my shrimp are missing

I have a 150 gallon sw tank,have had my shrimp about 4 months got up this morning they are gone,red fire shrimp is missing and 3 of my mantis shrimp are gone, i have a percula clown,naked clown,and a diamond back goby and crabs and 3 turbo snails,in the tank,i also had a black clown in there he jumped out and died and also had a sand shifting goby jump out is it possible that the diamond back goby is taking over.if so i will get rid of him.

 

You kept 3 mantis together in a tank? That's usually pretty hard to do without them fighting and killing each other.

 

wow 3?? usually the quote is only put stuff in with a mantis if you don't want it to live.

 

My shrimp has been missing for about a month, I'm guessing he is dead!

 

Yep

My peppermint shrimp is missing too. For a few months now. I just found out the other day that my 5 inch hermit crab is the culprit. Now I am missing a urchin and there are no signs yet that he is the culprit but I am starting to wonder since the urchin's name was not hoodini.