Koi Fish

Koi fish are often found in decorative ponds. Here is a short explanation of them from Wikipedia: Koi:

Koi (鯉, English: /ˈkɔɪ/, Japanese: [koꜜi]) or more specifically nishikigoi (錦鯉, [ɲiɕi̥kiꜜɡoi], literally "brocaded carp"), are colored varieties of Amur carp (Cyprinus rubrofuscus) that are kept for decorative purposes in outdoor koi ponds or water gardens.
Koi is an informal group of the colored variants of C. carpio. Several varieties are recognized by the Japanese. Koi varieties are distinguished by coloration, patterning, and scalation. Some of the major colors are white, black, red, orange, yellow, blue, and cream. The most popular category of koi is the Gosanke, which is made up of the Kohaku, Taisho Sanshoku, and Showa Sanshoku varieties.

I have very little experience with fish or fishing but I do know that carp are only edible when they come from a pond, lake, stream, or river that is not polluted. When I was young, I heard about how to cook a carp. You cook it on a board until the meat is tender and well cooked and then you eat the board.