Osteoglossiformes
Osteoglossiformes is a relatively primitive order of ray-finned fish that contains two sub-orders, the Osteoglossoidei and the Notopteroidei. All of at least 245 living species inhabit freshwater. They are found in South America, Africa, Australia and southern Asia, having first evolved in Gondwana before that continent broke up.
The Gymnarchidae and the Mormyridae are weakly electric fish able to sense their prey using electric fields.
The mooneyes are often classified here, but may also be placed in a separate order, Hiodontiformes.
Members of the order are notable for having toothed or bony tongues, and for having the forward part of the gastrointestinal tract pass to the left of the oesophagus and stomach. In other respects, osteoglossiform fishes vary considerably in size and form; the smallest is Pollimyrus castelnaui, at just long, while the largest, the arapaima, reaches as much as.Phylogeny
Phylogeny based on the following works:
