Speckled smooth-hound seabed on the continental shelf at depths of between . Reports of this fish occurring in the Atlantic Ocean off the coast of Argentina are thought to be erroneous, and are likely to refer to the narrownose smooth-hound ("Mustelus schmitti"), another shark that is speckled with white spots. The speckled smooth-hound is ovoviviparous with eggs that develop within the female and hatch into juvenile fish which are about at birth. Litter sizes are typically seven. Along with the humpback smooth-hound ("Mustelus whitneyi") and the spotted houndshark ("Triakis maculata"), this fish is known to local fisheries as "tollo" and is caught
Slender smooth-hound about one-sixth of the total length; the lower caudal fin lobe is indistinct, while the upper lobe has a strong ventral notch near the tip. The skin is densely covered by small, overlapping dermal denticles. The crown of each denticle is mounted on a short stalk and bears three horizontal ridges leading to marginal blade-like teeth, with the central tooth particularly long. This species is plain brownish-gray above and lighter below. It grows up to long and in weight, with females reaching a slightly larger size than males. The slender smooth-hound is likely a schooling species. It preys on a