The genus Thoracocharax is monophyletic and is sister to Carnegiella and Gasteropelecus.

[4] The four lineages are found in the following rivers: The genus name, Thoracocharax, is derived from the Greek θώραξ (thṓraks), meaning breastplate or cuirass coupled with the word Charax, type genus of the Order Characiformes, which comes from the Ancient Greek χάραξ (chárax), meaning a palisade of pointed sticks, in reference to the densely packed sharp teeth of the fish.

The species epithet, stellatus, is Latin for starry or studded with stars, a reference to the fish's platinum-coloured shiny appearance.

[1] In the wild, feeding occurs at sunrise and sunset, and analysis of the stomach contents of 88 specimens indicates that this species is mostly insectivorous (99.6% of stomach contents were insects) and consisted mostly of ants, beetles, and mayflies.

[1] An Amazon biotope-style tank is preferred (e.g. driftwood branches, sand substrate, leaf litter).