How to Find and Kill Evil Hitchhikers

[Pier Pressure]

Last weekend when the tank lights went out at eleven, all fish, inverts and corals were doing fine. The fish were eating like pigs as usual, very active.

By nine-thirty the next morning, five of my fish and three of my shrimp were dead. Now you may start thinking water quality, but the inverts, anemones, etc. are fine and water tests are good, too.

A couple days later, my firefish came out of hiding in the rocks. He is still very skittish but spending more time outside of his rock than he was originally.

Long story short - I think I may have a hitchhiker(s) that is evil and killing my livestock. How do I catch it/them? Especially if there is more than one.

The tank is only a 28 gallon but there are about 30 pounds of live rock in there. Tips or tricks most appreciated.