It is the only member of the genus Acarichthys and is native to rivers in the Amazon and Essequibo basins in tropical South America, and has become established in southeastern Asia.

[2] The specific name honours the ichthyologist Johann Jakob Heckel, director of the Vienna Museum of Natural History, who studied and catalogued fish sent to him by collectors.

[3] Its common name is the "threadfin acara", referring to the elongated, free rays at the posterior end of the dorsal fin.

[5] This is a laterally-compressed, deep-bodied fish with a brownish-silver upper body, silvery flanks and a pale belly.

[6] A. heckelii is a benthic feeder, sifting through sand or mud on the river bed and feeding on the invertebrates present.