The dwarf tetra, as may be expected, is one of the smaller species of fish suitable for aquarium. Adult specimens rarely grow any larger than 0.75 inch.
Body colour is yellow-green to silver-grey, marked on the side with a dark line, which is underlined by a blue metallic line starting from the gill covers and terminating in a round dark spot at the base of the tail fin. The fins are hyaline and both the dorsal and anal fins are marked with a dark line at the base. The tail fin has a faint blue blush near the root, and is slightly smokey at the tips.