Koi fish are colorful ornamental varieties of common carp. They are popular in ponds and gardens, known for their vibrant colors and distinctive patterns. Originating from Japan, koi have been selectively bred for centuries. These fish can symbolize good luck, prosperity, and perseverance in Japanese culture. Koi come in various colors such as red, orange, yellow, blue, and black, and their patterns include Kohaku, Taisho Sanke, and Showa Sanshoku, among others. They require proper care, including a suitable pond environment and balanced nutrition.