Notopteroidei
Notopteroidei is a suborder of the order Osteoglossiformes that contains the extant families Gymnarchidae (aba), Notopteridae (feather backs and knifefish) and Mormyridae (elephantfishes), as well as several extinct taxa. The Mormyridae are weakly electric fishes, able to locate prey in turbid water. References

Osteoglossiformes
Ray-finned fish suborders