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").
Demersal fish and invertebrates that pass overhead. Some species have a worm-shaped lure growing out of the floor of the mouth, which they wiggle to attract prey. Stargazers are venomous and can deliver electric shocks. They have been called "the meanest things in creation." Other examples of coastal demersal fish are cod, plaice, monkfish and sole. Deep water demersal fish occupy the benthic regions beyond the continental margins. On the continental slope, demersal fishes are common. They are more diverse than coastal demersal fish, since there is more habitat diversity. Further out are the abyssal plains. These flat, featureless regions occupy about