Forgot to mention do your homework on them if they go wrong they can easily nuke a tank.
When buying the anenomie check.
Colouration.....make sure it's not bleached.
Mouth... Make sure it's not sagging
Foot... Make sure it's foot is good with no damage if the one you are looking at in the LFS is attached to a rock a safer bet would be buy the rock with it but check for things like aptasia and hitchikers.
If the LFS offers to remove it from the rock and they simply go to pull it off walk away as that will more then likely damage it's foot and they clearly don't know how to remove them correctly.
To remove an anenomie from a rock correctly you should aim a powerhead or a pump output at it this will make the anenomie moody and it will slowly release it's own foot from the rock as it will want to move from that environment you will then be able to get it easy.
Placement in your tank should offer the BTA some nice deep crevices in rock work for it to put it's foot in and feel safe a unhappy anenomie will tend to wonder.
I have had to move my rocks several times and both times I've had to remove the anenomie from the rock using the method as mentioned above so I could safely work on the rock work without any danger of me hurting him.
Both times I have built him a cave and turning him over to make sure his foot is clean of substrate and the area he is being placed free of substrate i laid him in the cave. He will then find the spot he like you will not force a BTA to stay anywhere it does not want to be. Provide a BTA with everything it needs and it will stay put and be very happy.
Hope that helps and is bassed on my own personal experience with them
