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").
Fourhorn poacher more commonly reach a TL of . The maximum recorded weight is , and the maximum recorded age is 7 years. The fourhorn poacher is preyed on by "Hippoglossus stenolepis". Its own diet consists of crustaceans including shrimp, crabs, isopods, amphipods, and ostracods, as well as bony fish, gastropods, and polychaetes. Fourhorn poacher The fourhorn poacher ("Hypsagonus quadricornis", also known as the four-horned sea-poacher) is a fish in the family Agonidae (poachers). It was described by Achille Valenciennes in 1829, originally under the genus "Aspidophorus". It is a marine, temperate water-dwelling fish which is known from the northern Pacific Ocean,