Finally caught that *******. You need a plastic baby bottle complete with nipple. Drill a few very small holes in the bottle so air escapes when you put it in the tank. Cut a tiny hole in the nipple and then cut a 1/2" slit lenghtwise in the nipple (from tip toward base). Put some sand in the bottle so it doesn't float and bait it. I used clam because I figured he was tired of shrimp having eaten 2 in the last month. Put the nipple on facing into the bottle and put it on the substrate. After over a month trying every suggestion I could find ,this trap caught the (expletive deleted)in 24 hrs. BTW, this my own invention and will be available at a website near you for only $110 + S&H That's the cost of fish and shrimp the little devil killed in 2 mo.