Koi are ornamental varieties of carp native to East Asia, bred for their spectacular colors and patterns. Their body is robust, with an ovoid shape and two sensitive barbels near the upper jaw, while the dorsal fin often has a serrated edge. The first color selections were made around the 19th century in Japan’s Niigata region, and since then over a hundred recognized varieties have been developed, from Kohaku (white with red) to Ogon (metallic) and Butterfly (elongated fins).
Habits
Kept in ponds with flowing water, koi are diurnal and social, swimming in groups; they feed both at the surface (with specially formulated floating food) and at the substrate, where they use their barbels to find invertebrates and organic debris.
Reproduction
Koi breeding occurs in spring and summer when water temperature rises to 18-24°C: males chase and push females before depositing thousands of sticky eggs on vegetation or substrate. Fertilization is external, and after hatching, the fry swim freely in 3-5 days, though mortality is high without specialized care.
Distribution
Although native to the Amur River basins and neighboring regions in East Asia, domestic koi are now globally distributed in ponds and water gardens across Europe, North America, Australia, and other temperate regions, where they adapt to various climate and water quality conditions.
