I had a manitis, I would recommend moving the last LR you put in to a place where you could view any caves, watch your tank closely for those creepy buggy eyes, once you have identified the den pull the rock in the morning and use a turkey baster with hot fresh water over a tuperware and start pumping in the fresh water, go for at least 30 minutes, when I caught the one in my tank it took four fully loaded turkey basters before it came out, they are super tough. Once you get it out of there keep it in a tuperware with an airstone and some water from you tank, post a pic online, lots of people want them for species only tanks, don't kill it unless you can't get somebody to take it and cover your shipping charges etc, they are a cool animal if you can have a species only tank.
Just my 2 cents!
-Jason
