Koi fish are colorful varieties of carp that are often kept in outdoor ponds and water gardens. They are known for their vibrant colors, which can include shades of orange, red, yellow, and white. Koi can grow quite large, sometimes reaching lengths of up to 3 feet, and they can live for many years, with some reaching over 200 years in ideal conditions. Originating from Japan, Koi fish are not only admired for their beauty but also hold cultural significance. They symbolize perseverance and strength, as they are known to swim upstream against strong currents. Koi are social creatures and thrive in groups, making them popular among aquarists and garden enthusiasts.