Lean it up against the rock you think he is in, i would set a couple 1 liter traps, my buddy caught his cleaner shrimp and hermits a bunch of times. But eventually he got the dreaded Mantis. Good luck.
50 Gallon Oceanic: 2 maxijet 1200's, 2 150 watt visitherm heaters, BakPak II Skimmer with PS & BT, Coralife Lunar 2X65 watt Power Compacts
Filtration: 50lbs LR
.com, 60lbs sand
Swimmers: 2 O. Clowns, Yellow Watchman, Firefish, Yellow Tang, Dottyback.
Clean-Up: Several snail & hermits, Skunk Cleaner, 2 Peps.
Corals: 2 zoo colonies, yellow polyps, star polyps