Need some urgent help! Fish covered with extra mucus, heavy breathing, and lying on the bottom of the tank once in a while. I'm listing out the timeline to see if this helps with the diagnosis. Left town for two days, and things went straight downhill with this fish.
Left town on Friday morning, and friends came to feed the fish two times every day. Saturday morning, a friend came for a water change and redose copper. I think I vaguely see Ich increase again on the fins from the video, but the fish looks happy still. This is also when copper has dropped again, I think, because when I came back home and tested today, copper was 1.75 ppm, so clearly my math wasn't correct when I told my friend how much to dose. Prazi should also be dropped since I have not redose. Last timestamp someone came over to my place and checked on the fish was 10 pm Saturday, says the fish looked active. I came back home around 3 pm today. The fish is lying flat on the bottom of the tank, so these symptoms developed in the past 17 hours.
My first suspicion was high ammonia and high phosphate, because I have a lot of algae growing on the tank glass. Not sure how much I can trust the API test, so I cleaned them up anyway in three batches and dosed copper, and changed water 30%, 40%, and 20% (last water change was because I noticed copper rising up to 2.70ppm, so I diluted with some new water). Seeing fish doing slightly better after changing the water since it was upright for a while. However, I just noticed it lies back down again.