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 may also receive secondary nutrition in the form of histotroph ("uterine milk") produced by the mother. When the embryo is long, it emerges from the capsule, which by that time has become translucent and gelatinous. Embryos long have well-developed external gill filaments. The external yolk sac is entirely absorbed when the embryo is long and close to being born. Males and females reach sexual maturity at approximately long. Harmless to humans and of no economic value, the slender smooth-hound is occasionally caught incidentally in bottom trawls and on bottom longlines. Much of its northern range lies in little-fished waters, and