I have recently discovered a 2"+ ugly Mantis Shrimp in my reef tank and he's eating my hermits and snails. I bought this stupid trap and all I did was catch my good shrimp and hermit crabs. My choices are running out of options. My reef was professionally designed and I hate to think about taking it down but if there is no other way then that is what I'll do. I don't know of any predator that just eats mantis shrimps without killing my good ones. If anybody out there has any constructive ideas let me know. Thanks.