This is Ponds 101 and y'all probably already know it. I'm suspecting the water meal. Plants emit O2 in the daytime and suck it at night. Get 3 or 4 days of low sunlight via clouds and the plant life, including microscopic algae, keep sucking it. The bigger fish seem to go first from DO crashes.

It's not about the fish. It's about the pond. Take care of the pond and the fish will be fine. PB subscriber since before it was in color.

Without a sense of urgency, Nothing ever gets done.

Boy, if I say "sic em", you'd better look for something to bite. Sam Shelley Rancher and Farmer Muleshoe Texas 1892-1985 RIP