Knifefishes and featherbacks belong to the Notopteridae family. They are easily recognized by their knife-like laterally compressed body, ribbon-like long anal fin, and small caudal fin confluent with the anal fin . Most members except Xenomystus genus have a distinct small quill-like dorsal fin. They are different from the electric knifefishes (Gymnotiforms) that have a similar swimming pattern.
Knifefishes are primarily freshwater fish with some species that can tolerate brackish water. In the wild, they are found in Africa and Southeast Asia. They are nocturnal fishes feeding on small surface-feeding fishes, crustaceans and insects.
There are 4 genera and 10 species worldwide. Malaysian is represented by 4 species.