The pelagic fangtooths are among the deepest-living fish found as far as 5,000 meters (16,400 feet) down. They are more commonly found between 200 - 2,000 meters (660 - 6,560 feet) however, and juveniles apparently stay within the upper reaches of this range. They may undergo diel migrations as is common with many deep-sea fish: by day these fish remain in the gloomy depths and towards evening they rise to the upper layers of the water column to feed by starlight, returning to deep water by daybreak. Fangtooths may form small schools or go alone. They are thought to use contact chemoreception to find prey, relying on luck to bump into something edible.
The smaller teeth and longer gill rakers of juveniles suggest they feed primarily by filtering zooplankton from the water, while the deeper-living adults target other fish and squid. The fangtooths' oversized teeth and mouths are a common feature among the miniature beasts of the deep (cf. viperfishes, daggertooths, bristlemouths, barracudinas, anglerfishes), thought to be an advantage in these lean waters where anything encountered (even if it is larger than the fish) must be considered a possible meal. The fangtooths in turn are preyed upon by other large pelagic fish, such as tuna and marlin.