A lot of miss information there. A bubble tip anemone will not eat healthy fish normally. They do not knock over things unless they are not attached in any way.
BTAs generally move when they are going to split or unhappy for some reason. If you place a anemone so it can attach its foot under a rock or a hole in a rock where it can reach out to get plenty of light, but retract when it feels threatened, has good flow around it but not blasting it too hard, and your tank parameters are good they will often stay in the same place for years. If your lighting is inadequate or parameters get to far off it is going to look for a new home. If bad enough it will detach completely to let the currents carry if to a better environment hopefully. In our tanks that is when they end up in power heads typically!
