cero vs king mackerel

cero and king mackerel both are nouns.

Word	Noun	Adjective	Verb	Adverb
cero	Yes	No	No	No
king mackerel	Yes	No	No	No

As nouns, cero and king mackerel are synonyms defined as:

cero and king mackerel: large mackerel with long pointed snout; important food and game fish of the eastern Atlantic coast southward to Brazil

Other synonyms of cero include cavalla, Scomberomorus cavalla.

cero (noun)	king mackerel (noun)
large edible mackerel of temperate United States coastal Atlantic waters	large mackerel with long pointed snout; important food and game fish of the eastern Atlantic coast southward to Brazil
large mackerel with long pointed snout; important food and game fish of the eastern Atlantic coast southward to Brazil