They knew he was big. For years, staff and visitors at Discovery Green have seen a large fish swimming in the park's 1-acre lake. Koi (Cyprinus carpio) and goldfish (Carassius auratus) are both in the ...

Once a simple food fish, koi have transformed into living jewels, with some fetching sky-high prices in the global luxury market. Here's how this happened. In the world of high-end pets, few creatures ...