Ranchu are one breed with many color forms. Red-and-white is the classic show color in Japan; everything else came later, mostly from Chinese and Thai breeding programs.
The traditional show pattern. A red head with a white body, or red patches on white, is prized in Japan.
Solid orange-red, the most common and often the cheapest way into a well-shaped fish.
Velvety black that can fade toward bronze with age or warm water. Strong lines show well in top view.
Blue, orange, black and white on nacreous scales. Every fish is a one-off pattern.
Pure white or pearl. Shows the outline of the head and back with nothing to distract from it.
Slate to steel grey. Uncommon, and often sold young before the color settles.
Warm brown, sometimes with an orange belly. Popular in Thai lines.
The Chinese cousin: straighter back, bigger wen, tail held higher. Often mislabeled as ranchu in shops.
"Ranchu" now covers two quite different fish. Knowing which one you are buying tells you what shape to expect as it grows.
Bred for the tub and judged from above. Selected on the outline of head, back and tail. Lines are named for their breeders (Uno-kei is the best known) and prices climb steeply for show-quality fish.
Bred for the glass tank. Selected for a big hooded head, bright color and a fuller tail that looks good through the side. Most fish sold in Western shops and online are this type.