Green Neon Tetra

The green neon tetra grows to a standard length (SL) between 10–20 mm (0.39–0.79 in). There is considerable overlap in both length and body depth between this species and others in the genus. This fish may be distinguished from the two other Paracheirodon species by a few key characteristics. For example, unlike the neon tetra and cardinal tetra, the blue-green lateral stripe in this species extends all the way to the base of the tail. The red underside is less pronounced. Additionally, this is the only species in the genus to possess premaxillary teeth in 2 separate rows. P. simulans typically possesses 8 dorsal fin rays, 8 pectoral fin rays, and 6 pelvic fin rays, all of which are branched.

This fish loses its brilliant blue and red colours when lights are switched off, but regains them when lights are switched on again.

Though the green neon tetra is described as being from the Negro and Orinoco Rivers, it may be restricted to the uppermost portion of the tributaries of these rivers, as well as within the terra firma and heavily planted wetland areas between. Though there is some overlap with the range of P. axelrodi, the two species are thought to partition their habitat. In wetland areas of their range, dissolved oxygen concentrations range from 0.7 to 4.4 mg/L and pH from 4.3 to 4.7, with averages of 2.1 mg/L and 5.0, respectively. Temperatures may range between 25–35 °C (77–95 °F), with no stress observed at the extremes.