WordNet records no synonym and no antonym for driftfish. It is the only member of each of its synsets, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
larger butterfishes of the western Atlantic from the New York area to the northern Gulf of Mexico
small (6 inches) tropical butterfishes found worldwide
Synonyms, antonyms and the broader and narrower relations for driftfish come from Princeton University’s WordNet. Full sources and licences.