Q. There is a problem with a mantis shrimp in my tank. I’ve lost several fish to this shrimp, but can’t figure out what to do about it. Do you have any suggestions?
A. Well, you aren’t the only reef aquarist who has trouble keeping fish in a reef tank due to the predatory nature of a resident mantis shrimp. You went on in your letter to note that you’ve tried trapping it at several different times of the day, but without any success.
Mantis shrimp are very wary animals. If you are trying to trap a mantis shrimp, you must allow it to get used to the presence of the trap by placing it in the tank and leaving it there for several days, or even weeks, before baiting it. When baited, the trap must be placed in the tank and left overnight. Keep resetting the trap as often as is necessary to capture the shrimp.
The trap should be a flow-through design so that the scent of the bait (usually pieces of raw tiger shrimp) can easily spread through the aquarium. A piece of PVC pipe with mesh sealing off one end, and a piece of mesh inserted in the other in the shape of a cone, usually works well. The smaller opening of the mesh cone is inserted in the PVC pipe, and should be just large enough so the mantis shrimp can barely squeeze through. This will make it harder to get out.
One final tip: Drill a small hole in one end of the pipe so that a piece of thread can be attached. This will make it easier to pull out the trap.