You have carefully decorated your new aquarium, placed it into the most visible part of your home, and brought some amazing neon tetras inside. After some initial days of fun observation, you noticed one of your tiny pets has died.

And the next day, another has passed away. But what brought to multiple fish dying out? If you are being super-worried, which is completely understandable, and are now asking yourself “why do my neon tetras keep dying?”, there can be several answers to that.

Reasons Why Neon Tetras are Dying

Knowing which factors need to be checked right away in order to distinguish one cause from another is essential and will often present the difference between saving your pets or having to face their collective death.

– Poor Water Quality

Poor water quality is probably among the top reasons which bring to these little fish dying out. Indeed, they are extremely sensitive to the conditions of the water in which they live. A good filtration system is, therefore, vitally important.

Make sure to collect all visible debris regularly and to perform partial water changes, even if you have a high-quality filter. Any change in the water parameters can lead to serious health complications to your delicate pets, so it is needed to keep water impeccably clean.

As an addition, you can plant some aquatic greenery across your tank, as this will not only keep your fish happy, but it will also improve the water quality.

You should never rely on your personal estimation of the water conditions. Instead, make sure to perform regular water tests to get accurate data. The pH levels should be anywhere between 6 and 7 for permanent tanks, and somehow more acidic for breeding tanks.

Neon tetras need soft water to thrive, and it has to be really clean. As for any other fish, ammonia and all other dangerous particles need to be at 0.

– Non-Cycled Tank

If you have forgotten to cycle your tank before placing your neon tetras inside, they will almost certainly collectively die very soon.  This can cause massive shock states to your fragile pets, so placing them into an established and mature tank is particularly important.

A non-cycled tank does not have any healthy bacteria yet, meaning there is no natural way of the fish waste and food residues being broken down. This can cause ammonia level spikes, making your fish suffer severely or die.

Before placing your neon tetras inside their permanent tank, this should be fully cycled.

Some fish species can handle well their tanks being cycled with them inside, but this is not the case with neon tetras, which are super-sensitive. A full cycle process can take about 4 weeks to occur, so please plan ahead.

– Chlorine

Chlorine is a perfectly safe addition to our tap and swimming pool water. It kills all the dangerous bacteria and allows people to use such water safely. But the emphasis is right there: safe for people, not for fish.

Therefore, any time you pour some tap water inside your fish tank (either for a partial or a full water change), you must condition it first. Otherwise, all of your neon tetras will die. Indeed, chlorine is highly toxic to these little creatures.

Please make sure to treat your tap water with a water conditioner before pouring it into your established tank. There are several affordable yet highly efficient conditioning products available online, and they are all so simple to use.

– Ammonia

Sadly, ammonia is one of the most dangerous enemies for any fish. And with neon tetras being overly sensitive to such particles, the danger increases even more. Therefore, this has to be at 0 at all times.

Ammonia levels usually spike when there is any kind of waste along with the aquarium. For instance, fish waste or food leftovers which sink to the bottom and stay there for a while can increase such levels.

Always make sure to remove all visible debris or waste from your neon tetra tank, perform partial water changes regularly and constantly monitor all water parameters.

Whenever these go out of the normal values, you will have to intervene as soon as possible to get them back onto a healthy level.

– Overfeeding

Overfeeding is a more serious problem than we like to imagine it is. Indeed, it is not uncommon for many neon tetras dying because too much food has been offered to them. This problem is actually two-sided.

The first issue is related to your pets actually ingesting all the extra food you offer them, and they start developing health concerns such as constipation soon.

On the other side, if your fish rejects the extra food and lets it sink to the bottom, this will soon cause increased ammonia levels across the tank, making the water toxic.

Overfeeding is so easy to avoid by simply offering your tiny fish enough small portions.

You can feed them 2 or 3 times per day, as you prefer, but it is necessary to only offer such meal sizes which they can eat up in 3 minutes. All the rest is excessive food, and it should be scooped out of the tank if it starts sinking.

– Overcrowded Tank

An overcrowded tank involves several concerns, and they are all life-threatening to neon tetras. Being schooling fish, they swim simultaneously, as a group. Therefore, if there are too many fish in there, they can bump into each other.

This can, consequentially, trigger aggressive behavior in these usually peaceful pets, and they can start fighting each other. Alternatively, even if an overcrowded tank does not bring to hostility and stress, it can simply worsen the water quality.

Indeed, too many fish can increase ammonia levels and reduce oxygenation, seriously compromising your pet’s wellbeing.

An overcrowded tank is simple to avoid by an effective calculation of the water/fish ratio. An excellent thumb rule for neon tetras is allowing one gallon of water per every inch of fish. For instance, if you own up to 10 neon tetras, they can happily function into a 10-gallon aquarium.

– Water Temperature

Neon tetras are tropical fish that require warm water conditions to thrive. Ideally, the temperature levels should be anywhere between 72- and 80-degrees Fahrenheit. And, more importantly, the levels have to be stable at all times.

Any oscillations in the temperature can lead to a state of shock, distress, or can eventually bring to various diseases. A drastic change in water warmth can immediately cause your colorful fish to die.

Temperature issues can be controlled easily with the help of a simple thermometer. Place it at the middle of your tank and observe the values daily.

Additionally, always place your tank with neon tetras away from windows or other sunny areas of your home, as sun rays can also lead to temperature shocks.

– Diseases or Parasites

If you have ruled out all of the previously mentioned causes of death, there can alternatively be a contagious disease or a parasite that is making your beloved pets die. And the most common by far is surely the neon tetra disease.

This is caused by a parasite that can be found in the tank water and can quickly spread among your neon tetra school. Indeed, this deadly disease can literally eat your little pets from inside out and can cause the entire tank to become infected.

Early symptoms include restlessness and isolation from other tank mates. If these persist, your pets may soon start having visible lumps across their bodies and lose their vivid coloration.

If you spot such changes, you should isolate your affected fish immediately. Sadly, there is no known cure for such disease until now, so prevention is your best option to save your little pets.

Keeping Neon Tetras Healthy & Happy

Providing a healthy and happy life to your favorite aquatic pets is not a complicated task at all. All you need to do is follow some simple guidelines and keep a close eye on any behavioral changes.

  • Always purchase your neon tetras from a trusted source and quarantine your new fish for 2 weeks before placing them into their permanent tank.
  • Always perform a full tank cycle before introducing any of your neon tetras to it.
  • Never keep a school of less than 6 neon tetras and ensure they have enough living space.
  • Provide your pets with ideal water requirements and regularly perform partial water changes.
  • Feed your pets with a healthy and balanced diet, consisting mainly of apposite commercial flakes.
  • Monitor your pet’s behavior and do not disregard any behavioral changes.

Wrapping Up

It is not uncommon for these amazing delicate fish to die off when introduced to a new environment, although it is always sad. However, with just a bit of research and planning, these unwanted situations can be easily avoided.

Please ensure to follow some simple guidance before even deciding to adopt these wonderful pets, and we are sure you will be able of providing them a healthy yet happy home.

Written by Fabian

Hey, I'm Fabian, chief editor at Aquarium Nexus. I really enjoy the aquarium hobby and love sharing my experience with others. If you have any questions feel free to contact me or leave a comment below.

Leave a Comment

Your email address will not be published. Required fields are marked *