Macrourus berglax shrimps, amphipods, polychaete worms, bivalve molluscs, isopods, brittle stars, other echinoderms and comb jellies. The roughhead grenadier is a slow growing fish. The females mature at an age of about 14 years and a length of while males reach maturity at a length of . The potential fecundity of the female is 17,000 to 56,000 eggs. The eggs are laid in batches and spawning takes place at any time of year, with a peak in late winter and early spring. The roughhead grenadier is landed as a by-catch when fishing for Greenland halibut ("Reinhardtius hippoglossoides") and Atlantic halibut ("Hippoglossus hippoglossus").
Flying fish striking their prey. The oldest known fossil of a flying or gliding fish, "Potanichthys xingyiensis", dates back to the Middle Triassic, 235–242 million years ago. However, this fossil is not related to modern flying fish, which evolved independently about 66 million years ago. The term Exocoetidae is both the scientific name and the general name in Latin for a flying fish. The suffix "-idae", common for indicating a family, follows the root of the Latin word "", a transliteration of the Ancient Greek name . This means literally "sleeping outside", from "outside" and "bed", "resting place", verb root κει- "to