Why Is My Neon Tetra Floating At The Top? (4 Handy Solutions)

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It’s alarming when fish show signs of distress. In some instances, I’ve observed my neon tetras floating near the top of the tank. With time, I discovered what instigates this issue and how to mitigate it.

Neon tetras might float at the top due to a condition known as swim bladder disease, which impacts the fish’s buoyancy. This typically occurs when the neon tetra ingests air, is constipated, or is grappling with an underlying infection.

In the following, I will guide you on how to handle a neon tetra that consistently floats at the surface. This involves addressing swim bladder disease and tweaking the water parameters utilizing the API Aquarium Test Kit (link to Amazon).

Why Is My Neon Tetra Floating At The Top?

Most people wouldn’t be concerned if they spotted their catfish or lionfish floating upside down as such behaviors are quite usual in specific fish.

However, it’s unexpected in neon tetras, hence, if your neon tetra exhibits such behavior, you should consult a vet.

This symptom typically indicates that the fish’s buoyancy is compromised, and you need to identify the root cause. There are several possible causes, including:

1. The Neon Tetra Has A Swim Bladder Disease

This is the prevalent cause of unusual swimming behavior in fish. The swim bladder regulates a fish’s movements in the water.

So, if it’s damaged, its function will be affected, altering the fish’s movement. Swim bladder disease is prompted by a range of causes, such as:

  • Air Ingestion – Neon tetras can ingest air while feeding at the surface. Sometimes, they consume so much air that it expands their stomach. An enlarged stomach can apply pressure on the swim bladder, thereby affecting its functionality.
  • Constipation – Overfeeding or feeding poor-quality food to your neon tetras can lead to a blockage in their digestive tract. Constipation causes the stomach to press on the swim bladder, reducing its width and impacting the neon tetra’s buoyancy.
  • Inappropriate Diet – If the diet of your neon tetra includes freeze-dried foods and dry pellets, they will expand in the fish’s stomach, causing it to press on the swim bladder.
  • Temperature – Low temperature can cause constipation in fish as it slows down the digestion process. This means a neon tetra’s digestive tract can become blocked even with a proper diet of high-quality foods in suitable amounts.
  • Infections – Sometimes, the swim bladder doesn’t function properly due to bacterial or parasitic infections. Introducing new fish, plants, or decorations can bring harmful bacteria and parasites into the tank.
  • Poor Tank Maintenance – This can also lead to infections of the swim bladder. A dirty tank filled with toxins weakens a neon tetra’s immune system, making the fish more prone to diseases and infections.
  • Trauma – Do you have aggressive fish in your neon tetra tank? A clash between fish can cause serious damage to the swim bladder. Neon tetras can also injure this organ by accidentally bumping into the walls and objects in the tank.
  • Nature – Some neon tetras are born with deformed swim bladders. Such fish can lead content lives even while floating upside down, as they are accustomed to their deformed swim bladder’s effects. They won’t cause much of a problem because you would have noticed their abnormal swimming behavior from birth.

Also Read: Neon Tetra Swim Bladder Disease

2. Your Neon Tetra is Searching For Food

Some neon tetras might float because they’re seeking food on the water’s surface.

You may notice this in neon tetras that aren’t receiving adequate food. If they’re hungry enough, they will invert to search for food at the surface.

3. The Neon Tetra is Bloated

Bloating is relatively easy to identify. Simply observe your neon tetra. You can quickly ascertain whether its abdomen is swollen.

A bloated body can throw off a neon tetra’s balance, preventing it from swimming normally and causing it to flip upside down or sink to the bottom.

Also Read: Why Is My Neon Tetra Swimming Upside Down?

Bloating has multiple causes, including:

  • Overfeeding – Similar to humans, neon tetras can be overfed, causing them to gain weight. Fish often act like they are hungry even when they are full. Overfeeding them in response to their behavior can result in bloating.
  • Constipation – Just as in humans, fish can become constipated. Once their digestive system becomes blocked, they will stop excreting waste, and their abdomens will swell. The resulting expansion can throw off their balance.
  • Worms – Camallanus worms can cause bloating by infecting your fish to the point where you can see them protruding from the anus.
  • Dropsy – Dropsy is a severe disease from which very few fish recover. Symptoms include bloating and raised scales.
  • Eggs – If your neon tetra is female, it may appear bloated because it is full of eggs. This is not a problem as the bloating will subside once the neon tetra lays its eggs.

What To Do If Your Neon Tetra Floats At The Top?

First, confirm that the neon tetra is still alive.

You can do this by stimulating it, for instance, touching it, adding food to the tank, changing the water, etc. If the fish doesn’t respond, it is likely dead.

But if it is still alive, you can employ the following methods to address the factors causing it to float:

1. Treating Swim Bladder Disease

Swim bladder disease has several solutions and remedies, including:

  • Temperature Increase – As you’re now aware, a low temperature slows digestion, which is why it’s recommended to raise the temperature by a few degrees. If you own a heater, it won’t take long to achieve this. For small tanks or bowls without a heater, you can use a heating pad.
  • Fasting – If the fish is constipated, cease feeding it for three days. This will give the neon tetra time to digest the food already in its stomach. The fasting period will allow the expanded stomach to shrink back to its original size due to constipation. For some neon tetras, fasting is all they need to recover from swim bladder disease.
  • Food – If your neon tetras remain sick despite fasting, after the three days, feed them peas. Ensure they’re cooked and peeled. Peas are high in fiber and can alleviate constipation swiftly.

When you resume the neon tetra’s regular diet, avoid overfeeding. The fish should only eat two or three times a day, consuming food that it can finish in a few minutes.

Ensure the food sinks before the fish eat it by pre-soaking it, particularly flake food. If they eat from the surface, they will ingest air.

  • Infections – If you suspect an infection caused the swim bladder disease, consult a vet. They will identify the offending bacteria or parasite and prescribe a solution. Regardless, isolate the fish.
  • Conditions – Keep a clean tank with the appropriate pH and hardness. Utilize water conditioners to remove chlorine, ammonia, nitrites, and other toxins. Neon tetras with physical injuries need a conducive environment to recover.

2. Adjusting the Neon Tetra’s Environment

Neon tetras in such situations need a clean, well-maintained tank to recover. Consider the following:

Water Parameters – Keep the pH between 7 and 8, the temperature between 74 and 80 degrees Fahrenheit, and the alkalinity between 54 and 180ppm. Install a heater if you don’t already have one for more precise control of the temperature.

I personally use the API Aquarium Test Kit (link to Amazon) to measure the pH, nitrates, nitrites, and ammonia. This bundle offers over 800 measures with high accuracy. I also use the API TAP WATER CONDITIONER (link to Amazon) when changing the water.

For maintaining temperature, I prefer heaters that do not create fluctuations as these can stress the fish and harm their health. The Orlushy Submersible Aquarium Heater (link to Amazon) works excellently for me.

  • Cleaning the Water – You’ll need a robust filter to keep the water clean. Weekly water changes (at least 10 percent) are also recommended. For larger tanks (20 gallons and more), replace 15 to 20 percent of the water each week.
  • Tank Size – The tank size will depend on the size of your neon tetra. Some can survive in a 10-gallon tank, while others need 75 gallons. The size you select doesn’t matter as long as it’s suitable for your specific neon tetra. Always avoid overstocking and overcrowding.
  • Environment – The layout of the aquarium environment is more crucial than you might realize. Stress can impact a neon tetra’s health, making it more prone to diseases that can harm the swim bladder. Hence, you should add plants, caves, logs, and the like to the tank. They provide hiding places, ease the neon tetra, and reduce stress.
  • Food – The diet should match the neon tetra’s preferences. Some neon tetras eat algae, others are carnivorous, and some feed on wood. It’s worth doing some research before introducing a specific neon tetra to your aquarium.

Ensure you know what it likes. A sick and stressed neon tetra can only recover if it’s fed high-quality food in appropriate quantities.

If you often miss feedings, the Eheim Automatic Feeding Unit (link to Amazon) could be a useful consideration.

  • Tankmates – Keep neon tetras with fish of a similar size. They also need peaceful neighbors that are unlikely to bother them. Suitable options include Oscars, Corydoras, Gouramis, and Otocinclus Catfish, among others.

3. Addressing Bloating in Neon Tetras

If your fish is bloated due to dropsy, it will likely not survive. Most vets agree that it’s too late to save a fish with an already swollen belly.

If the neon tetra’s scales aren’t raised, Camallanus worms could be the cause. Fenbendazole or levamisole-based products can treat them.

For a bacterial infection, you can use Maracyn or any other available antibiotic.

Regardless of what your fish is suffering from, it’s best to quarantine any fish that appears unwell to prevent potential diseases from spreading.

4. Properly Feeding Neon Tetras

If your neon tetra is floating due to hunger, but you consistently provide sufficient food, remember that neon tetras are nocturnal and more active at night.

Thus, you should add food to the tank after turning the lights off. This ensures the neon tetras are fed.

If you only feed during the day, the other fish may consume all the food while the neon tetra sleeps.

Do Neon Tetras Float When They Die?

Yes, neon tetras float when they die. This is due to the decomposition process producing gases that fill the fish’s stomach.

Since gas is lighter than water, dead neon tetras float. Eventually, the gas will dissipate, and the deceased fish will slowly sink to the bottom of the tank.


Here is a brief summary of what I discussed above:

  • A neon tetra floating at the top could indicate a health issue such as swim bladder disease, a bacterial infection, or it could be a sign of overfeeding and bloating.
  • Maintaining optimal tank conditions including temperature, pH, and cleanliness can significantly improve the health and lifespan of neon tetras.
  • Neon tetras should be fed a diet tailored to their specific needs, and nocturnal feeding may be necessary to ensure they receive enough nourishment.
  • It is crucial to select suitable tank mates for neon tetras to reduce stress and avoid potential harm.
  • If a neon tetra appears unwell or starts to float, it should be quarantined immediately to prevent possible disease spread to other fish in the tank.