Naupygus bucklandi was a holocentrid-grade beryciform represented by skulls and, unusually for the London Clay, some articulated postcranial material. Its cranium is low and broad with strong ridges, and the family relationship suggests a visually oriented marine predator. Living squirrelfishes and soldierfishes feed largely on crustaceans and smaller fishes, making a similar carnivorous role plausible, although direct diet evidence is absent.

Because more than the head is known in some specimens, Naupygus helps bridge the gap between the exceptional London Clay cranial record and the otherwise poorly known body shapes of its teleost fauna. The deeply sculptured ethmoid and skull-roof regions give the head a strongly reinforced appearance.