The full therapeutic dosage can cause her to stop eating and can account for her sudden “floppy” behavior.
I would completely remove the copper ASAP and get her eating first (soak garlic in food to entice the fish). Give her a couple of days to rebound and then slowly ramp up copper to therapeutic levels over the span of 5-7 days. Add an aerator as well.
I use chelated copper and always dose in the mornings so I can monitor the ramp up effects on the fish rather than dosing at night and praying the fish is still alive when I wake up.
Removing the sand and rock can also help maintain stable copper levels.
I agree. Do a large water change and run carbon to get the copper out. Once they start behaving normally and eating slowly raise it again.
Also remember you can NOT use any ammonia reducers like prime or amquel with copper.