I personaly belive only two sharks can be kept in the home tank well,
My Choices For "Okay/Possibly" Captive Shark Species:
Bamboo Sharks, family Hemiscylliidae. Family Hemiscyllidae, the Bamboo, Epaulette Sharks, often misnomered as "catsharks". Excellent as juveniles and egg cases. Including the very commonly imported banded bamboo shark, Hemiscyllium indicum, and Chiloscyllium punctatum.
Madagascar, North Indian Ocean, Southwestern Pacific. Two genera, eleven species. The smaller members of this family constitute the most suitable aquarium species of sharks, given attention to filtration, arrangement of decor (space around the circumference), careful feeding...
And for a larger system the Epaulette Shark. Indo-West Pacific. To a little over three feet in length.
Not for the home tank
Nurse Shark. Most often collected out of the tropical West Atlantic as the most commonly (mis)offered shark species for aquarium use, though found in the Eastern Atlantic and Eastern Pacific coasts. To nearly fourteen feet in length (not a misprint). Unbelievable to me that folks would offer or buy this animal in place it in tiny systems
Blacktip Reef Shark. Indo-West to Central Pacific, including the Red Sea. To six feet in length. Litters of 2 to 5 pups. Offered in the aquarium trade regrettably all too often. Requires very large systems.
These sharks are all to often keept and die in the home tank.
Difficulties in captive care of sharks are several including the need for large, highly filtered systems, poor adaptability in terms of behavior for most open-water species, and oft-neglected chemical and physical environmental insults; in particular keeping cold to cool water species in warm to tropical temperatures, treating sharks with metal solutions and organophosphate containing remedies, and not maintaining a high, stable salinity. A consistent light regimen and the absence of metal in the system are absolute requirements for successful shark keeping.
Do not jump into this just because you work in a fish store dose not give you a PhD in marine bio.
Scott Michael sharks and rays. look for his book on sharks as an "o.k." guide