Fish sold as “freshwater sharks” in aquarium shops are seldom true sharks. Many different species of silvery fish are marketed as fresh water sharks, even though they really belong to other fish groups and are not even closely related to sharks. One example of such a fish is the popular Bala shark (Balantiocheilus melanopterus). This fish is also known as the Tricolor sharkminnow. If you get a “so-called” shark, it is important to find out its true name since this will make it possible for you to provide it with a suitable environment and diet. Many so-called sharks are for instance not even predatory and must be kept on a diet that is very dissimilar from the diet of most true sharks.
Getting a “so called shark” for your aquarium is usually a much better idea than trying to purchase a real shark. A lot of the true shark species are endangered species in should not be removed from the wild. They will also grow very large and will not do well in small, confined spaces such as aquariums. Sometimes sharks are caught and placed in aquariums for conservational reasons, but these aquariums are much larger than those found in the home of the typical hobby aquarist. They are also cared for by educated shark experts that know how to handle these sometimes aggressive animals.
Most true sharks are marine animals, but you can find freshwater sharks too, e.g. in Australia and Nicaragua. The marine Bull shark (Carcharhinus leucas) is famous for its ability to adjust to freshwater environments. None of these true freshwater sharks can be recommended as pets. The Bull shark will for instance grow up to 11.5 feet (3.5 meters) in length. Thriving bull sharks are found in well kept public aquariums, but these aquariums are of course very large. Legally keeping a Bull shark in captivity involves a lot of paper work, since these creatures are considered near threatened by CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) and included in the IUCN Red List of Threatened Species.
If you have a large saltwater aquarium, you can keep some of the smallest marine true shark species. If you have no previous experience from marine aquariums, you should however ideally start with much sturdier marine species and gradually increase your skills before you try keeping a true saltwater shark. Maintaining a marine aquarium is difficult and will typically call for expensive investments, but it is also very rewarding since you get to keep a lot of fascinating fish species that can not be housed in freshwater aquariums.
The Bala shark mentioned earlier in this article is a freshwater species that originates from Asia. Before you get one, you should keep in mind that it can reach a length of 14 inches (36 centimeters). You should ideally get at least six Bala sharks, since this is a schooling fish that can feel stressed when kept alone without any other members of its own species.
Another so-called shark that often astonishes its keeper by growing really, really big is the Black shark (Labeo chrysophekadion). This fish is often offered by fish stores when it is no bigger than 2 inches (5 centimeters), but can eventually reach a size of 32 inches (82 centimeters). This species is also known as “Giant Black Sharkminnow”.