Redtail Penguin Tetra (Thayeria sp. "Rio Teles Pires")

The Redtail Penguin Tetra (Thayeria sp. "Rio Teles Pires") is collected from the Rio Teles Pires drainage in the southern Amazon Basin of Brazil. This region is home to a diverse network of forest streams, tributaries, and slow-moving river margins where dense vegetation shades the water throughout much of the year.

The water is typically soft, warm, and often lightly stained by tannins released from fallen leaves, branches, and other organic material. Sand, fine gravel, submerged roots, and driftwood create a complex underwater landscape that provides shelter while allowing schools of Redtail Penguin Tetras to move freely through the middle water column.

Seasonal rainfall plays an important role in shaping this habitat. During the wet season, rising water floods surrounding forests, creating an abundance of submerged structure and greatly expanding the available habitat. As water levels recede, fish return to permanent streams and channels, where they continue to feed on small aquatic invertebrates, insects, and other naturally available foods.

Although the Redtail Penguin Tetra adapts well to the home aquarium, it displays its most natural behavior in a mature aquarium that provides open swimming space alongside driftwood, live plants, and shaded areas that help recreate the feel of its native Amazonian environment.

Picture a mature Amazon-inspired aquarium where a school of Redtail Penguin Tetras glides effortlessly through open water between islands of lush aquatic plants. Dark driftwood branches reach upward from a bed of fine sand, while scattered leaves and seed pods soften the hardscape and create the natural appearance of a quiet forest stream. The contrast between the dark décor and the tetras' brilliant red tails allows every turn of the school to stand out.

Build the aquarium around open swimming space first, then frame that space with structure. Branching driftwood creates natural boundaries without restricting movement, while plants such as Amazon Swords, Cryptocorynes, and taller stem plants provide a soft backdrop rather than filling the center of the aquarium. Floating plants help diffuse bright lighting, encouraging the school to remain visible throughout the day instead of retreating into cover.

Complete the scene with Aquatic Arts Botanicals, such as the Botanical Combo Pack, Mixed Fruit Leaf Pack, Guava Leaves, Alder Cones, and Tannin Tea Bags. As these botanicals slowly condition the aquarium, they contribute to a more natural appearance while supporting biofilm, microbial life, and microfauna throughout the aquarium. The Redtail Penguin Tetras spend much of their time cruising the open water between these natural features, creating the impression of a living Amazon stream rather than simply swimming inside a glass box.

The Redtail Penguin Tetra is an opportunistic omnivore that feeds on a wide variety of small foods in nature, including aquatic insects, insect larvae, tiny crustaceans, zooplankton, and other microscopic prey. In the home aquarium, this species readily accepts a variety of prepared and frozen foods when offered a balanced diet.

A high-quality micro pellet or tropical flake should serve as the primary daily diet, supplemented several times each week with frozen foods such as Bloodworms, Daphnia, Cyclops, Mysis Shrimp, and Baby Brine Shrimp. Live foods can also be offered periodically to encourage natural feeding behaviors and help maintain excellent body condition.

Because Redtail Penguin Tetras are active midwater feeders, offer foods that remain suspended in the water column long enough for the entire school to feed. Feeding smaller portions two or three times per day is generally preferable to a single large feeding, helping reduce waste while allowing more natural feeding activity.

A varied diet not only supports long-term health but also helps these tetras develop their best coloration, maintain strong immune systems, and display the active schooling behavior that makes them such an enjoyable addition to the aquarium.

The Redtail Penguin Tetra is a peaceful schooling fish that does best with calm community species that will not intimidate, outcompete, or prey on it. Good tank mates should tolerate similar warm, soft to moderately hard water and allow the school to occupy the middle and upper portions of the aquarium without constant disruption.

Corydoras Catfish
Corydoras make excellent tank mates because they remain primarily along the bottom of the aquarium. This reduces competition for swimming space while adding activity to a different level of the tank.

Pencilfish
Pencilfish are peaceful, lightly built community fish that generally occupy the upper portions of the aquarium. Their calm behavior complements the more active schooling movement of the Redtail Penguin Tetra.

Hatchetfish
Hatchetfish spend most of their time near the surface, allowing Redtail Penguin Tetras to use the middle water column without crowding. A securely covered aquarium is essential because Hatchetfish are powerful jumpers.

Peaceful Corydoras-Sized Catfish and Small Plecos
Small Loricariid catfish and other peaceful bottom dwellers usually coexist well because they focus on surfaces, wood, and the lower aquarium rather than competing directly with the tetra school.

Peaceful Dwarf Cichlids
Calmer dwarf cichlids, including many Apistogramma species, can work well in a properly arranged aquarium. The tetras remain in open water while the cichlids establish territories closer to caves, wood, and the substrate. Adequate space and visual barriers are important during breeding.

Other Peaceful Tetras
Similarly sized tetras can create a lively community when each species is maintained in an appropriate school. Avoid overcrowding the middle water column with too many schooling species competing for the same space.

Peaceful Rasboras
Rasboras with similar care requirements are generally compatible because they share a peaceful temperament and are unlikely to harass or injure the Redtail Penguin Tetra.

Small Peaceful Rainbowfish
Smaller Rainbowfish may work in spacious aquariums, but they should not be so large or energetic that they intimidate the school or dominate feeding time.

Tank Mates to Avoid

Avoid large predatory fish that may view the Redtail Penguin Tetra as food. Aggressive cichlids, highly territorial species, and persistent fin nippers can prevent the school from feeding normally and may keep the fish in a constant state of stress.

Very boisterous or fast-feeding fish may also be poor companions because they can repeatedly outcompete the Redtail Penguin Tetras at mealtimes. Tank mates should be selected for compatible behavior, adult size, water requirements, and feeding style rather than appearance alone.

Yes, With Adult Shrimp

The Redtail Penguin Tetra is generally considered a good choice for community aquariums that include larger freshwater shrimp. Its small mouth and peaceful temperament make healthy adult Neocaridina Shrimp, Caridina Shrimp, Amano Shrimp, Bamboo Shrimp, Vampire Shrimp, and other similarly sized species suitable tank mates in most established aquariums.

Very small shrimplets, however, may be viewed as a natural food source if they venture into open water. This is common among most community fish and is not unique to the Redtail Penguin Tetra. Aquariums with dense mosses, fine-leaved plants, driftwood, botanicals, and mature biofilm provide excellent refuge for juvenile shrimp and greatly improve their survival rates.

Aquarists hoping to maximize shrimp reproduction should provide abundant cover and avoid relying on open aquascapes alone. In well-structured planted aquariums, many hobbyists successfully maintain thriving colonies of freshwater shrimp alongside schools of Redtail Penguin Tetras.

Difficulty: Moderate

Breeding Type: Egg Scattering

The Redtail Penguin Tetra is an egg-scattering species that deposits adhesive eggs among fine-leaved plants, spawning mops, mosses, and other dense vegetation. Like many South American tetras, adults provide no parental care and may consume both eggs and newly hatched fry if left together.

Successful breeding is most often achieved by conditioning a healthy group or compatible pair with a varied diet of live and frozen foods before introducing them to a separate breeding aquarium with soft, slightly acidic water. Dim lighting, spawning mops, Java Moss, or other fine-textured plants provide suitable locations for egg deposition.

After spawning, the adults should be removed to prevent predation on the eggs. Once the fry become free swimming, they require extremely small foods such as infusoria before graduating to freshly hatched Baby Brine Shrimp and other appropriately sized fry foods as they grow.

Because the Redtail Penguin Tetra is currently available primarily as a wild-collected species, captive breeding remains relatively uncommon compared to many other tetra species in the aquarium hobby.

Are Redtail Penguin Tetras good beginner fish?

Yes. Redtail Penguin Tetras are an excellent choice for beginner and intermediate aquarists who have a mature aquarium with stable water quality. They are peaceful, active, readily accept prepared foods, and adapt well to community aquariums when maintained in an appropriately sized school.

How many Redtail Penguin Tetras should I keep together?

Redtail Penguin Tetras should always be kept in a school. We recommend starting with at least six individuals, although groups of eight to twelve or more typically display more natural schooling behavior, greater confidence, and richer coloration.

Can Redtail Penguin Tetras live alone?

No. Redtail Penguin Tetras are naturally social fish that depend on the security of a school. Keeping a single fish often results in increased stress, reduced activity, and less natural behavior.

How large do Redtail Penguin Tetras get?

Adult Redtail Penguin Tetras typically reach about 2 to 2.5 inches in length. Their streamlined body allows them to remain graceful, active swimmers throughout their lives.

How long do Redtail Penguin Tetras live?

With excellent water quality, a varied diet, and consistent aquarium maintenance, Redtail Penguin Tetras commonly live five to eight years.

Are Redtail Penguin Tetras aggressive?

No. Redtail Penguin Tetras are peaceful community fish that spend most of their time schooling rather than establishing territories or harassing other aquarium inhabitants.

Do Redtail Penguin Tetras nip fins?

Redtail Penguin Tetras are not generally considered fin nippers. Like many schooling fish, however, they may occasionally investigate long-finned tank mates if maintained in groups that are too small. Keeping a proper school helps minimize this behavior.

Are Redtail Penguin Tetras shrimp safe?

Adult Neocaridina Shrimp, Caridina Shrimp, Amano Shrimp, Bamboo Shrimp, and Vampire Shrimp generally coexist well with Redtail Penguin Tetras. Newly hatched shrimplets, however, may be viewed as food. Dense mosses, driftwood, botanicals, and other cover greatly improve juvenile shrimp survival.

What fish make the best tank mates for Redtail Penguin Tetras?

Peaceful community fish that occupy different areas of the aquarium make the best companions. Corydoras Catfish, Pencilfish, Hatchetfish, peaceful dwarf cichlids, small plecos, peaceful rasboras, and similarly sized tetras all make excellent choices because they share comparable water requirements without competing aggressively for territory.

What should I avoid keeping with Redtail Penguin Tetras?

Avoid large predatory fish, aggressive cichlids, persistent fin nippers, and highly territorial species. Fish that are large enough to view Redtail Penguin Tetras as prey or aggressive enough to constantly chase them can prevent the school from feeding normally and lead to chronic stress.

What do Redtail Penguin Tetras eat?

Redtail Penguin Tetras are opportunistic omnivores that readily accept quality flakes, micro pellets, frozen foods, and live foods. A varied diet supports healthy growth, strong immune function, and vibrant coloration.

How often should I feed Redtail Penguin Tetras?

Feed small portions one to three times daily, offering only what the school can consume within a few minutes. Multiple smaller feedings more closely resemble their natural feeding behavior than one large meal.

Do Redtail Penguin Tetras need live food?

No. A quality prepared diet is sufficient for long-term success. Live and frozen foods are excellent supplements that encourage natural feeding behaviors and help condition fish for breeding.

Can Redtail Penguin Tetras live in a planted aquarium?

Yes. Redtail Penguin Tetras are exceptionally well suited for planted aquariums. Plants provide security, improve the overall appearance of the aquarium, and help create a more natural environment while still allowing open swimming areas.

Do Redtail Penguin Tetras like blackwater aquariums?

Yes. While they do not require blackwater conditions, Redtail Penguin Tetras thrive in aquariums that include driftwood, botanicals, and tannins. These features closely resemble the environments from which wild fish are collected and often encourage more natural behavior.

What water parameters do Redtail Penguin Tetras prefer?

Redtail Penguin Tetras do best in warm, clean, stable water with low to moderate flow. Stability is generally more important than chasing exact numbers, and regular maintenance is one of the biggest factors in long-term success.

Do Redtail Penguin Tetras jump?

Like many tetras, Redtail Penguin Tetras can jump when startled or during acclimation. A securely fitted aquarium lid is always recommended.

Can Redtail Penguin Tetras live with Angelfish?

Yes, in many community aquariums they can. Adult Angelfish usually coexist well with adult Redtail Penguin Tetras provided the aquarium is spacious and neither species is overcrowded. Very small tetras should not be housed with large Angelfish that may view them as prey.

Can Redtail Penguin Tetras live with Discus?

Yes. Redtail Penguin Tetras are frequently considered suitable companions for Discus because both species appreciate warm, clean water and peaceful surroundings. Their active schooling behavior also adds movement without disturbing the Discus.

Can Redtail Penguin Tetras be bred in the home aquarium?

Yes. Redtail Penguin Tetras are egg scatterers and can be bred in a dedicated spawning aquarium with soft water, fine-leaved plants or spawning mops, and conditioned adults. Removing the parents after spawning greatly improves egg survival.

How can I tell males from females?

Adult females are generally fuller-bodied, particularly when carrying eggs, while males often appear slightly slimmer. Differences are subtle and are usually easiest to observe when a healthy school has matured.

Why are they called Redtail Penguin Tetras?

The common name comes from the combination of the classic angled "penguin" stripe characteristic of the genus Thayeria and the distinctive red coloration of the tail that separates this species from the more familiar Penguin Tetra.

What makes the Redtail Penguin Tetra different from the common Penguin Tetra?

The Redtail Penguin Tetra is distinguished by its vivid red tail and represents an undescribed Thayeria species from the Rio Teles Pires drainage. While both share the characteristic penguin stripe and peaceful schooling behavior, the red tail gives this species a noticeably different appearance in the aquarium.

Are Redtail Penguin Tetras wild collected or tank bred?

The Redtail Penguin Tetra offered by Aquatic Arts is a wild-collected species from Brazil. Wild fish often display exceptional natural coloration and provide hobbyists with the opportunity to keep a species that remains relatively uncommon in the aquarium trade.

Would Aquatic Arts recommend Redtail Penguin Tetras for my aquarium?

If you're looking for a peaceful, active schooling fish that brings graceful movement and natural beauty to a planted community aquarium, the Redtail Penguin Tetra is an excellent choice. We especially recommend this species for aquarists who enjoy South American community aquariums with live plants, driftwood, and natural botanicals.

We stand behind the health and quality of every fish we offer. Each Redtail Penguin Tetra is carefully quarantined, observed, and conditioned before shipment to help ensure it arrives healthy, active, and ready to thrive in its new aquarium.

Every fish order ships in our Aquatic Arts Live Arrival Guarantee Box at no additional charge. Each shipment is professionally packed using insulated packaging and weather-appropriate heat or cold packs when necessary to help maintain safe temperatures throughout transit.

Every Redtail Penguin Tetra is backed by our 100% Live Arrival Guarantee. If your fish arrive with any issues, please complete our DOA Claim Form as soon as possible and include all required photographs and order information. This allows our Customer Support Team to review your claim and provide the fastest possible resolution.

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Best Fishes,

The Aquatic Arts Team