Fancy fish are a type of ornamental fish that are kept in aquariums or ponds for their attractive colors and patterns. Two examples of fancy fish are KOI and OPAH. KOI is a species of carp that is native to East Asia and is known for its bright colors and patterns. OPAH is a species of large, deep-bodied fish found in tropical and temperate waters around the world. It is characterized by its bright red color and large size.