Are you saying that the limit is set to exactly when fishes die en masse, so if we raise the limit by 0.0001 degree they will actually die en masse? Or did we

Are you saying that the limit is set to exactly when fishes die en masse, so if we raise the limit by 0.0001 degree they will actually die en masse? Or did we choose an arbitrary number that is lower than that limit, with some arbitrary margin?