Some "pollution" can actually increase fish production and size in the shortrun but in the longrun can have detrimental effects. Obviously manure etc. is a form of fertilizer.

However a pond vs. a larger body of water can only handle so much without problems regarding too much BOD etc.

A reservoir near me once had the fastest growing bluegills in the nation due to leaking septic tanks and some raw sewage. However eventually the lake became so fertile it worked against that, and became less hospitable to gamefish species and then carp became the primary fish produced.

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.