Characidae, Hemigrammus Clade Common Name:
Glowlight Tetra Origin and Habitat:
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. Glowlight Tetra Diet
Will accept any of the usual prepared foods including flake and frozen. Size
Grows to 1.6 inches. Minimum Tank Suggestion
24 inches in length 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. Description
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; in the second photo below, the male is the upper fish and the female the lower. 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 et.al. (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). References:
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). Contributing Members
The following members have contributed to this profile: Byron