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Glowlight Tetra

Scientific Name: Hemigrammus erythrozonus
Family: Characidae, Hemigrammus Clade

About the Glowlight Tetra

Species Type: Freshwater Fish
Category: Characins

Care Level: Very Easy. Will tolerate a wide range of water parameters including pH, temperature and hardness. Can tolerate higher nitrate levels than other fish and is hardy enough to withstand the cycling process. Will readily eat prepared foods and has no special care requirements.

Origin: Essequibo River basin, Guyana, South America.

Compatibility/Temperament: Very peaceful, a good addition to a community tank of soft, acidic water fish like peaceful characins, dwarf cichlids, small catfish and loaches, rasbora, gourami. Must be in a group of at least six but preferably more.


In a well-planted aquarium with subdued lighting and its preferred water parameters (soft and acidic), this fish really lives up to its name of glowing. Its colour tends to pale in basic or harder water.

A shoaling fish by nature, it must be kept in groups of at least six but preferably more. It likes to "hide" among plant thickets, coming out to swim in the open; it remains in the lower half of the aquarium, often close to the substrate. It will readily surface to feed.

Easy to spawn; females are stockier than males. All available fish are commercially bred; it is very rare to find wild-caught fish of this beautiful species. The lifespan is about four years.

This species was originally described by M.L. Durbin in 1909.

The genus Hemigrammus--the name from the Greek meaning "with half line," a reference to the incomplete lateral line--was erected as a subgenus of Poecilurichthys by T.N. Gill in 1858 but has been recognized as a distinct genus since Gery (1977). There are presently about 50 valid species. The classification is deemed incertae sedis [Latin, "of uncertain placement"]. It was formerly considered within the Subfamily Tetragonopterinae, but Javonillo (2010) suggest that this subfamily should be restricted to species within the genus Tetragonopterus since they do not share physiological characteristics with species in other genera such as Hemigrammus.

None of the diagnostic characteristics presently used to describe species in Hemigrammus, including the incomplete lateral line which gave rise to the genus name, are unique to the genus. Mirande (2009) states that the genus is not monophyletic, a view shared by most ichthyologists working with the characidae. [A monophyletic genus is one wherein the species share a common ancestor, thus linking them together physiologically.] Mirande has proposed several revisions to the Family Characidae based upon phylogenetic diagnosis. Some genera have been moved to a new Subfamily, while others are now (temporarily) assigned to a specific clade within the Family pending further study.

Hemigrammus has until recently been differentiated from Hyphessobrycon solely on the basis of the fish in Hemigrammus possessing a scaled caudal fin; this however is now known to be unreliable, since it occurs in intermediate conditions (de Lucina, 2003).


de Lucena, Carlos Alberto Santos (2003), "A new characid fish, Hyphessobrycon scutulatus, from the Rio Teles Pires drainage, upper Rio Tapajos system (Ostariophysi: Characiformes: Characidae)," Neotropical Ichthyology 1 (2), pp. 93-96.

Gery, Jacques (1977), "Characoids of the World," TFH Books.

Javonillo, Robert, Luiz R. Malabarba, Stanley H. Weitzman and John R. Burns (2010), "Relationships among major lineages of characid fishes (Teleostei: Ostariophysi: Characiformes), based on molecular sequence data," Molecular Phylogenetics and Evolution, Vol. 54, No. 2 (February 2010).

Mirande, J. Marcos (2009), "Weighted parsimony phylogeny of the family Characidae (Teleostei: Characiformes)," Cladistics, Vol. 25, No. 6 (July 2009).

Glowlight Tetra Diet

Will accept any of the usual prepared foods including flake and frozen.


Grows to 1.6 inches.

Minimum Tank Suggestion

24 inches in length

Ideal water parameters for Glowlight Tetra

Soft to moderately hard (hardness to 15 dGH) and acidic to slightly basic (pH to 7.5) water, temperature 24-28C/74-82F. Occurs in tributaries of the Essequibo River in forested areas where the water is highly acidic and brown from tannins.

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