Neon Tetra Behavior: Are They Aggressive/Fighting or Playing?

neon vs cardinal tetra

At present, everywhere people want to interest their life with something positive and peaceful. You think, wouldn’t it be awesome having a shining jewel of the aquarium, a Neon Tetra?

A beautiful fish with the shimmering iridescent silver-white abdomen, and light-blue back along with bright red stripe, extending towards the tail. This combination of color is what makes Neon Tetra famous among all other fishes.

Moreover, Neon Tetra was imported from South America originally and is thriving among many countries due to its popularity.

Some popular Neon Tetras are True Neon Tetra, Diamond Head Neon Tetra, Longfin Neon Tetra, Red Neon Tetra, Albino Neon Tetra, Green Neon Tetra, Gold Neon Tetra, and Black Neon Tetra.

How Neon Tetra Behave?

Neon Tetra is a sensitive, peaceful, and non-aggressive fish, swimming gracefully around the tank, most commonly in a group. It is a little fragile, but being an aquarist, it’s a good chance to learn some new skills, isn’t it?

Being A Peaceful Creature By Nature, Why Neon Tetra Acts Aggressively Sometimes?

Neon Tetras show aggression under certain circumstances, such as while feeding or while mating. Having a small size tank, but many more tetras than recommended will trigger their aggressive behavior.

Now, is your tank of appropriate size? If you want to know the detail on tank size and several fishes you can keep, kindly go through this link:

Or, for basic information, keep reading this article.

Likewise, protecting their territory is in their nature. They also act aggressively while doing so.

But, they can also be in a serious kind of danger. You should feed them properly, check whether they have caught a disease or not, find out the level of ammonia, and also check the water parameter. You must monitor all these requirements or, else your fish can die.

Do You Know, An Aggressive Tetra Can Make Others Aggressive Too?

Aggressive tetra if goes on attacking other tetras, the attacked ones can get stressed and charge it back. Also, they can lose their temper and kill.

Learn more about tetras’ aggressive nature here.

What About Solitary Tetra, Do They Get Aggressive?

Neon Tetra is adapted to live in schools. When you keep Tetra alone in a tank, it gets stressed and starts showing aggression. Just bring 5/6 more tetras and see how they get along with each other with time.

Why Are Your Neon Tetras Fighting?

Are your Tetras ‘really’ fighting? Or, are they just mating or chasing, or fin nipping?

Fin Nipping

Usually, we misunderstand fin nipping behavior by fighting. Neon Tetras go around nipping other’s fins if stressed. Also, whichever fish has long fins, usually its fin gets nipped by other fish.

Further, when a new fish is introduced, older ones go around chasing and fin nipping. It’s just they are unknown and are protecting their territory. Tetras also fin nip to protect themselves from some kind of danger or threat.

This is completely normal, you don’t have to dwell on.


Even mating seems like fighting, but it is a very natural manner. Male tetras fight over female tetra, you don’t have to have deep thought on that.

If you want to know the difference, just separate one male and one female tetra in a suitable tank condition.  Remember, you do not change the environment inside the tank.

Furthermore, when you see male tetras swimming in a square pattern, note it, mating will start soon.


Neon Tetras are very exciting and playful organisms. When you see these creatures chasing one another, don’t panic. They might be just playing.

You’ll see them getting excited and jumping high in the tank as well. So, give them a large tank to swim freely however they want.

Swimming Style

Neon Tetras have their unique way of swimming. As mentioned before, they like swimming in schools. But, keeping 7-8 tetras in a small tank is not the solution.

Anyone can get irritated when there are more creatures than required. And, the same goes for tetras. Although they like swimming in schools, they want their space. Moreover, for 6 fish, have a tank of size 10- gallons.

However, Tetras are not kind of creatures who fight, but if they are truly fighting, then there, you need to show concern. They fight if there isn’t enough space to swim. Focus on tank size. Also, make sure you don’t keep fish that are not compatible with Tetras. This triggers aggressive behavior among your fish.

Additionally, check whether the water level and the temperature are maintained as per their need. The change in their habitat affects their behavior, and they become aggressive.  They express their aggression as fighting.

Desperate To Know If Neon Tetras Bully One Another?

You’ll get your answer right here.

Neon Tetras enjoy swimming in school. Tetras are comfortable with one another in the tank. But, as mentioned earlier, as you introduce a new Tetra, the older Tetras can bully the new one. However, as time passes, they get along and adjust just fine.

Also, aforementioned, if you have opposite gender Tetras then, male Tetras fight over female Tetras. In such a case, they bully and attack one another. The best solution is to separate male and female Tetras.

You need to know, extremely bullied Tetra doesn’t swim with the school, and its color starts fading in due course.  If you didn’t take care of, this leads to its death.

Are Your Fish Not Compatible With Neon Tetras?

You might want friends for your Neon Tetras, and having a thought of Goldfish is very common, as they both have mesmerizing appearances. But, Goldfish and Tetras have different social habits.

Tetras like warmer environments, and for Goldfish, they want the opposite. Moreover, goldfish can also eat your Tetras.

Similarly, some aggressive fish like Cichlids, Barbs cannot exist together with your Tetras.

Nevertheless, Angelfish, Guppies, Loaches, Mollies, Plecostomus, are perfectly compatible tank mates of Neon Tetras. Of course! Tetras bully and fin nip these fish when they are new to the family, but later they become friends.

Read the article “Tetra Fish Tank Mates And Fish To Avoid” to get in-depth knowledge.

What Happens When Tetras Fight? Do They Get Injured? Or, Do They Die?


Whenever your fish are fighting, the smaller one usually gets injured. Its fin gets nipped and it can barely swim, hence it can die.

In the same way, the one tetra who has been attacked and bullied gets stressed, and it’s just a matter of time until it dies.

Why Do Your Neon Tetra Die So Easily?

Neon Tetras are very sensitive creatures. Little ups and downs in their surroundings lead to their death.

As mentioned above, one of the reasons your Tetras are dying is stress. Stress eventually kills your Tetras. Moreover, as prior mentioned, a proper set up of an aquarium is very important. If your aquarium is too small, and also you are increasing the number of fish then, such activity can lead to their death.

Equally important, whenever you are bringing friends for your Tetras, make sure they are compatible. They must get along, or else, one will attack another.

You are a very fish loving person, and you want to feed them as much as they need. On the contrary, you mustn’t overfeed them.

You might ask, how overfeeding kill my fish?

Here, is the answer. When your fish eats more, it’s natural that it poops more. And this makes the water inside the tank detrimental. Thus, your fish dies.

Are you with me?

Besides, your fish can have the disease, or it can be just old.

I recommend you to read the article “Are Tetra Fish Easy to Keep and Care for?” if your tetra are dying often.

Why Are Your Neon Tetras Disappearing?

When you count your Tetras and see one or two less, don’t panic, they are not dissolved in water or disappeared. Sometimes, your fish can feel uncomfortable, unsafe, sick, or irritated. Thus, their color fades and they become transparent.

Want To Keep Neon Tetras In Your Water Tank?

If yes, make sure you take proper care of these buddies. Here are some factors, you need to a major focus on:

Tank Size According To the Number of Tetras

Tetras like swimming in a group. If you are having up to six fishes then, a 10-gallon tank size would be good. But, if you are thinking of increasing the number then, have a tank of 20 gallons.

As Tetras are mid-water fish, a taller tank would be awesome for them to move around more comfortably.

Diet and Feeding

Tetras are very active and they need more energy to perform their activity. It is very important to feed them correctly, properly, and every day.

Further, Tetras have a very small mouth. Rather than flake food, it would be better to feed them with pellet food such as Sinking-Micro Pellet.

Also, you can treat them with Frozen Bloodworms or vegetable material. Do not forget to chop them into pieces, as mentioned above, they have a small mouth and can choke.

Learn more about the Neon Tetra diet and Feeding habit here.

Filtration for Neon Tetra

Do Neon Tetras need the filter, or they don’t?

Neon Tetras need filtration to introduce air into the water so that there is a place for beneficial bacteria to grow.

Or, if you are familiar with fish keeping, and know what you are doing, then you will acknowledge the relationship between the planted tank and underlined layer. In such a case, no filtration also works fine.

Moreover, even though Neon Tetras have no specific need for filtration, however, go for the GpH (Gallons per Hour) rating, and get four times your tank size.

Lighting and Heating

Neon Tetras are gradually developed in dark brown water. If you put bright lights, you’ll make it worse. And, if you are raising eggs and fry, no light at all. They are sensitive to light. They can get killed.

Additionally, if you want to decorate your tank with plants, a floating plant would be perfect. They provide shade to your Neon Tetras. Having green plants will give a natural look to your Tetras.

Furthermore, Tetras being a tropical fish, they survive in a warmer environment. Keep your tank at 72 degrees F – 76 degrees F. If they are breeding, make it 75 degrees F – 76 degrees F.

Tank Mates

As mentioned above, Cichlids, Barbs, and Goldfish are not compatible with your Tetras.

Fishes like Angelfish, Guppies, Loaches, Mollies, Plecostomus, Cardinal Tetras, Ghost Shrimp, and Halfbeaks perfectly go with Tetras.

You must know, incompatible tank mates can attack, bully, and also eat your Tetras.

Breeding Tetras

Usually, Neon Tetras breed when they are 12 weeks old. You can keep adults in a separate tank and leave the breeding ones alone. Neon Tetras are comfortable with Cardinal Tetras.

Besides, to establish a breeding environment, first have about a 24-inch long tank and fill it with rainwater. Then, keep the tank 75 degrees F – 76 degrees F warmer. Put some stuff like Java moss or spawning matt to avoid hungry parents from eating eggs.

Within a couple of weeks, you will be amazed seeing little Neon Tetras, coming out showing their shimmering color.

Check the article “Breeding Tetra Fish – Step By Step Guide” for step by step breeding guide of tetra.

Disease and Treatment

Neon Tetras catch infection very soon so, you must be prepared to diagnose and treat ill Tetras. They get affected by a disease caused by a protozoan organism, Pleistophora Hyphessobryconis. It is caused when Neon Tetras are fed with dead fish, or worms containing protozoan’s spores.

As symptoms, fish starts to hide, you’ll notice lack of coordination, lumps under the skin, and white patches all over the body.

Honestly, there is no particular treatment for Neon Tetra disease. You have to separate the infected fish from the tank to stop spreading to other fish. You must keep infected fish in a hospital tank, and can try treating with Kanamycin.

I know your heartbreaks, but if Kanamycin doesn’t work, then there is no other option.

Check the article on Tetra Fish Diseases and Treatments.

Final Words

To sum up, as prior mentioned, Neon Tetras are not aggressive by nature, but the circumstances around them trigger their aggressiveness. Whenever, you see them fighting, bullying one another, don’t get anxious, rather know the reason behind their behavior and act accordingly.

Friendly natured Neon Tetras serve your home with peace and positivity. I know they are a bit sensitive, but beautiful creatures to have as a pet.

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