鯉魚 (Koi) are colorful fish that are often kept in outdoor ponds and water gardens. They are a domesticated variety of the common carp and are known for their vibrant colors and patterns, which can include shades of red, orange, yellow, and black. Koi are popular in Japanese culture and are often associated with good fortune and perseverance. These fish can grow quite large, sometimes reaching lengths of over three feet. Koi are social creatures and thrive in groups, making them a favorite among fish enthusiasts. Proper care, including clean water and a balanced diet, is essential for their health and longevity.