I introduced my pistol long before I found a healthy yasha goby at my LFS. Maybe 6 months my pistol shrimp was in the tank before I added a goby. I put fish in on the same side of tank thy shrimps burrow was. The goby Didn't even see the shrimp and with in seconds the yasha goby as in the burrow. Unfortunately I havnt seen my goby in 2 months. I still hold out hope since he has gone missing in past and I found in the sump.