

I have never had any luck with anything but the p. shrimp. You have to make sure you do not get camel shrimp. They look almost identical, but c. shrimp do not eat aiptasia.

 

I got rid of a few small ones with some very hot water, boiled it for a bit(top off water, not tap) and then used a plastic syringe to blast them...some took two attempts but it killed them eventually

 

depending on the size of your tank, from the pic of the back wall I'm guessing it's some form of nano, I'd just get a few peppermint shrimp, not only will they eat the ones there (they should not all of them take to aptasia immediatly you have to nearly starve them sometimes) but they'll keep them from coming back via eating the new ones popping up while they are tiny, the only other thing I know of that eats them is australian copper banded butterflies, some say their non-reefsafe but I've never had an issue with them. As stated above make sure you get peppermint and not camelbacks though, camelbacks are non-reef safe shrimp and won't eat aptasia

 

Hard to say what kind of anemone it is from that picture really but regardless of what kind it is, I would get it out asap.

 

You need to be careful with the camel shrimp because they are not reef safe either...

 

Even some peppermint shrimp have been known to east zoanthids/mushrooms so be careful there to. Try some joes juice, id turn the pumps off and scrape that one off the back with a razor blade while someone siphoned it out.

 

Yes, it's a 12G and these are pretty small. I had 2 on my Coral rock that are smashed, hopefully they'll stay that way. I would rather smash or scrape them off than use other chemicals to possibly damage other things. Sounds like the P.Shrimp is the way to go, but I have an Emerald Crab that I fear might make shorter work of the shrimp than the shrimp of the aiptasia.. What to do..

 

Please do not smash or scrap them off, this will just end up multiplying them!