Can someone ID this hitch hiker?

[Sumfingwong]

Originally Posted by reefmaster12345

i hope soon befor it kills eny thing in your tank

Or I need to catch the mantis before he is a snack to my porcupine and dogface puffer (when they are big enough)

[Sumfingwong]

Saturday night, I can hear the clicking sounds from the mantis. So I decided to check out the tank after lights out.

I ended up seeing a black crab, a brown crab (gorilla I think) and 2 small blue crabs.. upon a closer look, I think they have fans on them. Are most fan crabs blue?