Lycodes vahlii was first formally described in 1831 by the Norwegian zoologist Johannes Christopher Hagemann Reinhardt with its type locality given as Julianehåb in Greenland.

[3] The specific name honours the Danish botanist and pharmacist Jens Laurentius Moestue Vahl,[4] who gave his collection of plant and fish specimens to the University of Copenhagen, where Reinhardt held the post of Professor of Zoology.

It has an elongate body which has a depth at the origin of the anal fin 7% to 11% of the total length and it has a long tail with the distance from the snout to the origin of the anal fin being36& to 44% of the total length.

There are small pores on the head and there is a dense covering of scales on the body, including the abdomen, but on the forward parts of the bases of the dorsal, anal and pectoral fins are naked.

It is an epibenthic to mesobenthic species which lives on soft substrates at depths between 39 and 1,200 m (128 and 3,937 ft) where the water temperature is 1.4 to 5.8 °C (34.5 to 42.4 °F).