Hi, thanks for reply.
I'm not just starting out with a tank, I've had fish for years.
I have been testing the water daily, always before changes, and doing large water changes every other day since that first death started to look like an infection.
Results for am and nitrite always 0, nitrates never too high.
I feed lightly, 5 days out of 7.
They're not spiraling. They flick against plants and hide a lot, then lose the ability to swim. Another guppy seems inflicted now and his tail has started to disintergrate. I only did a large water change yesterday.
So far it's the gups and neons being affected only.
I have started treating with a broad spectrum med, I don't have carbon in the filter.
Confused about what's continuing to get them...