Pond Boss Forums INTRO Questions & Observations My minnows are dying

I have a 1 yr old, 1/5 acre pond. I have some structure in the pond for spawning. I have had thousands of FHM in the pond. We have had a couple of big rains lately, including a 10.25" rain in 24 hours. The pond ran over (a bunch). I saw a few minnows out in the pasture, and saw a few dying. They would spin in a tight circle in one spot, similar to whirling disease in trout. I recently added 20 BCs and 12 HSBs. I have not seen the HSBs since I put them in, but I think they are still there. Now, my numbers of minnows is low. I see quite a few small fry, but for average size minnows I probably only see a few dozen, maybe a hundred minnows.
Should I test my water before I add more FHMs, or, since some are still ok, just add them? There is no way the BCs, CCs and HSB have eaten all those minnows in a few weeks.
I appreciate the feedback.
BB

They can die from exhaustion and old age during the spawning season, they only live a year or so. I saw this in my pond. I had no predators, with predators I would expect them to be picked off pretty quick and not getting much of a chance to see them unless your population is that large. That's just one possibility of many

An overflow will take a lot of small fish. However, they have to be in that area. I expect you lost some but should still have plenty. They do a lot of spawning if you have the proper "stuff" for them to adhere the eggs to.

I do not think this is anything with their normal life cycle. Two weeks ago I had minnows I could walk on, literally clouds of minnows on every pellet put out, to now, 2/3 of the pellets float to shore unmolested. My wife found a dead CC (about 3.5 Lbs) behind the pond today, either a GBH or racoon got it. Buzzards were finishing it up when she saw it.
Not sure if the rain was cold and shocked them, or something was in the runoff. My aerobic Septic system is up hill from the pond, some of that could have gotten in, but not much compared to total rain. I still see some of the CCs in the pond, and some of the new BC.
I am just hesitant to put more FHMs in until I know what is happening.
BB

It could be as simple as the water being too hot for the fish to feed well right now. Hot water holds less oxygen also...