The genus Harpagifer was described in 1844 by the Scottish naval surgeon, naturalist and Arctic explorer John Richardson, with Batrachus bispinis, a species which had been described in 1801 by Johann Reinhold Forster, as its type species by monotypy.

[4] There are currently 12 recognized species in this genus:[5] Harpagifer spiny plunderfishes have a relatively short and compressed body, lacking scales and with a large broad head.

[5] Harpagifer spiny plunderfishes are largely restricted to Subantarctic islands, although there is one species which occurs along the coasts of the Antarctic Peninsula and another which is found around the southern tip of South America.

They are slow growing fish, reaching sexual maturity between the ages of 3 and 5 years old and around a total length of 7.5 cm (3.0 in) and they have been observed building nests and guarding their broods.

They are important to the ecology of the areas where they are found as they are common prey for larger fishes and sea birds.