Lycodes gracilis was first formally described in 1867 by the Norwegian theologian and naturalist Michael Sars with the type locality given as Drøbaksundet in Oslofjord in Norway.

[1] The specific name gracilis means "slender" and is a reference to the less robust body of this fish compared to its known relatives in 1867.

[4] Lycodes gracilis has a light grey to dark brown overall colour, marked with up to 31 small black spots along the flanks, these may be absent or not very conspicuous.

This ia a long tailed eelpout, with the distance from the snout to the anal fin being between 35% and 47% of the total length.

[5] Lycodes gracilis is found in the eastern North Atlantic Ocean and adjoining Arctic Ocean from eastern Greenland and Iceland north to Svalbard, east to the southern Barents Sea and south to the Shetland Islands and the Kattegat and Skagerrak.