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
Dusky smooth-hound replaced tooth. Teeth are replaced at a rate of one row per 10 to 12 days. "M. canis" feeds mostly on crustaceans, polychaetes, and mollusks. Smooth dogfish also eat squid, worms, small fish, razor clams, and occasionally garbage. They are nocturnal scavengers and opportunistic predators. Their nocturnal activity helps them to take advantage of concentrations of crustacean prey. The mating season of smooth dogfish is from May to June. They are viviparous and have a yolk-sac placenta. Females can store sperm up to a year, but how long it can be used is not known. Their gestation period is 10