Penguin Tetra (Thayeria boehlkei) Care guide – Size, Life Span, Tank Mates, Breeding

penguin tetra

The complete information about the penguin tetra fish

The penguin tetra fish has a peculiar swim with its body tilted. If you are interested in acquiring one, do not hesitate to continue reading to know all its characteristics.

Scientific NameThayeria boehlkei
Other NamesHockey Stick Tetra and Blackline Tetra
OriginsSouth America
Aquarium LevelMiddle – Top
DifficultyBeginner – Intermediate
Best kept asGroups 5+
Lifespan3 – 5
Maximum Sizeup to 6 cm

What is the penguin tetra fish like?

This fish has an elongated and very thin shape. Its body is silver in colour and in the centre, it has a black line that runs from the operculum to the tail fin. On the anal fin, there is a thin white line that runs along the entire front edge.

The penguin tetra fish is very similar to the  Thayeria obliqua, differing only in the black line that the penguin tetra fish have, whose end is blurred on the fish’s back.

Penguin Tetra fish can reach an average length of  6 or 7 centimetres. The difference between males and females is that the female is fatter than the male penguin tetra fish. Sometimes this difference should not be seen with the naked eye, since sometimes males and females are the same sizes.

Other information about this family of fish

Penguin Tetra fish live in areas covered with vegetation that have very calm waters. Despite having a great swim, they are fish, like to stay still when they are comfortable in their habitat. In addition, penguin tetra fish have a very particular swim; they swim in an oblique position.

It is very typical to find them in the waters of the Amazons in Peru or in Brazil, in the  Araguaia River. They live at a temperature of 26 and 28 degrees and especially in soft and acidic waters.

Its behaviour with the rest of the fish is very calm, without disturbing others. They can chase each other, but it does not carry any danger because the penguin tetra fish is not aggressive. They are known to be bottom fish in the aquarium, thanks to their tranquillity compared to other animals.

The penguin tetra fish belongs to the Characidae or characids family, and its scientific name is Thayeria Boehlkei. The first known import of this fish to other countries in the world is from 1935.

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Feeding the penguin tetra fish

All fish need a specific diet. Although the penguin tetra fish does not need great care, it needs a good diet based on live and frozen animals and processed foods.

Meal hours

Like any fish that lives in captivity, they must have a meal schedule that keeps them energized during the day and at night. This schedule can be divided into two, three or four times during the day. Providing you at all times a type of food adapted to your needs and with a recommended amount.

Penguin Tetra fish can find food at the bottom. To avoid overfeeding, we must always give him the exact food, or clean the bottom of the aquarium regularly.

The best times for the penguin tetra fish to feed is in the morning. They are lovers of tranquillity and also of resting when darkness arrives. Feeding him in the morning will give him the necessary dose of energy so that he can be an active fish during the day.

We can also feed him when night falls, so he can swim before he begins his rest.

Food for the penguin tetra fish

The penguin tetra fish is a carnivorous and omnivorous animal. He likes to eat all kinds of food and especially small insects as well as frozen food.

Live food is his favourite and provides great nutrients. However, we must take care of the abuse of this type of food because it can also cause diseases to the penguin tetra fish. The most common are daphnia or also known as water fleas, and mosquito larvae.

The frozen food can be brine shrimp or tubifex. With this kind of food we will be providing the fish with the same nutrients as life food, but preventing them from catching diseases that live prey may have.

Dry food is another variety of food that we give to penguintetra fish, through scales, flakes, bars or granules. It is possible to find it with algae or with the crustacean.

They also eat commercially processed foods that we can buy at any pet store.

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Penguin Tetra fish diseases

Whether living in the wild or in captivity, all fish can suffer diseases that can kill them. In the case of having penguin tetra fish in our aquarium, we must be vigilant and observe it to make sure it is in good health.

How to know that my fish is healthy?

There are so many diseases in the animal kingdom that many times they can come with symptoms that can be seen with the naked eye, but many times we must be very aware of the behaviour of the fish to discover that it is suffering from some type of disease.

The most obvious thing to see that our penguin tetra fish is not in good health is its strange behaviour, among which we can find a strange or slow way of swimming, spending a lot of time on the surface, or barely moving from a place.

Regarding eating time, we can see if the penguin tetra fish in the aquarium eat normally or, however, most of the food ends up on the bottom without being digested. Or the opposite case, if we see a fish that is too big, we will also be facing a health problem for the fish.

fish diseases

The most common diseases come from excess oxygen, insufficient oxygen, or an inappropriate temperature for penguin tetra fish. On these three occasions, we are talking about diseases caused by an external condition that we must quickly solve by returning to the appropriate values ​​for the penguin tetra fish’s life.

Costiasis is a disease that is spread by a parasite manifesting itself in spots on the penguin tetra fish’s body. To treat it, we must put the sick animal in water with drops of formalin and add more drops every minute, for 10 minutes.

Due to the water, we can infect penguin tetra fish with diseases due to fungi that can arise as a result of poor cleaning of the aquarium. These fungi do not attack animals, but they can infect their wounds gradually invading their entire body until they reach death.

The behaviour of the penguin tetra fish

These animals are very calm fish, and their character is very peaceful. If you are looking to fill your aquarium, do not hesitate to add penguin tetra fish.

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The behaviour of penguin tetra fish

This class of fish has lived for many years in the wild. But after the first importation to live in captivity, many have wanted to place the penguin tetra fish in their aquarium with other fish, always with similar behaviour and sizes to avoid misfortunes between them.

But for many, the experience of the penguin tetra fish goes further, and when you enjoy it in your fish tank, you discover that they are very calm and even cowardly fish, since they will hide in a dark place if they do not have other fish of their own. The family next to him.

To enjoy the penguin tetra fish, we must always keep them in a group with at least seven specimens. The aquarium should be more than half a meter long and have a dark floor. We will also have to place plants so that they can rest and that will serve to filter the light because they are fish that do not like to be exposed very much.

In addition, we must always cover the aquarium because penguin tetra fish are known for their agility to jump and could get out of the water.

Other data on your behaviour

Penguin Tetra fish do not usually attack other fish even though they may be annoyed by their fast swimming. These animals are very calm and will normally never attack other fish. They will prefer to hide to avoid any danger than to face the other animals in the aquarium.

But it is recommended that we always have penguin tetra fish with other animals of similar appearance and behaviour because ultimately each fish may have exceptions in behaviour. When the tetra penguin fish goes with others of the same species, it will feel more protected and in a company so it will not have the need to disturb others.

The moment we see that our penguin tetra fish tries to attack others in the tank, we must immediately separate it to prevent some of the two from getting hurt.

Caring for the penguin tetra fish

Simple to care for, but still all fish need some basic care to offer the best life expectancy in the aquarium. Let’s know the details that will make your penguin tetra fish, a long-lasting and happy fish.

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Basic care for penguin tetra fish

Penguin Tetra fish are very easy to keep. This type of fish hardly needs care because they are very independent fish that hardly need anything to live their life peacefully.

We have to offer the only care that each day he receives the daily dose of food for all the penguin fish that we have in the aquarium. It is also important to provide the ideal temperature that they can withstand. This temperate is from 26 to 28 degrees. However, they are not fish that cannot live above or below it.

And the last advice that we offer you so that your tetra penguin fish is happy in the aquarium is that it can enjoy a dim light, almost poor for this we can place different spaces where it can hide and enjoy the darkness whenever they want.

As mentioned above, the penguin tetra fish is a very simple fish to have, breed, and extend its life expectancy with such basic care that it will hardly take time.

A large fish tank for a quiet swim

The tetra fish is a great swimmer, and it shows it by its speed and by spending a large part of the day swimming from one place to another. Although they love to swim, on many occasions, you can find them resting. He also simply likes to relax and drift with the water at times.

The penguin fish will always be annoying the other fish, but they will not be in danger since the penguin tetra fish is a very peaceful animal that likes to chase the other fish in the form of a game. But it doesn’t mean I’m going to attack them.

So that you can enjoy your swim, it is recommended that you have a large water tank where you can go from one place to another without obstacles.


Tips to get our penguin tetra fish to reproduce successfully. Keep reading and put into practice all these tricks to have offspring of this fish so popular for aquariums. They are ideal for living in captivity thanks to their tranquillity.

Tips for Playback

The first step we will do is to lower the pH values to 6.5 and maintain a temperature of 25 degrees in the aquarium where we will put our penguin tetra fish to reproduce.

These fish need little light to spawn. We will proceed to cover all with cardboard or other material, leaving only the upper part uncovered.

Luckily, penguintetra fish will not eat the eggs once they are laid, so there is no need for a rack. Once we release the couple inside the aquarium where we will have the young, both will need a few days to adapt to the new habitat.

After these days, the laying of eggs will take place during the afternoon and very close to the surface. The male will try to conquer the female until it spawns. Once the eggs have been released, we will remove the parents from the aquarium and remove a large part of the water.

The young of the penguintetra fish are born.

After 12 hours, the first larvae will hatch and stay in the darkest places in the water tank. In the bottom of the aquarium, the eggs that have not been fertilized will remain. They must be extracted through a fine tube.

From the fourth day after the penguin tetra fish have been born, the fry will be able to swim freely. From now on, we will begin to give it a little light by removing some cardboard or the material that we have used to cover the aquarium. We will also begin to feed them paramecia on a constant basis, to prevent them from starving.

When three weeks have passed since the fry began to hatch, we should move them to a larger place. We will also begin to change the food for brine shrimp nauplii, and finally, we will proceed to uncover the aquarium so that it receives natural light and they get used to their new life.

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