<http://www.differencebetween.net/science/difference-between-koi-and-goldfish/#article>
<http://schema.org/description>
"Difference Between Koi and Goldfish Koi vs Goldfish Koi and goldfish have more similarities than differences. For starters, they are both members of the cyprinidae, or carp family of fish. In fact, they are so closely related that they are able to breed with each other, though their offspring will be sterile. Immature koi and goldfish can often be mistaken"
<http://www.differencebetween.net/science/difference-between-koi-and-goldfish/>