Why is my Penguin Tetra swimming facing upwards?

This is entirely normal behaviour. Penguin Tetras naturally rest and swim at a 30-degree angle with their heads pointing upwards. It is believed to be an evolutionary trait that helps them blend in with vertical aquatic plants in the wild.

Are Penguin Tetras fin nippers?

They are generally peaceful, but they can become fin nippers if they are stressed or kept in a group that is too small. Keeping them in a proper shoal of at least 6 to 10 individuals usually curbs any nipping behaviour.

How many Penguin Tetras should I keep together?

You should keep an absolute minimum of 6 Penguin Tetras together, but a group of 10 or more is highly recommended. Larger shoals help them feel secure, reduce stress, and display their best natural behaviours.

Where do Penguin Tetras prefer to swim in the tank?

They are highly active fish that primarily occupy the middle and upper levels of the aquarium. They appreciate open swimming space in the centre of the tank.

Will Penguin Tetras eat my dwarf shrimp?

Adult dwarf shrimp like Neocaridina are generally safe, but Penguin Tetras are micro-predators and will happily eat baby shrimplets that fit into their mouths. A densely planted tank will provide some hiding spaces for the young.

FreshwaterTropicalBeginner

Penguin Tetra

Thayeria boehlkei

A striking, active shoaling fish instantly recognisable by its bold black stripe and highly unusual tail-down swimming posture.

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Ideal Conditions

Temperature: 22 – 28 °C
pH range: 5.5 – 7.5
Hardness: 2 – 15 dGH
Adult size: 5 – 6 cm
80 Litres: 80 litres+
Lifespan: 3 – 5 years
Diet: Omnivore
Water flow: Moderate
Preferred setup: Well-planted perimeters with open central swimming space. Dark substrate and floating plants recommended.

About the Penguin Tetra

The Penguin Tetra (Thayeria boehlkei) is a highly popular freshwater fish native to the lush tributaries of the Amazon and Araguaia rivers. It is frequently referred to as the Hockey-stick Tetra due to the distinct black band that runs down its body and extends abruptly into the lower lobe of its caudal fin. What truly sets them apart from other characins, however, is their peculiar swimming habit; they naturally rest and swim at a distinct 30-degree, tail-down angle.

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Is it right for your tank?

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Where Penguin Tetra comes from

Native range

Amazon Basin, Araguaia River Basin

Countries / regions

Brazil, Peru

Habitat

Slow-moving, heavily vegetated tributaries, streams, and flooded forests, often with tannin-stained water.

Primarily found in the upper Amazon basin in Peru and the Araguaia basin in Brazil.

Similar species

Oblique Tetra
Thayeria obliqua
Rummy-nose Tetra
Hemigrammus bleheri
Black Neon Tetra
Hyphessobrycon herbertaxelrodi
Diamond Tetra
Moenkhausia pittieri

We’re adding more full species guides as the catalogue grows.

Compatible tank mates

Reviewed guidance based on this species' recorded traits.

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Corydoras Catfish
Corydoras spp.
Peaceful, bottom-dwelling catfish that occupy a different area of the tank, preventing any competition for swimming space.
Great
Harlequin Rasbora
Trigonostigma heteromorpha
Equally peaceful, similarly sized shoaling fish that thrive in the same water parameters.
Great
Dwarf Cichlids
Apistogramma spp.
Peaceful bottom-to-mid dwelling cichlids that appreciate the active dither fish overhead.
Great
Betta Fish
Betta splendens
Penguin Tetras can be prone to fin-nipping if kept in too small a group, which poses a risk to long-finned tankmates like Bettas.
Compatible with caution
Oscar
Astronotus ocellatus
Large, predatory cichlids will easily view the slender Penguin Tetra as a food source.
Not recommended

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