I suspect the source of trouble was the older fish, which have spawned.
Most people, though, would rather put sugar water out than old fish.
Perhaps Jack hadn't always been such a old fish?
The story is told through the voice of an old fish speaking to her 12,000 children and grandchildren.
Most are in the 3-5 year class, but much older fish are also found.
The older such fish become, the more mercury they may have absorbed.
The air was rank with the smell of old fish.
True enough, but the remark hung in the air like the smell of old fish.
The older fish are not there at the rate we expect them.
In older and bigger fish the body color can turn to yellow/bronze.