Have a guppy in a quarantine tank. It has fin rot and now it has red dots on body. It came out of a 20 gallon tank with .5 ppm ammonia and it has been having fin rot for a few days. What could the red spots that just formed today signify?
Probably a dumb question but your quarantine tank is cycled yes?
It could be from ammonia poisoning or nitrate poisoning from the other tank.
It looks raised around the mouth and that's why I suggested an injury first.