[6][7] Lampris guttatus is a large discoid and deeply keeled fish with an attractive form and a conspicuous coloration.

The body is a deep steely blue grading to rosy on the belly, with white spots in irregular rows covering the flanks.

The body is covered in minute cycloid scales and its silvery, iridescent guanine coating is easily abraded.

In May 2015, L. guttatus was shown to maintain its entire body core above ambient temperature, becoming the first known fish with this trait ('whole-body endothermy').

[11] This adaptation is important for maintaining brain and eye function during the wide range of temperatures it experiences with its vertical movements.

[8][9] Only L. guttatus is known to have retia within its gill arches (which are also insulated by fat), an arrangement that warms the entire body core including the heart.

[8][15] Lampris guttatus has a worldwide distribution, from the Grand Banks to Argentina in the Western Atlantic, from Norway and Greenland to Senegal and south to Angola in the Eastern Atlantic (also in the Mediterranean), from the Gulf of Alaska to southern California in the Eastern Pacific, in temperate waters of the Indian Ocean, and rare forays into the Southern Ocean.

[2] This species is presumed to live out its entire life in the open ocean, at mesopelagic depths of 50–500 m (160–1,640 ft), with possible forays into the bathypelagic zone.

[3] To better understand the depths L. guttatus inhabited in the tropical and temperate ocean waters, a study was performed, tagging them in the central North Pacific.

[further explanation needed] Based on those caught off the Hawaiian coast, squid and krill make up the bulk of their diet, though they also consume small fish.

Those caught along the Patagonian Shelf also showed a narrow range of prey, the most common of which was the deepwater onychotenhid squid (Moroteuthis ingens).