important fish problems HELP!

Question
hi i need help ok.
look i have a fish which woke up in the morning and had kind of big red round thing on his fin and a swelling eye.
i have no idea what it is and i am frightened it can affect the other fish in the aquarium, and that maybe it is a serious fish disease.
so does it affect the other fish in the tank, is this illness sever, and please send back the medicine i should buy for him
please reply fast
thank you

Answer
Sounds like a possible mixture between popeye and something else. Go to a pet store, find the fish medication section, and look for a brand called Mardel. They have a medication for everything, including popeye. It will show pictures on each box with names so you know what you're treating for.