It was popular in ancient China to raise goldfish in outdoor pools and water gardens, which people still do today. Goldfish were put on a show in indoors in small containers on special occasions, or when there was an incredibly beautiful specimen. Goldfish were formally bred and brought indoors during the Ming Dynasty around 1276 AD, attaining red, gold, spotted, and other colored fish.
Goldfish are omnivores in the wild, eating aquatic algae, frogs, newts, fish eggs, and larvae of insects. Pet goldfish do well with pellet fish food enriched with veggies, but some elegant varieties can require a good chunk of live food in their nutrition or risk gut issues. The primary reason so many goldfish die early is that they are not held in the right conditions.
Goldfish kept in a tank on average have the shortest lifetime at about five years. Goldfish can live up to 10 years indoors in an aquarium, whereas those kept outdoors in a freshwater or pond can live for at least 20 years, often for up to 30 or 40 years.
Goldfish live and sleep open-eyed. They simply don't have eyelids, so they won't be able to shut their eyes even though they wanted to. Goldfish were once thought to be a good fortune on the first wedding anniversary. It was practice for recently married people to give one to their wives.
Goldfish have no memories of three-seconds, despite popular belief. Probably, they can recall events that occurred up to three months ago, maybe more. Goldfish have a perception of habit and can be taught to do little tricks to release food, such as swimming through hurdles and pushing levers. A goldfish community is named "the disturbing one," not a school.