Etymology: hemi-, half, allusion not evident, perhaps referring to smaller teeth and/or mouth compared to Brycon (although proposed as a subgenus of Tetragonopterus); brycon, generalized term used in generic names of many characiform fishes, derived from bryco, to bite, gnash teeth or eat greedily, originally an allusion to fully toothed maxillae. From: The ETYFish Project
Günther, A. 1864. Catalogue of the fishes in the British Museum. Catalogue of the Physostomi, containing the families Siluridae, Characinidae, Haplochitonidae, Sternoptychidae, Scopelidae, Stomiatidae in the collection of the British Museum 5: i–xxii + 1–455. BHLReference page.