Are Neon Tetras Aggressive? 5 Reasons For This Behavior

Neon tetras are a popular aquarium fish known for their bright colors and active behavior. However, some aquarium owners have reported that their neon tetras have become aggressive, attacking other fish and even biting humans. There are a few possible reasons for this aggressive behavior in neon tetras. Let’s scroll down and discover now!

Are Neon Tetras Aggressive? (Causes & Treatments)

Neon Tetras are not recognized for being very aggressive fish, contributing to their widespread prevalence in aquariums worldwide. In point of fact, they have a propensity to be quite docile and straightforward to care for, which makes it simple to match them up with other fish that are a good fit for their environment. Neon Tetras are capable of displaying violent behavior under certain circumstances; although it is uncommon, it does occur.

Even while neon tetras typically get along perfectly well with one another the vast majority of the time, there may be conflicts when the fish are mating or feeding. Therefore, it is recommended that they be housed in groups of at least six. Although it is not renowned as an aggressive fish, it is nonetheless capable of showing hostile behavior.

Neon tetras behavior
Neon tetras behavior

What Causes Aggression In Neon Tetras And Their Measures?

Neon Tetras aren’t known for aggressive behavior and are much more likely to act accordingly in the aquarium. However, if you are experiencing fights between the two, you need to figure out why the battles are occurring to prevent them.

When these fish fight, it will cause a lot of concern since it goes against their nature, and perhaps there is something you can do to optimize their living conditions and prevent this from happening again.

Playing with neon tetras is their favorite activity. This will be done by chasing each other around the tank and jumping into it high. The difference between fighting and playing behavior will usually be easy to see.

+Resource Guarding

Fighting may break out when your aquarium fish are being fed or when the Neon Tetras are near something edible in the tank. When this happens, you may be dealing with resource guarding. In most cases, resource guarding is related to something else and is not a unique problem.

Some fish can get aggressive when another species approaches their food, but Neon Tetras tend to be friendly for the most part. Fish may feel a need to guard their food supply because of lack of space, which we’re going to talk about in a minute.

Solution: If your Neon Tetras are fighting, it may be helpful to move their food away from the center of the tank. Additionally, try to create more hiding spots for them.

+Lack of Space

Neon Tetras become angry and agitated when there isn’t enough area for them to swim around in. Irritated fish are more inclined to lash out and start (or end) fights with other fish, so keep this in mind if you see conflicts in your tank.

Examine your fish tank to determine if your pets have enough area to swim, play, eat, and generally flourish. If the tank is too small, try purchasing a new tank or removing some plants and/or tank habitats. A full tank is attractive, but Neon Tetras require their place.

Solution: It is advised that the tank have two gallons of water for each fish in the tank to handle a school of Neon Tetra appropriately. The tank should be able to store twenty gallons of water if your school has 10 Neon Tetras.

You should provide your fish with different hiding spots in addition to a greater room. You may do this by adorning the tank with decorations, buildings, and natural plants. Weaker fish will be able to locate a space to escape a hostile environment rapidly.


Male and female neon tetra
Male and female neon tetra

Although aggression among Neon Tetras is considered an abnormal characteristic, it can happen during mating. Their eggs are likely to be eaten by other species, so breeding them in a community tank is not recommended for this reason.

Solution: You should place your pets in a separate tank for mating to avoid aggression at any time. As much as possible, keep your Neon Tetras separated from the main tank to avoid putting them in a position where the attack is required to protect themselves and their spawn.

You shouldn’t put their water in conditions that might encourage them to breed. The Neon Tetra won’t likely mate if the conditions are less than ideal. You can keep your fish separate or keep the two sexes together to be absolutely sure they won’t breed.

+Water Conditions

If you are sure that the tank size is correct, that your Neon Tetras have enough area to swim, and that everything appears to be in order, it is time to start thinking about the water conditions. Although it is not the most prevalent cause of the fighting, poor water conditions can make the Neon Tetra uncomfortable, quickly developing into irritation.

Solution: On the good side, Neon Tetras aren’t fussy about temperature, water hardness, or other factors, but it’s still something to keep an eye on. Neon Tetras like water temperatures ranging from 70°F to 81°F. They prefer dark illumination, soft water, a pH between 6.0 and 7.0, and a tank with a capacity of at least 10 gallons.

+Small Group

Schooling is a typical feature of neon tetra
Schooling is a typical feature of neon tetra

Neon tetras school together. As they grow in numbers that are too small to function adequately as a school, they may become irritable and aggressive. To thrive, they need to be held in tanks with at least six specimens.

Individuals who do not meet such requirements will not feel secure and comfortable around an aquarium. As a result, they can become easily triggered and attack other fish if they feel threatened.

Moreover, fish that are forced to live in small numbers can suffer weakened immune systems and severe stress. They may become depressed as a consequence.

Solution: Introduce more neon tetras into your tank. They will not only become friends but will also help to form a school. As long as the tank has at least six specimens, they will be happy and content.


Food is another major cause of hostility in Neon Tetras. Because they are school fish, there is a lot of rivalry for food. If there are other fish in the tank with the school, their hostility will rise.

Solution: As a result, you should begin watching them eat. This will determine whether you need to feed your fish more or segregate smaller and larger fish. Providing a few flakes of food to each fish is advised.

Even if you feed your fish plenty, that doesn’t guarantee that every fish has easy access to the food. After observing them dine a few times, you’ll identify which fish are fighting and becoming aggressive over food. These fish may be separated, and the fighting should end.


Plants in the fish aquarium
Plants in the fish aquarium

You’re highly likely to see aggression in your Neon Tetra when it’s stressed. Fish can become stressed for many reasons. One is that they may not be happy with their water environment. They live in tropical waters, so temperature plays a significant role.

In small aquariums and crowded tanks, neon tetra can get stressed. If the tank doesn’t contain enough decorations which they can hide, they can become stressed as well. The way your fish behaves will tell you if they are stressed.

You might also notice additional signs of stress in your Neon Tetra, such as aggression. Loss of appetite, changes in swimming style, hiding more often, and sudden, jerking movements might be signs of illness. Additionally, they may stay near the water’s surface, change their appearance, and lose color.

Solution: Ensuring their water temperature is just right is one of the most excellent strategies to reduce stress-related aggressiveness. To be happy, they require the water to be between 72 and 78 degrees Fahrenheit.

To decrease stress, you’ll also need to clean the fish tank. You may achieve this by cleaning roughly 25% of the water through cycling. To avoid adding to the fish’s stress, gently replace the water in their tank.

+Illness or injury

If your Neon Tetra is ill or injured, they may exhibit aggressive behavior. Even minor injuries or illnesses can cause your Neon Tetras to be in pain and discomfort. A Neon Tetra can contract a variety of ailments, including ich, growths on their lips, and Neon Tetras sickness.

Solution: You should first place them in a quarantine tank to address this issue. If you cannot determine the cause of their illness, you should consult a veterinarian as soon as possible. If you know why they are sick, treat them with the appropriate medication. They can be reintroduced to the main tank after they are no longer unwell.

How To Tell Neon Tetra Are Aggressive Or Playing?

Neon tetras are playing
Neon tetras are playing


The neon tetra is a fascinating and fun organism to watch. Do not get alarmed when you see these creatures chasing each other. There might be nothing to worry about.

You’ll also see them jump high outside the tank when they are excited. Make sure you provide them with a large tank so they can swim as they wish.

Aggressive Signs

It is common for Neon Tetras to swim back and forth, chasing one another, and behave somewhat wildly, as they are incredibly playful fish. This is not a cause for alarm, although it may take some time for the inexperienced eye to distinguish between regular play and Neon Tetras fighting. Here are several indicators of aggression:


Consider the swimming pattern of your neon tetras. One might be bullied by the others if it appears to be swimming separately. This type of fish rarely fights, but they are known to bully each other when a new one is introduced.

The neon tetra will stop swimming together with the rest of it is severely bullied. In addition, you may notice the colors of the bullied fish changing over time. Your intervention is needed in this situation, as otherwise, the fish might die.

+Fin Nipping

Another potential problem is the tendency of Neon Tetras to nip the fins of other fish, both other Neon Tetras and other species. The risk of being nipped is greater for fish with longer fins. It is a sign of aggression when your Neon Tetras are nibbling at other fish’s fins. Stress usually causes this behavior.

Video: Are Neon Tetras Aggressive?


Does solitary tetra get aggressive?

Neon Tetras are adapted for living in schools. Tetra gets stressed when kept alone in a tank and starts showing aggressive behavior. You can add five or six more tetras and see how they get along over time.

When do tetras fight injury? or die?

A smaller fish usually gets injured when fighting with a larger one. Because of its nipped fin, it cannot swim. Therefore it can die.

Also, the tetra that is consistently attacked and bullied gets stressed, and it just takes a matter of time before it dies.

Can neon tetras kill one another?

Neon tetras can kill one another, but they might not do it in the way you imagined. These fish are not vicious attackers nor agile sparring partners, but they are clearly capable of severely injuring their opponents.


5/5 - (1 vote)