Primarily, goldfish was known by Carassius auratus. Native to ancient China, it was the first fish to be domesticated over 2,000 years ago! Goldfish can recognize people's faces as they can differentiate between faces, shapes, colours and sound. Goldfish have no eyelids, so they have to sleep with their eyes open! The growth of goldfish can be stunted by controlling the size of aquarium, however, they can grow to over a foot long! The average breed of fancy goldfish can easily attain 6 to 8 inches or more. A round-shaped aquarium is dangerous for the health of your goldfish! Avoid floating food such as flakes. Goldfish can see more colours than humans! Goldfish don't have memories?