The striking Red-Tailed Sharks are originally from Thailand, where their natural habitat includes clear, fast moving waters. For several years, they were believed to be extinct in the wild. While that is no longer the case, they are critically endangered. However, the species flourishes in the aquarium trade as their distinct deep black body and bright orange tail make them quite popular. They reach a length of about 6 inches, and while mostly slender, they tend to be widest and tallest around the middle. They can often be confused with their close relative, the rainbow shark. However, the rainbow shark's body will be grey, and it will usually have more colored fins than the red-tail (in the photo below, the fish in the front is a rainbow shark, while the other two are red tails).
Although red tail sharks are popular, there are two things to consider before buying one impulsively. Firstly, most red tail sharks sold in the aquarium trade will not yet be full grown, so even if they will fit in a smaller tank when first purchased, they will eventually require at least a 40 gallon tank to have room to both hide and move about comfortably. Secondly, they are considered semi-aggressive fish. This does not mean that all of them are very aggressive, but most will at least be territorial, and some may actively pursue other tank mates. For this reason, they are not generally recommended for peaceful community tanks, as smaller fish may be picked on. This is also why larger tanks are better for red tail sharks, as it allows plenty of room for both them and other fish. An example of a good tankmate would be larger species of rainbowfish, as they are both large enough and fast enough that the red tail poses little threat to them. It is almost never a good idea to try keeping multiple red tail sharks in a single tank; they are loners, not social fish.
Red tail sharks should ideally be kept in aquariums that imitate their natural environment, with tropical temperatures in the mid to upper 70s, neutral pH (preferably between 6.5 and 7.5), good water flow, and plenty of places to hide. While artificial decorations may be used, they will be most enjoyable with real ones, and may often be observed "cleaning" plants, driftwood, or rocks, which usually means they are eating algae or small organisms off of them. However, they should not be considered efficient algae eaters or "tank cleaners", such as plecos or snails. They are omnivores, and should be provided with a varied diet in addition to what they scavenge about the tank. They can be fed primarily with a sinking wafer for bottom feeders, such as AquaLife CS Pro Sticks, and supplemented with frozen/dried foods like worms or shrimp.