Penguin Tetra Stats InfographicThe Penguin Tetra, also known as thayeria boehlkei, is a popular member of the tetra freshwater fish species. Like its cousins, the Cardinal and Neon Tetra, the Penguin Tetra is kept for its attractive pattern, gentle nature, and wide availability. Schools of Penguin Tetra contrast to colorful fish in freshwater aquariums.

Tetras are one of the first species new aquarium keepers explore. They are available through most fish supply outlets and are not an expensive species to acquire or replace.

Once keepers have learned Penguin Tetras, the move up to larger, more colorful, and complex species is very manageable solo or mixed species tanks.

Penguin Tetra Stats

Listed tank sizes are the minimum

Size: Up to 2 1/2 inches (8 cm)
Tank: 24 inches
Strata: Top, middle
PH: 5.5 to 7.0
Hardness: Soft to hard dh range 4-20
Temperature: 73° to 82° F (22-28°C)
Order: Cypriniformes
Suborder: Characoidei
Family: Characidae
Genera: Thayeria

Origin and Appearance

Penguin tetra fishPenguin Tetras are one of many thousands of species of collectible fish that come from South America. They are a social, schooling species that is found extensively in the Amazon Basin from Peru into Western Brazil. The species prefers slow-moving waters and forms large schools.

Like many tetra species, the Penguin Tetra moves back and forth from the river to the flood lands during the rainy season for breeding and shelter. Penguin Tetras prefer this highly tannic water because of the heavy amounts of rotting vegetation that give it a dark color, almost like coffee.

It is in these low-light waters that the Penguin Tetra can be at its most vivid pattern. As floodwaters recede, the Penguin Tetra follow them back to their normal river habitats.

The Penguin Tetra is not brightly colored. What makes it stand out is the vivid black stripe running the length of its golden body all the way to the end of the lower lobe of its tail. This distinctive pattern gives the Penguin Tetra its other names of Black Stripe Tetra and Hockey Stick Tetra.

In well-kept environments, the Penguin Tetra size can reach up to 2.5 inches, making it one of the larger members of the tetra species. In the wild, the fish is relatively short-lived. In aquariums, the Penguin Tetra lifespan is up to 5 years.

Males and females have slightly different body shapes. As with other larger tetras, the female Penguin Tetra is the larger and stockier of the two. The difference in appearance becomes most noticeable when the species are preparing to spawn. The females will develop very pronounced round bellies.

As a social fish, the Penguin Tetra does best in groupings of 6 or 8 fish.

Penguin Tetra Care Guide

The penguin tetra fishThe Penguin Tetra is considered an easy-care species that do not require enormous aquariums or elaborate water conditioning systems. The same setup used for most tetra species will work for Penguin Tetra. That is water temperature and quality that closely mimic their native environment.

The ideal Penguin Tetra water temperature is 73° to 82° F (22-28°C). Keepers should maintain a water hardness of 5.5 to 7.0 and a pH of 4.0 to 20.0.

A 20-gallon tank is a good size for an Amazon species display and will support 8 or so Penguin Tetra and a few peaceful tankmates.

A standard filtration sized to match your aquarium is sufficient to maintain a light water flow and acceptable oxygen levels. Underground filtration systems work well for this purpose. The Penguin Tetra is sensitive to ammonia and nitrogen in the water, so a system that keeps the water well filtered is important.

Changing out a third of the water once a week is a good idea with this species. When Penguin Tetra spawns, the male can release so much milt that the water gets cloudy and will smell. A water change at this time is mandatory to keep all fish species in the aquarium healthy.

Since the species spends a large portion of its time in flooded forestland, Penguin Tetra thrives in tanks with natural or plants. A good planning strategy is to place vegetation heavily on the sides and back, leaving the central portion of the aquarium free for the Penguin Tetra to swim about.

Rooted plants give Cardinal Tetra something to explore and hide in when they are not darting about. Species such as Guppy Grass are a good habitat for Penguin Tetra eggs when they spawn.

Providing dim light to imitate the dark water conditions of their river environments cues the Penguin Tetra to shine their most vivid. You can add sticks, rocks, and similar structures for bottom variety and tank mate habitat.

A good, adjustable light and heating system are recommended for Penguin Tetra care and maintenance. Adjustable lights help imitate day and night. This cycle is important for any living plants you may have in the aquarium. A good heater will help maintain the water in the preferred temperature range. Penguin Tetras are quite intolerant of water temperature changes.

When water conditions are not ideal, Penguin Tetra can weaken and become susceptible to a variety of naturally occurring or introduced illnesses. One of the most common illnesses is neon tetra disease. Neon tetra disease is a prevalent ailment in tetra species. Named after the first species, it was identified in; neon tetra disease is a parasitic infection that first cripples, then kills the fish. It can spread rapidly.

The only way to prevent the introduction of neon tetra disease to an aquarium is to quarantine any new additions for up to two weeks before introducing them to the tank. Try to purchase fish in person and visually select healthy specimens from a reseller who will guarantee their quality. If you do purchase aquarium fish online, be sure the reseller will guarantee their fish for at least 30 days.

Tank Mates

The Penguin Tetra is a peaceful tank mate to most Amazon tetra and other small species. Its only predilection is being a fin nipper to slow-moving species.

A list of species that meet the needs for Penguin Tetra compatibility include:

Species such as danios, guppies, and rasboras make good tank mates because they are small, peaceful fish and don’t have a big impact on the bio-load of the tank. A few small catfish or specimens such as compatible snails also help balance out a tank.

While it may be tempting to introduce larger species, even semi-aggressive fish can harass or dine on tetras. At a minimum, avoid adding species that can fit a Penguin Tetra or other tank mates in its mouth.


Penguin Tetras are not difficult to breed. In most cases, they will do so without any prompting from you. Breeding can be encouraged by increasing the ratio of live foods such as brine shrimp or bloodworms to flake or pelletized foods.

If you observe your Penguin Tetra, you will see signs they are preparing to spawn. The males will begin chasing females around the tank, and the females will develop large, round bellies full of eggs.

The females will lay eggs over vegetation. Male Penguin Tetra fertilizes the eggs very heavily. After this has occurred, the tank water will need to be changed as Penguin Tetra sperm will foul the water for all species.

The eggs hatch in 24 hours or less. Most Penguin Tetra hatches are prolific, and an initial brood of as many as a thousand fry are possible in larger aquariums.

Penguin Tetra fry will feed as soon as they are hatched. Wonderful flakes or ground pellets are ideal starting foods. The Penguin Tetra growth rate is quite rapid. Fish can reach over an inch in a month.


Penguin Tetras are not fussy and will accept most anything offered. The species is happy with frozen, freeze-dried, or live food, and a mix of offerings keeps them from getting turned off by a mono food type.

Good meal choices include:

  • Tetra flake food
  • Tetra small pellets
  • Bloodworms
  • Brine shrimp
  • Daphnia
  • Tubifex

Feeding once a day in the morning or evening is fine but try to limit how much food is put into the tank so that the actual feeding takes no more than three or four minutes. This prevents overeating, which can lead to other illnesses. You can tell your Penguin Tetra are getting too much feed if their stomachs start to appear bulged.


  • Penguin tetra known as thayeria boehlkei fishPenguin Tetras are small, beautiful fish from the Amazon River basin.
  • Controlling water conditions is key to the successful long-term care of the species.
  • The best way to display Penguin Tetra is in a dimly lit aquarium with plenty of perimeter plants and vegetation.
  • Small, peaceful fish from the same river systems make ideal tank mates for Penguin Tetra.
  • Quarantine new tank mates for at least two weeks prior to introduction to ensure they do not carry neon tetra disease into your aquarium.
  • You should remove ill or dead fish from the aquarium quickly.
  • Penguin Tetra will readily breed in captivity.
  • Cardinal Tetras are not fussy eaters.

Aquarium keepers of all experience levels have Penguin Tetra displays for the beauty and activity they add to the tank. Whether you are new to the hobby or looking for something new, building out a South American Rainforest tank with Penguin Tetra and tank mates will provide a visually pleasing and rewarding keeper experience.

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