Because of their gracefulness, the longevity of their lives, and their gorgeous colors, it is easy to see why koi fish are so popular to outside ponds. Koi fish also have many traits that make them an ideal fish to thrive in an outside pond.
Since it is realistic to think that koi fish will grow to be large fish they require a pond that is about five hundred gallons or more. Typically the health of the koi depends a lot upon the amount of space that they are provided with and the quality of the water. Koi fish are cold water fish and do very well in water temperatures that are between 60 and 67 degrees Fahrenheit.