I have one and the only shrimp I had vanish were my sexy shrimp...but it could have been anything that vanished them (I only had 2). I have peppermint shrimp and they are fine. Pistol shrimp will eat shrimp that are smaller than they are and if the shrimp venture into the pistol shrimp area. I have had my pistol for about a year and a half and he lives with my yellow watchman goby...I will tell you, if you have a big tank...you will hardly ever see the pistol shrimp as it likes to burrow in the sand under the rocks. I had mine in a 30g and I could see it almost every night when I fed, but now he is in a 75g and I have not seen him in a month...lol! You will hear them though (click their claw), it is a loud pop.