Are Neon Tetras Aggressive?

While rare, Neon Tetras can exhibit aggressive behavior under certain conditions. However, they’re known for being one of the calmest and most peaceful fish species.

Neon Tetras are a popular freshwater aquarium species that have brilliant red and blue stripes. They’re known for their hardiness once they get accustomed to their environment.

What makes them well-liked, though, is their social and friendly temperament. Neon Tetras naturally get along with one another and with other tank mates.

That said, there have been reports of Tetras becoming aggressive toward one another or their tank mates. This begs the question: are Neon Tetras aggressive?

In this article, we’ll dive deep into the reasons why some Neon Tetras may display aggressive behavior. Let’s jump in!

Are Neon Tetras Aggressive?

The short answer is no. Neon Tetras aren’t aggressive at all. In fact, aggression in Neon Tetras is so uncommon that it’s considered abnormal behavior.

Neon Tetras are schooling fish, meaning they prefer to be in groups with other Neon Tetras. They show their best colors and are at their healthiest when in the presence of others.

This social and peaceful temperament is also why Neon Tetras are the best choice if you’re looking for a fish species that gets along well with others.

Even so, certain circumstances and environmental factors can cause this peaceful fish to become aggressive.

Neon Tetra

What Causes Aggression in Neon Tetras?

Because Neon Tetras aren’t known for being aggressive, it’s often a cause for concern when they exhibit such behavior.

That’s why it’s essential to figure out what’s causing your Neon Tetras’ aggressive behavior. This way, you can try to remedy the situation and prevent it from happening again in the future.

Mating Season

Mating season is one of the primary causes of aggressive behavior in Neon Tetras.

Right before mating season, you may notice your male Tetras swimming in a square pattern. Then, during the mating season, these fish can be quite rambunctious.

Male Neon Tetras tend to “fight” over female Tetras, which is more commonly known as a courtship dance.

Neon Tetras can also become aggressive during the mating season if they’re kept in a community aquarium. Neon Tetra males may go out of their way to defend their territory.

What’s more, once the female Neon Tetras lay the eggs, they may become aggressive to protect their eggs from being eaten by other species.

Lack of Space

Although Neon Tetras prefer to swim in groups, they can become agitated if they don’t have enough room to swim around.

For example, if you keep more than six Neon Tetras in a 10-gallon tank, your Neon Tetras may not have enough space to swim in schools.

As a result, when irritated, these normally peaceful fish may become aggressive and start to fight with each other.


Food is another factor that can cause Neon Tetras to become aggressive. If Neon Tetras don’t get plenty of food or have easy access to food, they may start fighting with each other.

Fish generally tend to school less when food is scarce. What’s more, if Neon Tetras share an aquarium with other fish, they may have to compete for food.

As a result, if there’s competition for food, Neon Tetras are very likely to become aggressive.

Schools of Neon Tetras

Aggressive Tank Mates

When paired with incompatible tank mates, neon tetras can become aggressive. Larger, more aggressive fish species can attack, bully, and even eat your Neon Tetras.

In retaliation, your Tetras may start behaving aggressively to protect themselves against those who attack them.

Here are the worst Neon Tetras tank mates:

  • Angelfish
  • Golden Wonder Killifish
  • Red-tailed Black Sharks
  • Ruby Sharks
  • Other larger Tetra species, such as the Black Widow Tetra

How to Stop Neon Tetras From Being Aggressive

Because Neon Tetras aren’t naturally aggressive, figuring out and resolving the source of their stress is the quickest way to help them return to their peaceful temperament.

Provide More Space

If the cause of aggression in your Neon Tetras is lack of space, you can:

  • Upgrade to a larger tank
  • Split your fish between two tanks

Ideally, you want a tank that can hold one gallon of water for every inch of fish. Just make sure that your tank can accommodate at least six Neon Tetras so that they can group together.

You should also provide plenty of hiding space for your Tetras. These fish need hiding places to escape other tank mates or rest for a little bit. You can do so by adding plants, tunnels, and large rocks.

Monitor Their Feeding Behavior

If you suspect that the cause of aggression is over food, you should keep an eye on your Neon Tetras while feeding. That way, you’ll be able to determine if one species is hogging all of the food.

If that’s the case, you should move the Neon Tetras to an aquarium with fish of similar eating habits.

You may also notice stronger Tetras feeding more than weaker ones. In that case, you should separate the weaker fish from the others so they can feed properly.

Limit Stress

Limiting stress is the most effective way to avoid aggressive behavior in Neon Tetras. To do so, you need to provide them with the best possible environment:

  • Always clean the aquarium
  • Keep water temperature between 72 and 78 degrees Fahrenheit
  • Pair with compatible tank mates
  • Treat any illnesses, wounds, or infections as soon as possible
  • Move your Neon Tetras to a separate tank during the mating if they have tank mates

In Conclusion

The social, friendly, and peaceful disposition of Neon Tetras makes them popular aquarium fish. They prefer to live in groups of at least six Tetras and aren’t aggressive by nature.

However, Neon Tetras can become aggressive. A variety of factors, including a lack of space and food, can cause this behavior. Neon Tetras can also become aggressive during the mating season and from aggressive tank mates.

Most Neon Tetras become aggressive as a result of those stressful circumstances. As a result, it’s best to address the source of the aggression as soon as possible.