Oranda
A variant of Goldfish (Carassius auratus)
A round twin-tailed fancy crowned by a raspberry-like fleshy headgrowth (wen); the Red Cap is a white body with a red wen.
Keeper tips for this variant
The wen can overgrow the eyes and traps debris — keep pristine water (low ammonia/nitrate) to prevent wen infections and watch that it doesn't blind the fish.