The Oranda Goldfish is characterized by a fleshy outgrowth on the top of its head and sides of its face, called a wen. They standardly have a dorsal fin, paired anal fins, can grow up to 12" or more, and survive in temperatures ranging from 65 - 78 °F, ph from 7 - 8 +, and are best fed a collection of fresh foods or hand made food due to the frequency of Flip-Over cases seen in these fish.
Due to the design of the wen, and the fact that it appears to grow in stages or bursts during the spring and fall season, they can be prone to bacterial infections and goldfish "pimples" on the wen. Most of the time they do not require any treatment, but if the lesion turns red or angry looking, steps should be taken to avoid infections.
Also, sometime the wen can overgrow the eyes of the fish, causing it to have limited or no vision. These fish should not be destroyed as they can still function without their eyesight. The wen can be trimmed, but most of the time it simply regrows.
A common fancy version of this fish is called the Red Cap Oranda(as shown in the picture). It is characterized by a solid white body with a "red" (orange is often called red for goldfish & koi) wen. Due the genetics of the coloring, if it often the case that Red Caps will lose their Red Caps as they age, becoming solid white fish.