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Phenacogaster tegatus

(Eigenmann, 1911)Formerly Vesicatrus tegatus Eigenmann, 1911

Last revised 2026Edit this page

On this page11 sections
Adult specimen.
Adult specimen.Graham Ramsay

Quick factsEdit

Max size
45mm SL1.8in SL
Aquarium size
60 × 30cm24 × 12in
Temp
20–28°C68–82°F
pH
6.0–7.5
Hardness
2–12dGH

Difficulty6 of 8 measures

Easy

How the rating is worked out

Space
medium tank
Water
flexible
Temp
flexible
Diet
unknown
Temperament
peaceful
Social
needs to be in a group
Compatibility
choose tankmates carefully

Other demands

Each of these can raise the rating on its own, whatever the measures above say.

Hardiness
unknown

Phenacogaster tegatus is a small characid from the upper rio Paraguay basin in Brazil and Paraguay and the Río Paraná in northeastern Argentina. It has been traded as 'six-eyed tetra', in reference to the two dark spots on each flank plus the eye. Peaceful but somewhat unsuitable for the general community aquarium, it is best kept in a group of at least 8-10 alongside similarly-sized characids and other small, non-predatory fishes.

Etymology

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Phenacogaster: from the Greek φέναξ (phenaks), meaning 'cheat, imposter', and γαστήρ (gaster), meaning 'belly, stomach'.

Distribution

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Recorded from the upper rio Paraguay basin in southwestern Brazil and Paraguay and the Río Paraná in Corrientes province, northeastern Argentina.

Type locality is given as 'Rio Jauru, upper Rio Paraguay basin, Brazil'.

Few details are available but images suggest this species to display a preference for relatively clear water with dense growth of submerged vegetation.

Aquarium size

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Standard length
45mm SL1.8in SL
Aquarium base
60 × 30cm24 × 12in
Volume
~54litres~14US gal

An aquarium with base dimensions of 60 ∗ 30 cm24 ∗ 12 in or more is recommended for a group.

Maintenance

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Relatively unfussy provided some cover is available but best-maintained in a natural-style set-up comprising a sandy substrate plus some driftwood roots, branches and aquatic plants.

The addition of dried leaf litter further emphasises the natural feel and as well as offering additional cover for the fish brings with it the growth of microbe colonies as decomposition occurs.

Water conditions

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Temperature
20–28°C68–82°F
pH
6.0–7.5
Hardness
2–12dGH

These recommendations come from this profile’s own figures. They contain affiliate links, so we may earn a commission.

Probably a micropredator feeding on tiny invertebrates and other zooplankton in nature.

In the aquarium it will accept dried foods of a suitable size but should also be offered daily meals of small live and frozen fare such as Artemia nauplii, Moina, grindal worm, etc.

Behaviour and compatibility

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Peaceful but somewhat unsuitable for the general community aquarium.

It’s perhaps best-maintained alongside similarly-sized characids, gasteropelecids, lebiasinids, smaller callichthyid or loricariid catfishes and diminutive, non-predatory cichlids.

Try to buy a mixed-sex group of at least 8-10 specimens, include other schooling fishes to provide security, and you’ll be rewarded with a more natural-looking spectacle.

Notes

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This species has been traded as 'six-eyed tetra' in reference to its colour pattern comprising two dark spots on each flank plus the eye.

Based on the extensive review of the genus by Lucena and Malabarba (2010)[1], in which nine new species were described, P. tegatus can be told apart from congeners by the following combination of characters: lateral line incomplete with 8-13 perforated scales; laterally elongate humeral spot present in both males and females and located on a vertical passing immediately anterior to the dorsal-fin origin, and thus distant from the pseudotympanum.

References

  1. Lucena, Z. M. S. de and L. R. Malabarba (2010). Descrição de nove espécies de Phenacogaster (Ostraiophysi: Characiiformes: Characidae) e comentários sobre as demais espécies do gênero. Zoologica 27(2), 263-604
  2. Eigenmann, C. H. (1911). New characins in the collection of the Carnegie Museum. Annals of the Carnegie Museum v. 8 (no. 1), 164-181
  3. Lucena, Z. M. S. de and C. de S. Gama (2007). Phenacogaster apletostigma, nova espécie de Peixe do Estado do Amapá, Brasil (Characiformes, Characidae). Revista Brasileira de Zoologia 24(1), 151-156
  4. Reis, R. E., S. O. Kullander and C. J. Ferraris, Jr. (eds) (2003). Check list of the freshwater fishes of South and Central America. CLOFFSCA. EDIPUCRS, Porto Alegre, i-xi + 1-729

Distribution

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