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Penguin Tetra Care: Everything You Need To Know

Penguin Tetra Care: Everything You Need To Know

In the mesmerizing world of tropical fishkeeping, few species capture the imagination quite like the Penguin Tetra. With their striking black and white patterns reminiscent of their namesake, these enchanting freshwater fish add a touch of elegance and grace to any aquarium.

To ensure the health and vitality of these peaceful fish, it is crucial to have a thorough understanding of their care requirements. This article covers everything you need to know about Penguin Tetras. You’ll learn about their temperament, tank set-up, and more, so you can raise Penguins at home. 

In this article, we’ll explore their natural habitat, discuss their ideal tank setup, delve into their dietary needs, and provide essential tips for maintaining their overall well-being. 

Penguin Tetra Overview and Natural Habitat

  • Common name: Penguin Tetra
  • Scientific name: Thayeria Boehlkei
  • Care level: Easy
  • Size:  2.4 inches (6 cm)
  • Lifespan: Five years
  • Temperament: Calm
  • Diet: Omnivore
  • Group size: Six
  • Minimum tank size: 20 gallons
  • Tank level: Mid-top
  • Water temperature: 73°-82° F (22-28°C)
  • Water pH levels: 6-8
  • Water hardness: 4-20 dGH

Penguin Tetras are one of the larger tetra species. The adults can grow up to 2.4 inches (6 cm), significantly longer than Neon Tetras. These fish are pale, with a thick black stripe running through the length of their bodies to the bottom fin on their tail.

The Penguin Tetra is native to South America and can be found in the Araguaia River in Brazil and the Amazon River basin in Peru. These rivers are very slow-moving and full of plants, which give the tetras plenty of hiding spaces.

Penguin Tetra Appearance and Size

Penguin Tetras have a unique appearance, so they’re easy to identify. They’re light tan or gold with a dark stripe that starts behind their gills and goes to the tip of the bottom half of their tail fin. Penguins also swim at a slight angle instead of remaining horizontal.

Many other tetra species generally grow to 1.5 inches (3.81 cm). Hence, at 2.4 inches (6 cm) on average, Penguin Tetras are larger than most of them.

Difference Between Males and Females

Penguin Tetras are nearly impossible to tell apart until they reach maturity. Once they become adults, the males are noticeably brighter and smaller than the females. 

The female Penguin Tetras also have a much rounder body shape, which can cause their stripe to appear slightly curved. Looking for that bend can help you tell them apart quickly.

Penguin Tetra Personality and Behavior

These tetras are very peaceful and prefer to live in a school of six or more. If there aren’t enough Penguin Tetras in your tank, they become stressed, defensive, and fearful of other fish. So, please ensure you have enough space for a group.

When they’re content, these tetras can be very playful and energetic. You’ll see them zooming around their tank, play-chasing each other, and exploring their decorations.

Penguin Tetras are the most active during the day and sleep at night. However, they usually only breed during the night.

Penguin Tetra Expected Lifespan

Penguin Tetras can live between three and five years as pets. Like many other fish species, their lifespan can be influenced by various factors, including their living conditions and the level of care they receive.

With the proper care and optimal living conditions, it is possible for them to live longer than five years and even reach eight years of age.

Penguin Tetra Care and Tank Set Up

Knowing the best tank setup for your Penguins will help you take good care of them. These fish prefer neutral, soft water. They also like filtered light, so you’ll want to include a lot of plants and decorations in their tanks.

Tank Size

Since Penguin Tetras are larger than many other tetras, the larger a tank you can get for them, the better. They love exploring and swimming in open waters, so you need to provide enough room for them to move freely.

If you only have a small school of Penguins in a tank, then a 20-gallon one should be enough. However, you might prefer having a 30-gallon tank to have more fish.

How Many Penguin Tetras Are Suitable for a 20-Gallon Tank?

Eight Penguin Tetras are suitable for a 20-gallon tank, using the one-inch (2.54 cm) of tetra per gallon rule. Since you need a minimum of six Penguins to form a school, a 20-gallon tank is a perfect size.

A 15-gallon tank is also suitable because it can hold six Penguin Tetras. However, I recommend still sizing up to 20 gallons, even if you only plan on keeping the smallest size school. Your fish will have plenty of room to swim that way.

Water Parameters

  • Water temperature: 73°-82° F (22-28°C)
  • Water pH levels: 6-8
  • Water hardness: 4-20 dGH

Penguin Tetras live in very slow-moving, slightly acidic to neutral, dark waters in the wild. Keeping their tank as close to their natural environment as possible will make your fish more comfortable.

Water Temperature

As tropical freshwater fish, Penguins like their water temperature between 73° and 82° F (22 and 28°C). Unless you keep your home very warm, you’ll need to use a tank heater to keep their water in that range.

Water pH Levels

Penguin Tetras prefer to live in neutral water, although they can survive in slightly acidic water. These fish are adaptable to different water conditions since most commercially sold fish are bred in captivity. It is, however, recommended to keep the pH level between 6 – 8 to prevent stress in your fish.

Unlike other tetra species that require more acidic water, Penguin Tetras require less adjustment to their water parameters, making them relatively easier to care for in terms of maintaining the ideal pH level for their well-being.

Water Hardness

Penguin Tetras aren’t picky when it comes to water hardness. They can survive in water between four and 20 dGH. 

If you’re keeping them in a tank with other tetras, you’ll want to ensure the water is soft enough for them. Penguin Tetras are fine as long as you remain within that range.

However, to breed your Penguins, you must keep the tank water very soft, under four dGH.

Water Current

In their natural environment, Penguin Tetras live in very slow-moving water. So, while they like a bit of a current, you don’t want to make it too strong.

These tetras are larger than others, so they can tolerate a slightly stronger current. However, they don’t enjoy it very much. It’s best to keep their water mostly still, with a very light flow to stir oxygen into it.

You’ll know that the current is too strong for your tetras if they only swim in the still portions of your tank.

What To Put in the Tank

Decorating your tank can be a lot of fun. I recommend planning a planted tank for your Penguin Tetras since it has more benefits. They’ll have more hiding places, and the plants can offer more oxygen and keep the water clean.


You don’t need to choose a specific substrate for your Penguins because they won’t bother it much. However, you will want to ensure it’s dark to better match what they’re used to in the wild.

Some good substrate options for Penguin Tetras include gravel, sand, and small pebbles. Although, you do want to make sure the substrate is compatible with the plants you choose.


When decorating a tank for Penguin Tetras, you want the sides of the aquarium to have plenty of plants and hiding spaces, with the middle open for them to swim freely.

Some great decorations include driftwood, stones, and caves. Having more objects in the tank can make your tetras feel much more secure since they have somewhere to flee if they feel threatened.

Ideal Plants

Penguin Tetras don’t like a lot of light, so you’ll want to add plenty of plants to help filter it out. 

Some of the best options include Java Fern, Anubias, and Amazon Swords. Adding Frogbit to one side of the aquarium can also create a shady space for your tetras to relax.

Java moss is also acceptable, and it will lower the pH of your tank. If you need to keep the water acidic for other fish in your community tanks.


In the wild, Penguin Tetras live in water with dense vegetation, so they prefer dimly lit surroundings to direct, bright light. So, you’ll need to use many plants to block it.

You’ll also want to turn the lights on their tank off at night. These tetras are active during the day, and leaving the light on overnight can disturb their circadian rhythm. 


You’ll likely need to add a water heater to their aquarium. Penguin Tetras must be in water temperatures of 73° to 82° F (22 to 28°C), which can be challenging to regulate without a heater.

Penguin Tetras dislike sudden changes in temperature. If the difference is drastic enough, it can be hazardous to them. So, many aquarists recommend using a heater that shuts off when it reaches a set temperature.


A simple, standard filter for your tank’s size is good enough for Penguin Tetras. The plants in the tank will also help to keep it clean. Adding a few shrimp will help, too, since they remove food waste from the water.

Plus, a filter should stir the water gently, providing a light water flow that your tetras enjoy.

Lastly, since you need to keep at least six of these tetras in your aquarium, having a filter will likely be necessary to keep the water clear.

Penguin Tetra Tank Mates

Penguin Tetras are very relaxed and can get along with many other fish. They won’t become aggressive unless you don’t have enough of them in the tank to form a school.

Some good tank mates for them include other tetras and rasboras. Adult shrimp are another excellent option, but the Penguins may try to eat ones that are small enough.

Tank Mates To Avoid

You don’t want to put Penguin Tetras with larger or more aggressive fish. Since they’re very peaceful, they can easily get bullied by bigger fish. For example, some cichlids can be too aggressive with Penguin Tetras.

Like many other tetras, Penguin Tetras will also chase and bite at long, flowing fins. So, don’t pair them with fish with a tail with those characteristics. 

Penguin Tetra Food and Diet

Penguin Tetras have relatively uncomplicated dietary requirements, making them pretty easy to feed. In their natural habitat, they feed on a diet consisting of insects, larvae, worms, crustaceans, and other small invertebrates.

They are omnivores and will readily accept a wide range of commercially available fish foods, including high-quality flakes and pellets specifically formulated for tropical fish. 

It is essential to provide a varied diet to ensure their nutritional needs are met. Supplementing their staple diet with frozen or live foods such as bloodworms, daphnia, brine shrimp, or small insects will add excitement to their meals and provide essential proteins.

You can also offer them occasional treats like finely chopped vegetables, such as spinach or blanched peas, which can provide them with a source of fiber and essential vitamins.

It is important to feed them small, frequent meals rather than a large quantity all at once, as this mimics their natural feeding behavior. I recommend 2 – 3 times a day.

Overfeeding should be avoided to prevent issues such as obesity and water quality problems. Observing their feeding habits and adjusting the quantity and frequency of their meals accordingly will help ensure a healthy and well-balanced diet for your Penguin Tetras.

Breeding Penguin Tetras

While these fish can be bred in a home aquarium, it does require some specific conditions and attention to detail.

Firstly, it is important to provide the ideal breeding environment. A separate breeding tank or a well-planted section within the main aquarium can be set up. The tank should be equipped with fine-leaved plants, such as Java moss or spawning mops, where the tetras can lay their eggs. 

Given the opportunity, adults will eat the eggs. You can place a layer of marbles or mesh at the bottom of the tank to prevent them from reaching the eggs and eating them.

To encourage breeding behavior, it is beneficial to maintain a stable and slightly elevated temperature in the breeding tank, around 78-80°F (25-27°C). The water should be soft and slightly acidic, replicating their natural habitat. 

Regular water changes and a well-functioning filtration system are essential to maintain optimal water quality.

Penguin Tetras Common Health Issues

You’ll need to watch out for some health issues concerning Penguin Tetras. Keeping them happy and healthy will prevent most of them, so avoid stress in your fish.

That said, Penguin Tetras are very hardy fish, making it easy to prevent illness.

Neon Tetra Disease (NTD)

Neon Tetra Disease, or NTD, is an illness common among tetras. It can impact any tetra, including Penguins.

The disease is caused by parasites that target the muscles and sometimes organs in the fish. It spreads quickly and is fatal.

NTD Symptoms

Fish with NTD will start becoming restless and swimming strangely. They also lose their vibrant colors and may become bloated.

The tetra will also start eating less and may have white lumps on its body. Sometimes, their spine forms a curve.

NTD Treatment

Unfortunately, there is no treatment for NTD. All you can do is remove infected fish from the tank to prevent it from spreading further.

Make sure that the fish don’t have false Neon Tetra Disease after quarantining them. False NTD is actually columnaris, which can be cured with antibiotics. They have very similar symptoms, so it’s best to monitor the fish after it’s in a separate tank.

NTD Prevention

You can prevent NTD by not introducing tetras to the tank that have it. Quarantine all new fish for a few weeks before putting them in your community tanks.

If you notice any sick fish in your tank, separate them immediately. 

Swim Bladder Disorder

Swim bladder disorder can be common among Penguin Tetras. It’s when the swim bladder of a fish stops working correctly due to infection or stress.

Swim Bladder Disorder Symptoms

Fish with swim bladder disorder may:

  • Swim upside down or sideways
  • Have a curved back or round belly
  • Struggle to swim normally
  • Sink to the bottom of their tank

Swim Bladder Disorder Treatment

Swim bladder problems can be challenging to treat since they have many causes. Eating too fast or gulping air can distend the fish’s stomach and push on the swim bladder. Infections can also cause issues.

You can usually treat the tetra with antibiotics if it’s from an infection.

However, if it’s from another cause, you can add small amounts of aquarium salt to the water and keep the temperature high. Do your best to keep the tank as clean as possible.

If the fish can’t eat due to being unable to swim, you must hand-feed it.

Swim Bladder Disorder Prevention

Poor water conditions lead to stress, making the fish’s infection easier. So, you’ll want to keep the water at the best parameters for Penguin Tetras to prevent swim bladder problems.

Feeding high-quality food and soaking dry food before feeding can also help. Then, make sure you aren’t overfeeding your fish.

Are Penguin Tetras Right for You?

Penguin Tetras are excellent fish for beginners. They’re incredibly hardy and can survive in a variety of water conditions.

They also make great tank mates, so many people interested in community tanks choose them. You’re sure to love how active these fish are.

Penguin Tetra FAQs

Can You Mix Neon and Penguin Tetra?

You can mix Neon and Penguin Tetras. Neither of these fish are aggressive, and they get along well. Many people like combining them because the neutral colors of the Penguins can make the Neons stand out much more.

The Penguin Tetras can also live in various water conditions, making it easy to match them to the Neons’ parameters.

Are Penguin Tetras Aggressive?

Penguin Tetras are not aggressive. They’re calm fish that prefer to live in tanks with lots of hiding spots since they’re usually prey to bigger fish.

You can keep your Penguin Tetras with various other non-aggressive species.

Can Penguin Tetras Live Alone?

Penguin Tetras can’t live alone. They need to live in schools of six or more. If you don’t have enough in a tank, they become stressed and will always hide. They’ll get sick easier too.

So, getting a large enough tank to hold a whole school of these tetras is essential.

Wrapping Up

Penguin Tetras are undeniably fantastic fish for anyone to raise, whether you are a beginner or an experienced aquarist. Their calm demeanor and energetic nature make them a delightful addition to any aquarium. These fish exhibit a peaceful temperament, making them compatible with a wide range of tank mates.

By maintaining suitable water conditions, such as keeping the pH level between 6 – 8 and ensuring clean and properly filtered water, you can create a comfortable and healthy environment for your Penguin Tetras.

I’m Elle, the founder of FishHQ. I created this website to share knowledge, tips, and inspiration for beginner hobbyists to help them create a healthy, happy, and vibrant environment for their fish to thrive. Read more...