The term 'Large Marine Fish' can be summarized by two crossword solutions: TUNNY (5 letters) and OPAH (4 letters). TUNNY is a common name for several species of fish in the family Scombridae, which includes mackerels, tunas, and bonitos. OPAH is a large, colorful, deep-bodied fish found in tropical and temperate waters around the world. Both species are popular game fish and are highly sought after by anglers.