Koi solve mysterys too!
 

It was a rerun and I had it on my DVR for several weeks, but I was tickled
with the 'solution' of "Columbo Likes the Nightlife", I think it was called.
A new nightclub owner's partner dissapears. Columbo solves the mystery by
noticing that there are 2 large tanks of koi, in the floor, the same
dimensions, but one has half again as many koi. "Just one more thing sir. I
asked the director of the San Diego Zoo and he told me that because koi
produce waste products, which can be toxic, the number of fish must be
limited based on the volume of water . So why does one tank have 14 koi and
the other 9?" Because the culprit made one tank shallower and buried has
partner underneath it. So be careful before you nag your spouse TO DEATH,
about building a new pond:)
Bill