Synodontids are a popular group of catfish for the aquarium, partly because they do not grow to a large size, but also because they are active and attractively patterned in many cases.
Defining a fish is harder than it seems. To most people, it is an animal that lives and breathes in water. Some fish, however, emerge onto land, breathe air, and use their fins like legs. And many other animals, including amphibians, mammals, and invertebrates, live in water. To add further confusion, some creatures called fish—starfish, jellyfish, and cuttlefish—are not really fish at all.
Kryptopterus bicirrhus (Asian Glass Catfish), is unusual in a number of ways. As its name implies, it is transparent and some internal organs and the skeleton can be seen. It is also one of the few catfishes that is not benthic (bottom-dwelling), remaining in mid-water. The body is compressed, similar to most other pelagic fishes, rather than depressed. They are shoaling catfishes that must be kept in small groups, not individually, otherwise they will not feed.
All catfishes have barbels: Whisker-like filaments surrounding the mouth. It is this feature, resembling feline whiskers, that has given the Siluriformes the common name of catfishes. There are great variations in the form and number of barbels, dependent on species. Most species have two to four pairs of barbels, usually filamentous, but sometimes fringed with smaller branches as in the African Synodontis nigriventris (upside-down catfish), or built into large sucker-like lips.
