Neon Tetra Disease, Signs, Symptoms, Prevention and Treatment

Estimated read time 9 min read

Important Note: does not intend to provide veterinary advice. We go to great lengths to help users better understand their aquatic friends. However, the content on this blog is not a substitute for veterinary guidance. If you suspect you have an infected fish, please contact your nearest Veterinary.

The Neon Tetra is a relatively tiny fish, which can reach a maximum size of 1.5 inches. But, some of them have been known to grow up to 2.5 inches as well.

The most striking trait of the Neon Tetra is their color. The greenish-blue iridescent hue, along with two horizontal blue stripes on either side, gives them a distinct appearance.

There are two red stripes from the middle of the body to the caudal fin. Along their back, they develop an olive green sheen. The fish is mostly translucent, apart from the markings they have on the bodies. You can almost see some of their internal organs.

Distributed primarily across Latin America, the largest concentration of this fish can be found in the wild in the Amazon River Basin.

While naturally, the fins and tail of the Neon Tetra are pretty small, there are hybrid versions of the fish that have longer tails, which are very common now.

Because of their beautiful appearance and ease of care, Neon Tetras are often sold as a beginner fish to those first entering the hobby.

Which leads to the question of why do neon tetras die so easily?

Well, for one, they are prone to catching something called Neon Tetra Disease, which is a prevalent disease that affects not only Neon Tetras but many other fish.

Below you will find out how to identify this disease, what you can do to prevent it, and if by some unlucky chance your Neon Tetra is infected how to treat your fish.

Want to learn more about the Neon Tetra? Check out our Neon Tetra Care Guide.


Equipment You Might Need For Your Neon Tetra

  1. Aqua Clear – Fish Tank Filter
  2. NICREW Classic LED Aquarium Light
  3. Fluval M Aquarium Heater
  4. Python Pro-Clean Gravel Washer and Siphon Kit
  5. Marina Algae Magnet Cleaner
  6. API Freshwater Master Test Kit

What Is Neon Tetra Disease?

Neon Tetra Disease is a degenerative condition that is caused by a parasite called Microsporidian and can affect many other fish species, not just the Neon Tetra.

A degenerative disease is defined as:

“The continuous…degenerative cell changes, affecting tissues or organs, which will increasingly deteriorate over time”. – Wikipedia

Signs Your Fish Might Be Sick

If you monitor your fish closely every day and notice strange behavior and start to ask questions like;

  • Is my Neon Tetra sick?
  • Why is my Tetra losing its color?

There is a good chance something might be wrong. If that’s the case and you suspect your Neon Tetra is sick, you should look for the following signs of Neon Tetra Disease (NTD)

Symptoms Of Neon Tetra Disease

While many other forms of sickness can make your neon Tetra Fish sick, we are focussing on NTD, where some of the first signs can be loss of color and no longer schooling with their tank mates.

Additional signs that NTD might be the cause are things like growths, cysts or even spinal deformities, causing the infected fish to appear misshaped.

Here are a few of the first signs & symptoms of Neon Tetra Disease that you can look out for.

  1. Restlessness
  2. No longer schools with the others
  3. Loss of color, pale
  4. Cysts or growths
  5. Slow movement, difficulty swimming
  6. Spinal deformities, curved
  7. Prone to other infections like; fin rot, swim bladder

NTD can be differentiated from other infections by its failure to respond to antibiotics and other treatments. So if you are trying to quarantine and medicate and things don’t improve, chances are its NTD.

Identifying Real Or False Infection

When trying to identify NTD, you need to be sure that you’re not just dealing with another common sickness because many other fish sicknesses can have very similar symptoms.

For example:

One of the main things to look for with NTD is white spots or even cysts. Which could look a lot like Ich if you don’t have a lot of experience identifying other types of sickness.

In most cases, if you feel your fish is sick immediately, remove them from the tank for treatment as you usually would.

As I mentioned above, there is no treatment for NTD, if your fish responds well to quarantine and medication chances are you didn’t have NTD.

Here’s a good video from MyHecticLifePets about five common fish diseases and how to spot them.

What Causes Neon Tetra Disease

NTD is caused by fish eating other fish, yes this happens a lot, especially in large hatcheries where injured or sick fish are slowly left to die and appear to the other fish as live food.

The dead/dying fish may have been infected or have a parasite called Pleistophora hyphessobryconis, which primarily eats the fish from the inside out.

These parasites will grow in the intestines and start to eat/burrow the intestinal wall, then proceed into the muscles and skeleton of the fish. This causes cysts to form damaging the muscles, skeleton, and tissue, ultimately leading to dead fish.


Okay, so how do you prevent Neon Tetra disease?

Well, like with most problems in a fish tank, it starts with the maintenance of your aquarium water. Regular water changes, as well as cleaning of the filter media, decor and gravel, will help prevent not all infections and disease.

Another thing to ensure is that if you ever see a dead fish or even a sick fish, you should remove it immediately to ensure the possible transmission of NTD is not possible.

Lastly, when purchasing new fish, try to ensure the store tank doesn’t have any dead fish floating around that have possibly been eaten by the other fish in the aquarium.

Cures & Treatments

Unfortunately, as we’ve already mentioned, no treatment will be effective once your fish has NTD. Some medications have been shown to provide temporary relief, but this is because the medication prevents any further infections or other problems like

Another problem with NTD is that once it’s in your tank it will likely always be present in the tank, and some of the unaffected fish might just be carriers. So to truly get rid of it, you might need to strip down the entire tank, sterilize everything and cull your stock.

The good news about all of this is NTD isn’t all that common nowadays. In most cases, your fish likely has another treatable sickness.

How Long Does Neon Tetra Disease Take To Kill

In most cases, it can take a week or two or up to a month or longer. This really depends on a lot of things but it really depends on when your fish was infected and how fast the parasite is growing inside your fish.

If you just purchased your fish you actually have no idea how long they may have been infected.

In either case, if you suspect your fish is infected it’s best to remove them, quarantine them and try some treatment to medicate and hope for the best.

Images & Pictures Of Neon Tetra Disease

I’ve done my best to find a few pictures to show you what Neon Tetra disease looks like. In every case, I’ve linked back to the source of the photo. If, for some reason, you wish to have your photo removed, please contact me.

Cleaning The Tank After An Infection

As mentioned, the problem with NTD is that once you have an infected fish in your aquarium, the disease will likely always be present in the tank, and some of the unaffected fish might just be carriers.

To truly get rid of it, you might need to strip down the entire tank, sterilize everything and cull your stock.

Is Neon Tetra Disease Contagious And Can It Spread To Other Fish?

Yes, this disease can infect a lot of other fish and while the list below is not an exhaustive list they are some of the most common to contract the disease.

List Of Fish That Can Catch Neon Tetra Disease

  • Angelfish
  • Rasbora
  • Guppies
  • Killifish
  • Barbs
  • Danios
  • Other Tetras

The critical thing to remember is that this disease can very easily spread through a community aquarium, highly contagious, and to save the other fish, you’ll need to remove any infected fish as soon as you notice any symptoms.

What Fish Are Immune To Neon Tetra Disease?

While some fish may not be as susceptible to this disease, I’m not sure of which fish are entirely immune. It has been said that Cardinal Tetras are somewhat resistant to this disease, but I’ve also heard of Cardinal Tetras showing symptoms and dying.

In fact here is a video from Neon Tetra Aquarist who has a Cardnal Tetra that has been infected.

Learn More About Neon Tetras:

Neon Tetra Disease, Signs, Symptoms, Prevention and Treatment

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