An active schooling characin instantly recognizable by its bold black horizontal stripe that extends down into the lower half of the tail fin, and its unique, oblique (head-up) swimming posture. They are hardy and do well in community tanks, but must be kept in groups to prevent stress and fin-nipping behavior towards tank mates.
At a Glance
Tank Requirements
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Water Parameters
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Temperament & Compatibility
Available Varieties
Each variety inherits the species defaults above. Only differences are highlighted.
Standard
The standard wild-type form available in the aquarium trade. Must be kept in a school of at least 6 to diffuse their boisterous energy and prevent them from nipping the fins of slower-moving or long-finned tank mates.
Same care requirements as the base species
Also known as: Wild Type, Common
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🟢Ideal Tank MatesPenguin Tetra Care Guide Summary
The Penguin Tetra, scientifically known as Thayeria boehlkei, belongs to the Characins family group. Adults reach a maximum size of approximately 6 cm and have a fusiform body shape with a moderate growth rate. Classified as peaceful, this species primarily occupies the surface and mid-level zones of the aquarium and produces a low level of biological waste.
To thrive, the Penguin Tetra requires a freshwater only aquarium with a minimum volume of 75 litres and a tank length of at least 60 cm. Water temperature should be maintained between 22°C and 28°C, with a pH range of 5.5–7.5 and a general hardness of 2–15 dGH. A moderate water flow is preferred. An aquarium test kit can help you monitor these values.
The Penguin Tetra is a rewarding species to keep, provided its core environmental needs are met. The Penguin Tetra is typically available in one standard form.
Penguin Tetra Habitat Setup
When setting up an aquarium for the Penguin Tetra, a moderate water flow best suits their natural preferences. Because this species occupies the surface and mid-level zones, the aquarium layout should prioritise adequate surface area with floating cover to make them feel secure near the waterline and open swimming space in the centre of the tank for free movement. Useful additions include dense planting to provide cover, break sightlines, and reduce stress and floating plants to diffuse overhead light and create shaded areas. Keepers should note that a tight-fitting lid is essential, as this species is a known jumper.
Penguin Tetra Compatibility Notes
Classified as peaceful, the Penguin Tetra is a schooling species that feels most secure in a sizeable group, where natural shoaling behaviour reduces stress and brings out their best colours. When choosing tankmates, avoid housing with slow-moving or long-finned species that may become targets for fin nipping and their energetic swimming style may stress more sedentary or timid species. Selecting tankmates that favour different water layers from the surface and mid-level zones can help reduce competition and territorial overlap.
Frequently Asked Questions About Penguin Tetra
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Similar Species
Lemon Tetra
Hyphessobrycon pulchripinnis
A peaceful, deep-bodied schooling tetra known for its translucent yellow coloration and striking black and yellow fins. They are robust and active, making them an excellent choice for planted community aquariums. Their colors intensify significantly in a well-established tank with a dark substrate and proper schooling numbers.
Black Neon Tetra
Hyphessobrycon herbertaxelrodi
A peaceful, active schooling fish native to the Paraguay basin. Known for its striking contrast of a dark black lateral stripe underneath a glowing iridescent white/green-gold stripe. Excellent for community aquariums, particularly in planted setups or blackwater biotope tanks with subdued lighting.
Serpae Tetra
Hyphessobrycon eques
A striking, deep-red schooling fish known for its highly active nature. While hardy and beautiful, Serpae Tetras are notorious fin-nippers. This behavior is usually localized within their own pecking order if kept in large enough schools (8+), but they should never be housed with slow-moving or long-finned tank mates like Bettas, Angelfish, or Gouramis.
Emperor Tetra
Nematobrycon palmeri
A striking, robust schooling fish from Colombia. Unlike many tetras, they do not swim in a tight shoal, preferring to loosely associate while males stake out small territories to display to females. They feature a bold black lateral line and iridescent purple/blue hues.
Cardinal Tetra
Paracheirodon axelrodi
A stunning schooling fish native to the upper Orinoco and Rio Negro basins in South America. Famous for its brilliant iridescent blue line and a vivid red stripe that extends the full length of its body (distinguishing it from the Neon Tetra). They are strictly schooling fish that thrive in warm, acidic blackwater environments.
Black Skirt Tetra
Gymnocorymbus ternetzi
A very hardy, deep-bodied schooling tetra native to South America. They are incredibly popular for beginners but have a reputation as fin-nippers if kept in too small a group. A proper school disperses their internal bickering and largely prevents them from harassing other tank mates.