HELP something is killing my fish

[raisin]

i need help something is killing my fish i have lost my pearlyjaws, a green madreine a blue madreine a i think a few fire fish i just seen a sally light foot crab that must of came out of my rock i have nothing but seahorses, pipefish, every thing that can go with them my water is fine i am going crazy anyone know what is going on ????

 

[newreefers]

Post all of your water params, and also check the tank at night with a red light, you may have a bad hitchhiker. (crab, mantis or something along these lines). What condition are the fish in when you find them dead?