i like to go catch opah
Opahs are also called moonfish or sunfish. 
what is the difference 
They are all the same. They are also called kingfish, redfin ocean pan, and Jerusalem haddock. They are large and colorful fishes.
All i know is they are tasty!
Opahs are frequently caught as bycatch in many longline tuna fisheries. Opah is becoming increasingly popular in seafood markets. It first became popular as a sushi and sashimi in the late 1980s and early 1990s. The meat is lightly flavored and lends itself well to a variety of preparations, principally sauté. Opah flesh has a light-pink to orange color, but turns white when cooked. It is popular in Hawaii, especially in restaurants. An average of 35% of an opah's weight is consumable, with the remaining 65
Opah
Opahs (also commonly known as moonfish, sunfish (not to be confused with Molidae), kingfish, redfin ocean pan, and Jerusalem haddock) are large, colorful, deep-bodied pelagic lampriform fishes comprising the small family Lampridae (also spelled Lamprididae). Only two living species occur in a single genus: "Lampris" (from the Greek "lamprid-", "brilliant" or "clear"). One species is found in tropical to temperate waters of most oceans, while the other is limited