Elephant Ear Mushroom = Fish Killer???

[Carmen]

I purchased this Giant Mushroom from a fellow reefer. He was not sure exactly what this mushroom was and it was sold to him as a Giant Creeping Mushroom. I believe it is actually an Elephant Ear Mushroom of some type and have read that they have a potential to capture and kill fish. Anyone have any experiences with this variety? Should I be worried about my fish??
This mushroom is atleast 10 inches long with 5 mouths and a green blue color.