Welcome to TRT!!!
You are correct in that your
green brittle is probably the cause of disappearing fish. They are notorious predators, they "tent" themselves and drop down on unsuspecting fishes as they dart beneath them to hide.
Having said that, it's highly unlikely that the tiny brittles you are seeing in your tank are of the same specie. "Mini" stars are quite common and they are a welcome addition to reef tanks. They stay small, unlike their green cousins - biggest "wingspan" I've seen is about quarter-sized, most stay about dime-sized with body discs about the size of the head of a pin or slightly larger. These are wonderful detritivores and scavengers - let them be.
I would either sump that big brittle or find another home for it. Meanwhile, feed it well with pieces of clam or squid or krill and it is a bit less likely to dine on your piscine friends
HTH
Jenn
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LFS Owner:
Imagine Ocean

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