Considering your water temperature is 75/76F, your pH is 7.5 and your measured ammonia is 0.1, your NH3 (unionized toxic ammonia), by my calculations would be about 0.002 mg/l.
Considering your test kits ability (tolerance), even a high end reading of, 78/7.8/0.25 would only calculate to a 0.009 NH3 concentration. Both below levels toxic to most fish (0.05 mg/l). However, this is only a snapshot in time.
Unfortunately you cannot measure Dissolved Oxygen, which would be another wildcard in your water quality. Are your fish lethargic? Laying on the pond bottom with clamped fins, or gasping at the water surface?
You can take a fresh dead fish and look for gill color and blood color. Red/Lavender gills may indicate high NH3 and brown blood would indicate high nitrates. Also, fraying of the fins, which I see in your last photo is a sign of high ammonia.
I have an aerator running for the last couple days. Since I started running it, I'm loosing a few less fish a day. Don't know if that is the reason or I just have fewer sick fish left. My water is muddy. Can only see about 10in deep. The pond is new and I just built a house next to it with no lawn yet. Still doing dirt work to fix the yard. I just spread hay where most of my run off goes into the pond. I do have grass starting to come up around the pond. 2 sides of the pond has thick clover food plots around it and the other is the dam. It's just the one side facing my yard that contributes to the mud. So with that said, I can't see my fish unless one comes to the surface. I see the FHM schools all the time. I put a jar of pond water in a dark place yesterday. My pond has always been muddy. Took a long time (8 months) to fill especially with the leak. Lots of up and down in water level until I fixed the leak in March. Then added another dose of soil floc 3 days before I stocked it April 24.
I've been reading up on clearing the water.
