Amphipods won't harm a healthy zoa something else had to harm it first. But if it is a Isopod they will kill anything they can for food. They look like a Amphipod but larger.
This guy was pretty big. All curled up on the zoas it looked to be the size of a fully opened polyp if not larger. For I second I thought, "Why the **** is that zoa opened up that big at 5am?" and then I turned the lights on.
These zoas were perfectly healthy. They started as a frag of 3 and had grown into almost 7, until like two days ago, when I noticed a couple, like not there any more. I have seen zoas die, but this was strange, open big and bright one day to gone the next.
Ive done some searching and other people have had the same issue.
Sounds like just about every zoa I've ever tried to keep. Here one day, gone the next. Been trying to figure it out for a long time. I believe it has something to do with my small tank and water changes. Just to stressful for them. Any type of WC in my tank is major