Why Are My Neon Tetras Fighting?

neon tetras in a fish tank

Neon tetras are one of the more popular fish species for beginners of aquascaping. They’re easy to breed, compatible with other fishes, and relatively small. However, they can be quite aggressive towards each other. Even if you have a large aquarium, they can cause injuries to each other near the surface or at the bottom of your tank due to their fighting behaviors. So here’s a handy tip sheet outlining the main causes of a fight among neon tetras.

1- Overcrowding

neon tetras overcrowding

The key to keeping your fish happy is to provide them with enough room, and this is particularly important for tetras. In the wild, neon tetras live in large schools of up to 100 fish. In captivity, however, they can become stressed if there are too many of them in one tank.

Neon tetras are very active swimmers and need plenty of space to swim around to stay healthy. They also need room to hide from predators or other aggressive fish if they feel threatened by them.

When you have overcrowded tanks, it can cause stress among your fish which leads to aggression and even death. If you notice that your tank is becoming overcrowded and notice that the water quality is starting to deteriorate, then it’s time to do some research on how you can reduce the number of fish in your tank or upgrade your aquarium into a bigger tank so that there’s enough room for everyone!

2- Chemical Imbalance

Neon tetras are sensitive to the nitrate and ammonia levels in their tank. A sudden increase in these levels can cause aggression.

Neon tetras are also very sensitive to water quality. They need clean, well-oxygenated water that is between 25°C / 77°F and 30°C / 86°F. If you keep your water at the wrong temperature, your fish may become stressed and aggressive.

If you notice your fish becoming more aggressive than normal, check your water quality immediately. If you have a filter on your tank, clean it regularly to ensure that it’s working properly and isn’t clogged with dead algae or waste products from your fish.

If you don’t have a filter, consider getting one as soon as possible. It will keep your water cleaner for longer and improve its oxygenation, which will make it more pleasant for all of your fish.

3- Stressful Environment

Neon tetras are extremely sensitive to poor water quality, so it’s important to maintain good water conditions. They do best in soft, acidic water with low levels of dissolved minerals and other substances. If your tank has a lot of algae or other debris, you may need to clean the filter more often than usual.

Neon tetras can also be stressed by sudden changes in temperature or pH levels. If you’re planning on adding new fish to your aquarium and notice that the neon tetras are acting differently than usual, it may be because they’re being stressed by the new arrivals.

If you notice that your neon tetras have been fighting for some time now, try doing some research online about their natural habitat and see if anything looks familiar in your tank setup or behavior patterns. This will help you determine what might be causing the stress and how to fix it quickly.

4- Competition For Food

neon tetras fighting over food

Competition for food is one of the most common reasons that fish fight. If you have too many fish in your tank and not enough food, this can cause some stress and aggression between the fish.

Neon Tetras are often found in groups in nature where they will compete for food resources with other species of fish. In your aquarium, you can minimize this competition by making sure that there is enough food available for all the fish to eat their fill at each feeding. If you have multiple neon tetras in your tank, try feeding them separately so that each group of neon tetras gets its own mealtime when there is plenty of food available for everyone to eat at once.

If you have more than one tank, try feeding them separately so that they don’t compete for food. You can also try feeding them different foods so that they don’t compete with each other over the same food.

5- Addition Of A New Neon Tetra

neon tetra in a fish tank

When you add a new fish to an established tank, there is a chance that some of the other fish will not be happy with the new addition. Neon tetras are very peaceful and non-aggressive species, so if they are fighting it is a sign that something is wrong.

It is also a common reason for fighting among neon tetras when you add new fish into an established tank. The new fish may be too aggressive or simply not compatible with the other fish in the tank. Unfortunately, there isn’t much you can do about this situation unless you want to separate all of your neon tetras into another tank (which could cause stress for them).

You can also try adding some floating plants or hiding places for your tetras. This will help reduce their stress and make them less likely to fight.

6- Overfeeding

Overfeeding can also cause fighting among neon tetras. When neon tetras are fed too much, they can become aggressive towards each other. This is because overfeeding stresses them out and makes it hard for them to digest food.

They should only be fed once or twice per day with small amounts of high-quality foods such as flake food and frozen brine shrimp nuggets or bloodworms. You can try adding only a small amount of food at first and then gradually increasing the amount over time. This will allow your fish to get used to eating more food at once, which is easier on their digestive systems.

7- Bullying

Neon tetras are very sensitive fish and they can be bullied by other types of fish. They are usually bullied by larger, aggressive fish and may also be harassed by other neon tetras. One reason why neon tetras fight is because they are too small to defend themselves against larger fish. Another reason why neon tetras fight is that they have different personalities; some are aggressive while others are shy.

Neon tetra bullying can lead to stress and even death in your aquarium if not corrected quickly. If you notice that your neon tetras are fighting frequently, it is important that you take steps to stop the bullying behavior as soon as possible.

If you notice that your neon tetras are being bullied by another type of fish, try adding another type of tank mate that will help protect them from this type of aggression and bullying from other fish.

8- Fighting Over Female

why are my neon tetras fighting

If you have a group of male neon tetras, they may fight over a female that enters the tank. This is because females release pheromones into the water which can attract males from other tanks. There are several ways to prevent this from happening:

The best way to prevent this is to keep your neon tetras in a species tank or at least a tank that is divided into sections so that no other fish can get in. If you have fewer than five males, it’s not too hard to keep them separated from each other by using dividers or by splitting up your tank into sections. If you have more than five males, it might be difficult or impossible to keep them apart without separating them permanently into different tanks.

If you don’t want to separate your fish due to space limitations or other reasons, another option is placing a divider between your groups of neon tetras (ideally one per group). You could also try adding an extra filter on the opposite side of your tank and adding more plants or decorations there so that there is enough cover for each group of males without having them all together.

9- Fighting For Dominance

If you have more than one male neon tetras in your aquarium, they may be fighting for dominance. Almost every species’ males are aggressive towards each other and will fight to establish dominance.

Male neon tetras always try to become the dominant fish in the school. This can happen even if you have only one male and female in the tank, but especially if you have a large number of neon tetras.

10- Fighting For Territory

Neon tetras get along well with other fish, but they can be territorial, particularly if they’re kept in a small tank. If there are no other fish in the tank, they’ll probably get along just fine. If you do add other fish to your tank, however, the neon tetra will often become aggressive toward them. The best way to prevent this is to make sure your aquarium is large enough so that each fish has its own territory and doesn’t feel crowded.


Neon tetras are beautiful fish, but they are also known for aggression. Fish will fight with anyone and for a number of reasons. However, it is possible to reduce this behavior by setting up the tank appropriately and providing natural cover. The key is to create an environment where each fish can feel like they have their own territory in the tank, and there’s not much competition for food (since that can incite some aggressive behavior as well).

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