Gas leaking from middle stern below drain plug

[thunderbug]

Alright, this is kind of a scary thread for us novice rebuilders. Mine is an '88 Fisherman that has been sitting for awhile; is there an easy way to check the tank for leaks, other than filling it? I'm pretty sure it's the original and I've already decided to replace the hoses. And my "tank compartment" does drain into the bilge, right under the live well.