There is nothing that can be done to cure the affected fish, but you really really really want to remove that fish from the rest of the tank. 1) the disease may be spreading already and 2) when the affected fish passes, the other fish may nibble on the corpse and therefore really increase the chance of spreading the disease
searching for "fish and dropsy" in google finds lots of pictures, but the scales sticking out like a pinecone is classic dropsy. Put the affected fish in a quarantine tank as soon as possible.