Make sense Ion as oxygen is vital and I guess the NH4 or is the NH3 (cannot remember, no longer play with fish) would have really risen in the water due to the amount of fish and lack of oxygen and fish wastes.
"In Redondo Beach, dead fish, perhaps millions of them, collect in King Harbor Redondo Beach's King Harbor is inundated with dead fish. Experts believe the sardines sought safe harbor from a storm, but consumed the oxygen in their small refuge."
