Ok so over the past few weeks I have been having real trouble keeping my pepperminnt shrimp alive. Ive been over and over the test and they always come out spot on. I thought at first that it was just a fluke but ive gone through 6 so far. I have hermit crabs and snails in the tank along with a clown and a bunch of corals that are all thriving. At first I thought it was my Royal gramma took him out and still 3 died. I got a Camal by mistake with my last purchase of a peppermint shrimp and hes doing really well. What is causing this? Please please help me.