The green neon tetra (Paracheirodon simulans) is a freshwater fish of the Characidae family of order Characiformes. It is native to the upper Orinoco and Negro Rivers in South America. This fish is similar in appearance to the closely related and better-known neon tetra, but it is slightly smaller, and its red patch is less pronounced, while the blue-green areas of the upper body are more brilliant. Also, its body is slimmer than that of the neon tetra. It grows to a maximum overall length of about 3.5 cm (1.4 in).