Neon Tetras Staying At The Top Of The Tank: Reasons & Solutions

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I became concerned when I observed my neon tetras swimming at the top of the tank for long periods of time. I worried that they might be suffering from swim bladder disease, but I wasn’t certain. Over time, I discovered that this behavior could be attributed to various factors.

Neon tetras typically stay at the top of the tank due to oxygen deficiencies. However this behaviour could also be attributed to swim bladder disease, which affects their buoyancy, ammonia spikes, and interactions with aggressive tankmates.

In this article, I will guide you through the process of treating neon tetras that frequently swim at the top of the tank, focusing primarily on swim bladder disease, which is the most common cause.

Also Read: Stress In Neon Tetras

Why Are My Neon Tetras Swimming At The Top?

It’s possible that neon tetras simply prefer the top of the tank. Just like humans, fish have individual personalities, so it’s important to consider their preferences.

However, before reaching any conclusions, it’s crucial to investigate the tank conditions. Generally, aquarists expect fish to swim in the middle of the tank.

If your neon tetras prefer the top, it’s important to ensure their overall health by ruling out negative factors that may drive them to the surface, including

1. Inadequate Oxygen Levels In The Tank

Several studies have explored the impact of reduced oxygen levels on fish behavior.

When oxygen levels decrease, fish may experience labored breathing and spend more time at the surface, as the top layer of water contains the highest concentration of oxygen.

Similar to humans, fish can suffocate if oxygen levels are insufficient.

Stronger fish will try to breathe from the surface, but if the oxygen deficiency weakens the neon tetras, they may lack the strength to stay at the top and eventually sink to the bottom, risking death.

While some research suggests that fish in low-oxygen environments can develop tolerance, this is more applicable to wild settings.

In an aquarium with prolonged low-oxygen levels, fish are more likely to experience long-lasting harm.

Also Read: Why Are My Neon Tetras Breathing Fast?

2. Neon Tetras Sharing A Tank With Aggressive Fish

Beginners might not expect fish to engage in aggressive behavior, assuming that they are peaceful creatures.

However, neon tetras are not the most dominant species in an aquarium. Larger and more aggressive fish, such as Oscars, Angelfish, African cichlids, and Tiger barbs, can pose a threat to neon tetras due to their delicate fins.

In a tank without sufficient hiding spots, neon tetras may seek refuge at the surface to escape the attention of these aggressive tankmates, especially if they are bottom dwellers.

Observe the behavior of your neon tetras and look for signs of aggression, such as bruising, lost scales, constant hiding, or loss of appetite.

Bullied neon tetras may stop eating to avoid conflicts with their tankmates during feeding times.

It is worth mentioning that in many cases bullied neon tetras will choose to stay at the bottom. It mainly depends on the living area of the attacking fish.

3. Neon Tetras With Swim Bladder Disease

Swim bladder disease affects a fish’s ability to swim properly. If the swim bladder functions deteriorate, the fish’s movement through the water is affected.

People often expect fish with swim bladder disease to stay at the bottom and exhibit abnormal swimming behaviors.

However, it’s important to note that this condition can also cause affected fish to float at the surface, preventing them from descending to the middle or bottom levels.

Swim bladder disease can be caused by various factors, including extreme temperatures, bacterial or parasitic infections, ammonia poisoning, and high nitrate levels.

4. Poor Water Conditions For Neon Tetras

Do you regularly clean your tank? Have you tested the pH levels and temperature? Incorrect parameters can cause discomfort, especially extreme temperatures.

Neon tetras are more likely to swim to the surface to escape poorly maintained tanks with extremely hot or cold water. Among these parameters, ammonia concentration poses the greatest danger.

Improper water conditions expose fish to infections that attack their gills. Neglected tanks also increase the risk of neon tetras developing swim bladder disease.

Ammonia spikes are particularly harmful as they directly harm the fish, causing burns on their bodies, including the gills.

A neon tetra in a tank with high ammonia concentration will struggle to breathe and will seek refuge at the surface to escape the ammonia’s harmful effects.

However, since they cannot leave the aquarium, the neon tetra will eventually die unless intervention occurs.

5. Neon Tetras Used To Being Fed At The Top

How do you feed your neon tetras? Do you sprinkle the food at the top of the tank? Neon tetras are observant creatures and will learn to associate your behavior with feeding time. 

Over time, they may swim to the surface during mealtimes, expecting food to be added to the water.

Some neon tetras may exhibit surface swimming behavior only when they are not being fed, while others demand food constantly, even when they are not hungry.

They will swim at the surface until they are fed.

What Should I Do If My Neon Tetras Stay At The Top?

The fact that neon tetras stay at the surface should be concerning, as some of the underlying factors may lead to their demise.

If your neon tetras are severely ill or distressed, you can utilize the following solutions to ensure their survival:

1. Improve Oxygen Levels

Neon tetras in oxygen-deficient tanks will experience a loss of appetite and labored breathing. You can address this issue by implementing the following solutions:

  • Perform a 50 percent water change to introduce fresh oxygen and promote water agitation.
  • Fill a jug with aquarium water and pour it back into the tank from a height. This process allows the water to collect oxygen as it descends and creates agitation. Increased agitation facilitates faster oxygen dissolution.
  • If low oxygen levels are due to high temperatures, use ice cubes in a sealed bag to reduce the water temperature. Additionally, deactivate the heater and switch off the lights.
  • Install air pumps and air stones in the aquarium. The Hygger Aquarium Air Stone Kit (link to Amazon) is recommended for this purpose.
  • Consider installing a more powerful filter that can adequately agitate the water.

Also Read: Do Neon Tetras Need An Air Pump?

2. Identify And Treat Potential Diseases

Identify the specific disease affecting your neon tetras and apply the appropriate treatment. 

For instance, in the case of swim bladder disease, start by performing a water change and thoroughly cleaning the tank.

A clean environment gives the fish the best chance of recovery. If the neon tetra is constipated, withhold food for three days before feeding it green-peeled, cooked peas.

Some people also add salt to expedite the healing process. You can refer to the video provided in the article for a demonstration:

Also Read: 17 Neon Tetra Diseases & Their Treatments

3. Improve Water Quality

Maintaining suitable water conditions is crucial for neon tetras. Ideal parameters include:

  • Temperature: 78-84 °F (25-29 °C)
  • pH: 6.8-7.8
  • Water hardness: 3-8 dKH (54-145 ppm)
  • Ammonia & nitrites: 0 ppm
  • Nitrates: <20 ppm

To measure ammonia, nitrate, nitrite, and pH levels, you can use the API Water Test Kit (link to Amazon), which provides accurate results within minutes and offers cost-effective testing for up to 800 measurements.

Ammonia levels above 0.25 can be lethal to fish. To address this, regular water changes are essential. A recommended practice is changing 15 to 20 percent of the water on a weekly basis.

If ammonia levels persist despite water changes, you may consider water conditioners such as Seachem Prime (link to Amazon).

Here are additional tips to achieve suitable water conditions for neon tetras:

  • Add sufficient plants and decorations to create hiding spots. Live plants like Amazon sword are preferable to artificial ones.
  • Choose a filter that matches the tank size in terms of strength.
  • Neon tetras require at least 20 gallons of water. Avoid overcrowding the tank.
  • Regularly vacuum the substrate.
  • Prior to performing a water change, check the water source to ensure it does not introduce toxins to the tank. Not all water sources are equal in terms of quality.

Also Read: Neon Tetra Tank Setup

4. Consider An Automatic Feeder

If your neon tetras swim to the surface due to hunger, refrain from adding food to the aquarium unless you consistently forget to feed them.

Some aquarists have a tendency to overfeed their fish, especially when the fish exhibit surface swimming behavior.

To avoid overfeeding or underfeeding, an automatic feeder can be a helpful solution.

The Zacro Automatic Fish Feeder (link to Amazon) is my personal recommendation, as it dispenses the correct amount of food at the same time every day once programmed.

This ensures a consistent feeding routine and prevents unnecessary overconsumption or hunger.

Automatic feeders are particularly beneficial for beginners who may be more inclined to feed neon tetras that exhibit surface swimming behavior, unaware that constant feeding can lead to health issues.

Also Read: How To Feed Neon Tetras

Why Do Neon Tetras Stay At The Top After A Water Change?

If you notice that your neon tetras stay at the surface, particularly after a water change, there are three primary concerns:

  • Temperature: Drastic changes in water temperature can cause neon tetras to seek refuge at the top to escape extreme conditions.
  • Toxins: If the new water introduces toxins such as chlorine and lead, the neon tetras will try to avoid the harmful effects by remaining at the surface. The 16 in 1 Drinking Water Test Kit (link to Amazon) can be used to check for these toxins.
  • Volume: Sudden and significant water changes can cause stress and discomfort for neon tetras, compelling them to swim to the top. These fish prefer stable conditions and are averse to drastic changes.


If you are in a rush, here is a quick summary of what I discussed earlier:

  • Neon tetras may stay at the top of the tank due to oxygen deficiencies, swim bladder disease, ammonia spikes, interactions with aggressive tankmates, or individual preferences.
  • Aggressive tankmates, such as Angelfish, Oscars, African cichlids, and Tiger barbs, can cause neon tetras to seek refuge at the surface.
  • Inadequate oxygen levels in the tank can lead neon tetras to stay at the top to access higher oxygen concentrations.
  • Swim bladder disease can impair the buoyancy of neon tetras, causing them to float at the surface.
  • Poor water conditions, including extreme temperatures and high ammonia concentrations, can prompt neon tetras to swim to the surface to escape discomfort.