Paracheirodon simulansFalse neon tetra(Also: Green neon tetra; Neon)

Geographic Range

Paracheirodon simulans is native to the neotropical region. These fish, which are commonly called green neon tetras, are found in northwest Brazil to Colombia in the River Negro, and in Venezuela in the upper Orinoco River basin. ("Aquaria Central", 1997; Binohlan and Casal, 2003; "Paracheirodon simulans (Green Neon Tetra)", 1998; Robins, et al., 1991)


Paracheirodon simulans is mainly found in black water rivers of the South American tropics. They have been found in northwest Brazil in the River Negro to Colombia and Venezuela in the upper Orinoco River basin. Temperatures in these waters range from 72 to 82 degrees F. Because these jungle waters are typically shaded by overgrown trees, when keeping green neon tetras in captivity it is best to duplicate this natural shading by making the sides and bottoms of the aquarium dark. ("Aquaria Central", 1997; "Paracheirodon simulans (Green Neon Tetra)", 1998)

  • Aquatic Biomes
  • pelagic
  • rivers and streams

Physical Description

Green neon tetras appear similar to neon tetras, Paracheirodon innesi, although they are smaller and the red patch on the lateral body is less pronounced. The lateral blue-green stripe extends to the base of the caudal fin. These fish can grow to a maximum overall length of approximately 2.5 cm. ("Aquaria Central", 1997; "Wikiverse", 2004)

  • Range length
    2.5 (high) cm
    0.98 (high) in


The pattern of development in these animals has not been characterized. However, eggs of P. axelrodi generally develop within 24 to 30 hours of fertilization. (Gilbert, 2003)


Paracheirodon species generally spawn in schools, although single males and females may become closely associated while the female releases her eggs and the male releases his sperm.

Information on reproduction in tetras comes from specimens housed in aquaria. Female neon tetras lay approximately 130 eggs on the substrate. Fry hatch in about 24 hours. These fish tend to breed every few weeks. The larvae of these fish are sensitive to ultraviolet radiation, so are restricted in the areas in which they may lay their eggs. Generally, eggs are left under canopies to ensure they hatch. Eggs are typically laid during the rainy and wet seasons when water levels are higher. ("Aquaria Central", 1997; Binohlan and Casal, 2003)

  • Breeding interval
    Green neon tetras breed every few weeks.
  • Breeding season
    Breeding season in the wild is influenced by water levels, generally occurring during rainy seasons. In captivity these fish can reproduce at any time of year.
  • Average number of offspring
    130 eggs
  • Average time to hatching
    24 hours

Once eggs are laid, adult tetras do not provide any further parental care. Adult tetras may even eat their eggs and larvae. ("Aquaria Central", 1997; Binohlan and Casal, 2003)

  • Parental Investment
  • no parental involvement
  • pre-fertilization
    • provisioning
    • protecting
      • female


The longevity of green neon tetras has not been reported.


There is little information on the behavior of P. simulans. They are typically found in schools of 6 fish or more. These are also thought to be the schools within which they mate. Small localized migrations may take place in response to changing water levels. ("Aquaria Central", 1997; "Paracheirodon simulans (Green Neon Tetra)", 1998)

Home Range

Home ranges of these animals in the wild hav not been reported.

Communication and Perception

Green neon tetras transmit sound energy to the auditory organ by the use of a Weberian apparatus. This structure allows these fish to have better hearing characterized by large bandwidths and high sensitivity. (Hertwig and Schneider, 1999)

In addition to their hearing, green neon tetras have eyes, and can perceive visual signals, although the role of such signals in their commmunication has not been documented. Tactile communication may have some role in mating.

Food Habits

Paracheirodon simulans is omnivorous. These fish tend to eat small live foods such as crustaceans, fish larvae, and insects. ("Paracheirodon simulans (Green Neon Tetra)", 1998)


Patterns of predation on these animals in their natural habitat have not been reported. However, it is likely that they are eaten by larger fish and other larger, aquatic predators at all life stages. The structural color that makes up their neon stripes may help to confuse predators and make it more difficult to catch these small fish. They are also protected from predators to some extent through their schooling behavior.

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

The role of P. simulans in its ecosystem has not been investigated. Green neon tetras act as important predators on their small, invertebrate prey, and serve as important food sources for larger, aquatic predators.

Economic Importance for Humans: Positive

Green neon tetras, and neon tetras in general, are important in the pet trade. They are popular for their bright coloration. ("Aquaria Central", 1997)

Economic Importance for Humans: Negative

Paracheirodon simulans has no reported adverse effect on human economies.

Conservation Status

Paracheirodon simulans is not listed by CITES or IUCN as a conservation concern. This species is common within their native range and widely used in the pet trade.


Tanya Dewey (editor), Animal Diversity Web.

Nitasha Bali (author), University of Michigan-Ann Arbor, William Fink (editor, instructor), University of Michigan-Ann Arbor.



living in the southern part of the New World. In other words, Central and South America.

World Map


uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


an animal that mainly eats meat


uses smells or other chemicals to communicate


having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.


animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

external fertilization

fertilization takes place outside the female's body


union of egg and spermatozoan


mainly lives in water that is not salty.


having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.


An animal that eats mainly insects or spiders.


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).


having the capacity to move from one place to another.


specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.


reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.


An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).

pet trade

the business of buying and selling animals for people to keep in their homes as pets.


the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.


rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

seasonal breeding

breeding is confined to a particular season


reproduction that includes combining the genetic contribution of two individuals, a male and a female


associates with others of its species; forms social groups.


uses touch to communicate


the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.


movements of a hard surface that are produced by animals as signals to others


uses sight to communicate


animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)


Aquaria Central. 1997. "Aquaria Central" (On-line). Neon tetra (Paraceirodon innesi). Accessed October 27, 2004 at 1998. "Paracheirodon simulans (Green Neon Tetra)" (On-line). Fish Index. Accessed October 27, 2004 at

Wikipedia. 2004. "Wikiverse" (On-line). Green Neon Tetra. Accessed October 28, 2004 at

Binohlan, C., C. Casal. 2003. "Paracheirodon simulans" (On-line). Fishbase. Accessed October 27, 2004 at

Fink, W., S. Weitzman. 1983. Relationships of the Neon Tetras, A Group of South American Freshwater Fishes, with Comments on the Phylogeny of New World Characiforms. Bulletin of the Museum of Comparative Zoology, 150/6: 339-358.

Fink, W., S. Weitzman. 1974. The So-Called Cheirodontin Fishes of Central America with Descriptions of Two New Species(Pisces: Characidae). Smithsonian Contributions to Zoology, 172: 1-35.

Gilbert, S. 2003. Developmental Biology. 7th ed. Sunderland, MA: Sinauer Associates Inc..

Hertwig, I., H. Schneider. 1999. Comparative light and electron microscopic study of the auditory organs of two species of fishes (pisces): Hyphessobrycon simulans (Ostariophysi) and Poecilia reticulata (Acanthopterygii). European Journal of Comaparative Morphology, 37/1: 17-28. Accessed October 27, 2004 at

Robins, C., R. Bailey, C. Bond, J. Brooker, E. Lachner, R. Lea, W. Scott. 1991. World Fishes Important to North Americans. Bethesda, Maryland, USA: American Fisheries Society.