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Discuss the Penguin Tetra in our Characins forum.

Penguin Tetra

Scientific Name: Thayeria obliqua
Family: Characidae, Hemigrammus Clade

About the Penguin 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: Middle (central) Amazon basin, middle Tocantins basin and Rio Guapore basin, South America. Streams in dense forested areas.

Compatibility/Temperament: A peaceful shoaling fish compatible with similarly peaceful fish like characins, rasbora, danio, gourami, angelfish, dwarf cichlids, small catfish and loaches.


Penguin tetras are one of the characins with a very unique feature compared to other tetras; they can swim at a 45 degree angle due to low buoyancy of their tails. In the wild, these fish lie just below the surface among dense vegetation and feed on insects falling on the surface. In both these traits they closely resemble the two pencilfish species Nannostomus eques and N. unifasciatus.

Should be kept in a group of six or more in a well-planted aquarium. Tank should be covered as they may jump if given the opportunity.

Up until about 1960 the related species Thayeria boehikei was shown in the literature under the common name of Penguin Tetra and that species is the more common in the hobby. It has a separate Profile.

The genus Thayeria was previously considered within the Sub-Family Tetragonopterinae, but this classification has for some time been deemed incertae sedis [Latin for "of uncertain placement"]. In a study published in 2010, it was determined that the Sub-Family Tetragonopterinae should only be used for species within the genus Tetragonopterus. [Robert Javonillo, Luiz R. Malabarba, Stanley H. Weitzman and John R. Burns, "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)]. Also, J. Marcos Mirande proposed several revisions to the Family Characidae based upon phylogenetic diagnosis in "Weighted parsimony phylogeny of the family Characidae (Teleostei: Characiformes)," Cladistics, Vol. 25, No. 6 (July 2009). Some genera have been moved to a new Sub-Family, while others are now (temporarily) assinged to a specific clade within the Family pending further study.

Penguin Tetra Diet

They are particularly carnivorous. They will appreciate live foods. Insects falling on the water surface are likely consumed by this fish. Feed frozen foods such as daphnia and bloodworms; should accept prepared foods.


Grows to 3.2 inches.

Minimum Tank Suggestion

30 inches in length.

Ideal water parameters for Penguin Tetra

Soft (hardness to 15 dGH) acidic (pH below 7.0) water, temperature 22-28C/72-82F.

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