Are Penguin Tetras Aggressive?

Penguin tetras originate from South America living in countries such as Brazil, Colombia, Guyana, Peru and Venezuela. They are a freshwater fish species which is popular among aquarists. If you are thinking about adding them to a community tank you may well be wondering “are penguin tetras aggressive?” Penguin tetras are a calm and peaceful species of fish ideally suited to a community tank. They are a schooling fish and do better when kept in groups. If they are not kept in sufficient numbers they can display more aggressive behavior than normal, which usually takes the form of fin nipping.

So, Are Penguin Tetras Fin Nippers?

I wouldn’t class penguin tetras as “fin nippers” exactly. Although they will nip at fins on occasion this is usually as a result of feeling stressed and vulnerable due a lack of numbers. If there is not enough of them in their school, penguin tetras often start to nip at fins of other fish as a sort of pre-emptive defense mechanism. If kept in a large enough school of around 8-12 (or more) individuals they won’t usually display this behavior and are more than likely to get on with the other fish in the tank.

Are Penguin Tetras Territorial?

If your penguin tetras are fighting with each other it’s likely down to one of two things – unsuitable conditions or they are displaying mating behavior.

Penguin tetras are schooling fish and feel most comfortable in larger numbers if there are too few of them in their school this can heighten their aggressiveness towards other fish and also towards each other. Penguin tetras also require space as they are an active fish so if you have a school of penguin tetras in a tank that’s too small for them this may also cause them stress which could lead to aggression. If they are underfed, if they are ill, if the water condition is not right for them could all lead to stress, aggression and fighting.

There is also a chance that any fighting behavior you are witnessing is down to mating. It is quite common for male penguin tetras to harass and chase females in a bid to mate with them. This behavior tends to be more severe if there are quite a few more males than females in the tank as the males will be in competition with each other and there are fewer females to be the focus of the males’ attention!

Tank Size For Penguin Tetras

Penguin tetras are a shoaling fish and thrive when kept in groups of 8 plus. As with most species you should always go for the biggest tank possible, so that your fish have plenty of room to swim around etc. It is advised that you use an aquarium of at least 20 gallons (and preferably more) if you want to keep penguin tetras as they do not react well to being squeezed into small tanks.

Water Conditions For Penguin Tetras

For those who are new to keeping fish, it’s important to remember that penguin tetras like all other fish require pristine water conditions and the correct equipment such as filters, heaters and test kits alongside the right food to keep them happy and healthy. If they live in poor conditions these peaceful little fishes will become stressed and this can lead to them acting out character – fin nipping etc

Penguin tetras are very active swimmers so it is important that you keep the aquarium well-maintained as they produce a lot of waste for such small fish. It is recommended that penguin tetras have regular water changes every week, but if you don’t want to do more than 20% per week then at least perform a 10% change on a weekly basis. They prefer neutral hard water conditions (pH 7 or slightly higher) and temperatures between 72–82 degrees Fahrenheit, although they will tolerate temperatures slightly lower but not higher.

Are Penguin Tetras Good For Beginners?

Yes, they are! Penguin tetras are a great choice for beginner aquarists because they aren’t too demanding when it comes to care and maintenance. They don’t require huge tanks and don’t grow too large (about 3 inches), so a 20 gallon tank would be sufficient enough for a school of around 8 penguin tetras.

They are very active fish that like swimming space but are not overly fussy about what they swim in. They are hardy fish that can tolerate most water conditions and although they prefer a pH level of around 7, they will live comfortably in slightly acidic to neutral water.

As with many other species, it is important not to understock your aquarium as this increases the risk of fin nipping and aggression between fish. It’s important to remember that as with most species you should never treat them as ‘just one more fish’ and add just one or two penguin tetras into a tank thinking that they’re small enough to put up with cramped conditions – if you want them to thrive then give them the space and care which they deserve!

Penguin Tetra Tank Mates

The best tank mates for penguin tetras are other calm species such as glowlight tetras, dwarf corydoras, rasboras, serpae tetra and neon tetra. They can live compatibly with small freshwater shrimp if you keep them in a suitably sized aquarium – usually around 20 gallons or more is recommended for keeping various shrimp species.

Rasboras can make good tank mates for Penguin Tetras

Penguin Tetra Diet, Do They Need Algae In Their Diet?

In the wild they feed on algae so it makes sense to replicate this diet for them in their tank environment as well. You should supplement their food with some high quality flakes and frozen foods such as brine shrimp. They will, of course, also enjoy live or frozen foods such as bloodworms and mosquito larvae but these should only be offered on occasion as a treat and not routinely because this can lead to overfeeding which can cause disease problems in your fish.

Ideally, you should have aquarium plants so that the tank is covered in natural algae growth. The addition of floating plants to the tank also helps maintain bio-filtration and gives your fish somewhere to rest and hide.

Are Penguin Tetras Aggressive? - Conclusion

Penguin tetras can be a great choice for beginner aquarists who want to create an easy-to-maintain freshwater fish tank. They are not too demanding when it comes to care and maintenance, they don’t grow too large (about 3 inches), and enjoy swimming space but aren’t overly fussy about what they swim in. 

The best tank mates for penguin tetras are other calm species such as glowlight tetras, dwarf corydoras, rasboras, neon tetra and the serpae tetra. Penguin tetras are normally a peaceful fish species, perfectly suited to life in a community tank. Being a schooling fish, penguin tetras need to be kept in sufficient numbers to feel and safe, not doing so can often lead to problems such as fin nipping.

Providing you keep them in a large enough school, give them enough space, food, the right water conditions and suitable tank mates there is no reason at all to fear that your penguin tetras will be aggressive!