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Red Eye Tetra

Scientific Name: Moenkhausia sanctaefilomenae
Family: Characidae, Hemigrammus Clade

About the Red Eye 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: Paraiba, Sao Francisco, upper Parana, Paraguay and Uruguay river basins in Argentina, Brazil and Paraguay. Inhabits clearwater rivers thick with floating plants and aquatic Echinodorus species.

Compatibility/Temperament: Peaceful but quite active fish that may frighten sedate fish such as dwarf cichlids and angels. Good for community tanks with similar active tetras, catfish and loaches, danios, livebearers.


A very active but peaceful tetra that prefers a densely planted aquarium with adequate swimming space lengthwise, a dark substrate and subdued lighting that can be achieved with floating plants that are part of its native habitat. It has a wider tolerance than most characins for water parameters due to the fluctuation of its native waters between the dry and rainy seasons. Should be kept in a group of at least 7 but preferably a few more; this, plus a spacious tank, will reduce the possibility of fin-nipping.

Females are rounder in the body that males, particularly at breeding times; spawns in the normal characin method, and will eat the eggs if not removed after spawning.

This species was originally described as Tetragonopterus sanctae Filomenae [subsequently corrected to T. sanctaefilomenae] by Steindachner in 1907 and also in 1908 by Eigenmann as Moenkhausia australe. Gomez and Chebez in 1996 reassigned the species as Moenkhausia sanctaefilomenae [as the prior species name] and Benine in Reis et al. (2003) assigned M. australe as a junior synonym of M. sanctaefilomenae. Eigenmann had erected the genus Moenkhausia in 1903, named to honour his friend W.J. Moenkhaus.

The genus Moenkhausia was previously considered within the Sub-Family Tetragonopterinae, but this classification, as indeed that of the entire Characidae family, has for some time been deemed incertae sedis [Latin for "of uncertain placement"]. Javonillo, et al. (2010) proposed that the Subfamily Tetragonopterinae should only be used for species within the genus Tetragonopterus. J. Marcos Mirande (2009) 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) assinged to a specific clade within the Family pending further phylogenetic study.


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).

Red Eye Tetra Diet

Accepts prepared foods including flake and frozen.


Up to 2.8 inches.

Minimum Tank Suggestion

36 inches in length

Ideal water parameters for Red Eye Tetra

Soft to moderately hard (hardness to 20 dGH), acidic to slightly basic (pH to 8.0) water, temperature 22-26C/72-79F.

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