i had 1 in my tank also took me a couple of weeks to get it out. wait 2 to 3 hr. when your lights go out then check your tank. i used a flash light, now getting it out might be a problem if you see what rock he runs to you got him pull out the rock use some RODI water that's how a got mine out. if you cant find the rock yuo are going to have to set a trap for it i have ever done this