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.
Penguin Tetra At a Glance
Penguin Tetra Tank Requirements
Will Penguin Tetra fit in your tank?
Care guides tell you what Penguin Tetra needs, the next question is whether your tank can safely provide it. Test Penguin Tetra against your tank size, maintenance needs, and the fish you already keep before you buy.
Penguin Tetra Water Parameters
Penguin Tetra Temperament & Compatibility
Penguin Tetra 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
Penguin 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.
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.
Who Penguin Tetra Is Actually For
Penguin Tetra is best for a fishkeeper who wants a species that can settle into a calmer community setup and can provide a keeper who can commit to a proper group of at least 6. It makes the most sense for a hobbyist who will actually build around its needs, especially plants.
The most common mistake is buying Penguin Tetra for looks first and only later discovering how its adult size, behavior, or bioload changes the whole tank plan. Another frequent problem is underestimating its social needs. A token pair or trio often behaves very differently from a real group.
Penguin Tetra Recommended Tank Sizes
Standard aquarium sizes that meet the minimum volume and length requirements for Penguin Tetra.
20 Gallon High
20 Gallon Long
29 Gallon Standard
30 Gallon Breeder
36 Gallon Bowfront
40 Gallon Breeder
Show 17 more tank sizes
Frequently Asked Questions About Penguin Tetra
How big does Penguin Tetra get?
Penguin Tetra (Thayeria boehlkei) typically reaches a maximum adult size of approximately 6 cm. They have a fusiform body shape and a moderate growth rate.
What tank size does Penguin Tetra need?
A minimum aquarium volume of 75 litres and a tank length of at least 60 cm are recommended for Penguin Tetra. This ensures enough swimming space and helps maintain stable water conditions.
What water parameters does Penguin Tetra need?
Penguin Tetra thrives in freshwater only conditions with a temperature range of 22–28°C, a pH between 5.5 and 7.5, and a general hardness of 2–15 dGH. A moderate water flow is preferred.
Is Penguin Tetra peaceful or aggressive?
Penguin Tetra is classified as peaceful with an aggression score of 2 out of 10. They are generally well-suited to peaceful community tanks.
How many Penguin Tetra should be kept together?
Penguin Tetra is a schooling species and should be kept in groups of at least 6. Larger groups help distribute aggression and encourage natural schooling behaviour.
Does Penguin Tetra have any special tank requirements?
Yes. Penguin Tetra benefits from plants - densely covered and plants - floating in the aquarium. These features help replicate their natural habitat and promote overall health and well-being.
Does Penguin Tetra need a lid on the tank?
Yes. Penguin Tetra is a known jumper, and a tight-fitting lid or cover is essential to prevent escape. Even a small gap can be enough for a determined fish to leap out.
Useful setup supplies
We may earn from qualifying purchases
Guidarium Editorial Desk
Reviewed against Guidarium care, stocking, and compatibility standards. Read the editorial policy.
- Last reviewed
- April 28, 2026
- Last updated
- April 28, 2026
- Issues or corrections?
- Contact the editorial team
Top Tank Mates for Penguin Tetra
These fish are strong compatibility matches for Penguin Tetra based on water preferences, temperament, adult size, and tank behavior.
Spotted Hillstream Loach
Gastromyzon punctulatus
Ideal Tank MatesTrapdoor Snail
Cipangopaludina chinensis
Ideal Tank MatesWhite Cheeked Goby
Rhinogobius duospilus
Ideal Tank MatesReticulated Stingray (Teacup Ray)
Potamotrygon orbignyi
Ideal Tank MatesTandanus Catfish
Tandanus tandanus
Ideal Tank MatesSkunk Cory
Corydoras arcuatus
Ideal Tank MatesPlants That Suit Penguin Tetra
These plants pair well with Penguin Tetra based on shared water preferences, layout fit, and how likely they are to hold up in the same aquarium.
Afzel's Anubias
Anubias afzelii
Amazon Sword
Echinodorus amazonicus
Anacharis
Egeria densa
Anubias Barteri
Anubias barteri
Baby Tears
Lindernia rotundifolia
Balansae
Cryptocoryne crispatula
Fish Similar to Penguin Tetra
Glass Bloodfin Tetra
Prionobrama filigera
A highly active, schooling characin characterized by its translucent body and striking blood-red anal fin. They are peaceful but exceptionally fast-moving, requiring plenty of open horizontal swimming space in the upper levels of the aquarium. They are known to be skilled jumpers, making a tight-fitting lid mandatory.
Panda Tetra
Aphyocharax paraguayensis
A small, highly active, and strikingly marked characin native to the Paraguay River basin. Known as the Panda or Dawn Tetra, it features a metallic silver body with distinctive black and white markings on its tail and anal fins. While beautiful and hardy, they are notorious fin-nippers. They must be kept in larger schools to disperse aggression and should never be housed with slow-moving or long-finned fish (like Bettas or Angelfish).
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.
Head and Tail Light Tetra
Hemigrammus ocellifer
A peaceful, schooling characin named for the reflective copper/gold spots on its head and the base of its tail. These 'lights' evolved to help the school stay together in the dark, tannin-stained waters of the Amazon basin. They are hardy, active, and make excellent community fish for planted aquariums.
Bloodfin Tetra
Aphyocharax anisitsi
An extremely hardy and energetic schooling fish characterized by its silver body and striking bright red fins. As exceptionally active swimmers, they require plenty of horizontal swimming space. They are very adaptable to temperature and water parameters, making them a fantastic choice for beginners. Must be kept in groups to curb minor fin-nipping tendencies.
Rosy Finned Tetra
Hyphessobrycon rosaceus
A beautiful, deep-bodied tetra known for its reddish-pink hue and striking dorsal fin, which features a prominent black patch and white tip. They are peaceful, active schooling fish that thrive in heavily planted tanks with slightly acidic, soft water. Males frequently engage in harmless mock-battles by flaring their fins to establish hierarchy.