Koi are pretty big fish that require a lot of space (the "big fish, small pond" thing doesn't work for them). With the right care, koi can grow to be between 2 and 3 feet (0.6 and 0.9 meters ...

Among the most difficult to save are those that live in water. David and Jane Pierce have owned — and loved — these koi fish for 25 years.Credit...Stella Kalinina for The New York Times ...

These polychromatic swimmers are definitely deserving of admiration. Koi fish have got a lot going for them. "[They are] not only a pet, but also art," says Taro Kodama, president of Kodama Koi Farm. ...