Ok here goes - sorry to hear about the mandarin - look like you have to hunt that pistol shrimp even if you have to use a pistol yourself! It needs to come out buddy before it starts going after others - I stand to correction but these shrimps dont even have to battle with their prey they just "click" their claws and that split second is what actually is the shooting of their prey - the cracking noises one hears outside the tank and its over - it like stuns the prey then they attack - but happens very very fast - once again sorry bud - plz get rid of it....