Spending most of its time close to the sea floor, the sicklefin weasel shark is a specialist predator of cephalopods. Its reproductive mode is viviparous, in which the unborn young form a placental connection to their mother. Females probably give birth twice a year, with each litter consisting of two to four pups. The sicklefin weasel shark is widely caught by artisanal fisheries and used for meat, fins, and fishmeal; its low natural abundance and reproductive rate mean that it cannot sustain much fishing pressure. Given that fishing activity is intense throughout its range, the International Union for Conservation of Nature (IUCN) has assessed this species as vulnerable.