I added berghia and now I can't find them. Are they dead?
Probably not. Berghia are tiny, they hide in the rockwork, and they do most of their hunting at night, so it's normal to barely see them after the first day. The better sign is your aiptasia. If the aiptasia are shrinking or disappearing, your berghia are alive and eating.
What happened in our 16 gallon
About six months ago, we had about six aiptasia in our 16 gallon tank. Six doesn't sound like a lot (until they're in your tank, and then it's six too many). We added four berghia, two large and two medium. At the time, we didn't know much yet about how berghia work as a team.
We watched them the first night. And then... we never saw them again. Not once.
But the aiptasia started disappearing. One by one, they were just gone, and the whole thing took about a week. We haven't seen a single aiptasia in that tank since.
At one point I even spotted an egg spiral, which is the little coil of eggs berghia lay. That was the best news, because it meant at least one of them was alive and healthy enough to breed. I don't think it ever hatched, though. That tank has a lot of hermit crabs, and I'm pretty sure they ate it. (Rude.)
Who else lives in that tank
If you're worried your tankmates are the reason you can't find your berghia, here's who was in ours: two clownfish, a firefish, a goby, pistol shrimp, and a whole crew of hermit crabs and snails. I can't tell you exactly what happened to each berghia, because I never saw them. What I can tell you is that the aiptasia disappeared with all of those animals in the tank.
What we'd tell you if you're staring at your tank right now
- Watch the aiptasia, not the berghia. Pick one or two aiptasia you can see easily and check on them every day. If they're shrinking or gone, your berghia are working.
- Give it some time. Ours took about a week for six aiptasia. A tank with a lot more aiptasia will probably take longer.
What we still don't know
Berghia only eat aiptasia, so once the aiptasia are gone, they run out of food. We never saw ours again, so we can't tell you what happened to them after that. It's one of the things we're learning now that we're breeding berghia ourselves, and we'll write about it when we know more.
Still deciding how to deal with your aiptasia? Read how to get rid of aiptasia (what we tried, what we skipped, and what worked).