Koi & goldfish acting differently

Hi!

First, congrats if you are a ponder who hasn't been driven away from this
group by the late unpleasantness.

Second, my Koi and goldfish, about 12 in a 450 gallon pond, average length 6
", have recently been spending most of their time at the surface under the
fountain, They've pretty much stopped eating the tetra food sticks and
prefer to graze on the azolla that has grown on about 1/4 of the surface.

I've checked the chemistry, no ammonia, nitrates, salt at .05, ph at 7.4.
The fountain seems to put plenty of air into the pond. Temp is at 64. I grew
concerned when one fish died. Any ideas would be appreciated.

--
John M. Darnielle
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