I don't have a nitrate test I'm far to broke to afford anything more for now. I trust this guy, if something wasn't right on the nitrate he'd tell me. The problem is persisting. The gills are still crazy red, but the fish are acting normal, no sign of the water parameters being off, like they aren't acting like there is a problem with the water. I don't think it's the water... anything else that could cause red inflamed gills?