New (third) owner of this boat. Noticed a rancid smell last summer and discovered the fishbox was filled with what looked like blood/water mix. Totally noxious. None of the switches on the dash seemed to drain it, so I bailed by hand. Smell *almost* went away for a while. By the end of the season it was back and the fishbox had filled again (?!). Asked the mechanic at my winter storage to look at it and he said he 'unclogged the drain and flushed it out." OK. Everything seemed fine for a few weeks this summer but yesterday ... it's back. The smell that is. Opened the fishbox and, you guessed it, filled with slightly-less-bloody-but-still-pink-hued-water. WTF?

What could be going on here? Seems to me there are two issues: (i) why isn't is draining? and (ii) why does it fill back up? Perhaps they're related? Any suggestions as to where to start and what I can look at to begin to figure it out?

Many thanks for any advice. Dave