my friend has a comet in a 75g with a pleco. the comet has developed a red spot on its head. does anyone know what this is and how to treat it? also what kind of pleco is that?
As for the goldfish, it seems to be an ammonia burn. You should check the water and see if your ammonia, nitrite and nitrate levels are not within toxic levels.
add non-iodine salt after 30-50% water change with Prime water conditioner, and i hope it's not from the Pleco sucking on the gold fish cause they will sometimes do that when Pleco's don't have enough veg matter in their diet.
Most Goldfish keepers bock at the thought of a pleco with Goldfish . Due to the damage a Plec can do to one.. We must remember their teeth hold them to rocks in sometimes VERy fast and strong currents in the rivers