Why Are My Neon Tetras Dying?

Your neon tetras are likely dying due to several causes such as a lack of a well-maintained tank, not enough food, or overcrowding.

Another likely cause of your bright-colored fish’s death could be loneliness. Neon tetras are shoaling fish and need to be in groups of at least six to thrive.

Stick around to learn more about why your neon tetras are dying and what you can do to prevent any future deaths.

Why Are My Neon Tetras Dying?

Neon tetras are hardy fish with a peaceful and timid temperament. Despite their high hardy levels, they’re not completely immune from certain issues.

That being said, here are some of the likely reasons why your neon tetras are dying.

Low-Quality Tank Care

With any aquarium, you need to ensure that the water purification system is intact. Otherwise, a dirty tank filled with fish waste could increase ammonia levels, which would, in turn, harm your neon tetras.

To make sure the water levels are adequate for the tropical fish, the pH needs to be between six and seven. In terms of temperature, the freshwater fish prefers a 72 to 76-degree F range.

If these needs aren’t met, the neon tetras will likely not survive for long. In addition to this, you need to clean the water periodically from any floating debris.

Neon Tetra Close Up

Stress Factors

Fish, like us, also experience stress. Neon tetras are naturally social creatures that swim in schools.

If you isolate them into less than six per tank, you’ll likely witness their death soon after. When not in a group, they tend to feel lonely and scared.

Stress, in turn, can play a crucial role in their death. Luckily, several signs can pinpoint their stress early on.

For instance, if they’re constantly hiding, it could be out of fear from other bullying fish. In other cases, your neon tetras may be glass surfing.

This often occurs when the small fish swims frantically up and down the tank, hoping to escape. It usually means the tank is too small and you may need to provide a larger, more accommodating space.

Another sign to watch out for is weight loss. A loss of appetite is a critical indicator that your neon tetras are experiencing stress.

Environmental Changes

Environmental changes mainly refer to constant water changes. While the process ensures a clean water space for your neon tetras, too much of it can put too much stress on the little guys.

If you change out too much water at once, it causes a shock reaction from the school of fish, resulting in lots of dying tetras.

As a rule of thumb, you should change out 10 to 15% of the water in your tank every week. If the water conditions are too poor for a weekly change, then you can pour out a bit more every other day.


A likely cause of death of your neon tetras could be that you’re overfeeding them. The torpedo-shaped fish only need to consume 2% of their body weight each day.

In other words, you mainly need to feed them two to four times daily. Now, overfeeding won’t necessarily kill your neon tetras due to them being overstuffed.

Instead, the fish will likely defecate more frequently. Consequently, the tank will be filled with more toxins than usual, which may cause death for some of your tetras.


A highly likely cause of your tetras’ death could be disease contamination. This could occur due to several reasons such as failing to filtrate the water consistently.

Neon Tetras Disease

The red-blue streaked fish may be affected by the neon tetras disease. This illness is rooted in a microsporidian parasite.

It may be difficult to diagnose this disease since it’s degenerative or starts slow, then progresses to become more lethal. Symptoms of this condition may include:

  • Loss of coloration
  • Restlessness
  • Lumpy body
  • Curved spine
  • It becomes hard to swim
  • Bloating
  • Fin rot

Neon tetra disease is often caused when your tetras ingest parasite-infested live food or dead fish. This illness is highly contagious since it travels through spores.

Two Neon Tetras

Ich Disease

Another parasitic disease worth looking out for is Ich or White Spot. You can tell your tetras are affected by this disease due to the prominent white spots around their body.

Other symptoms may include:

  • Fish flashing or scratching their body against nearby objects
  • Lethargy
  • Bruising due to constant flashing

Aside from the symptoms, the causes of Ich in your neon tetras could be plenty. For example, you may be using a contaminated tool for several tanks at a time.

Additionally, you may be adding plants with ich tomonts or protozoan latching onto them.

How to Prevent Death in Your Neon Tetras

The good news is that you can avoid these death-causing occurrences from happening.

Clean Your Tank

This should be your top priority. A clean tank will vastly reduce the likelihood of death in your neon tetras.

You can check your water parameters such as pH, ammonia levels, and temperature, every so often to make sure they’re suitable for the tetras.

In addition to this, you’ll want to vacuum the tank’s substrate from any food leftovers or waste. If you want to ensure a clean tank, you can add shrimp to act as leftover cleaners.

You can also add live plants to purify your water and provide more oxygen levels.

Avoid Purchasing Sick Fish

To steer clear of any parasitic diseases, try to avoid buying sick fish. To rule out any sick tetras, you’ll have to quarantine the new fish for a couple of weeks to monitor them for any signs of illness.

That being so, we highly recommend purchasing your supply of neon tetras from a reliable source.

Keep Your Tetras Company and Comfortable

To avoid any loneliness, always keep a school of at least six neon tetras. Aside from that, make sure the tetras are properly accommodated.

In other words, make sure the tank has plenty of room for the little fish to swim around freely. For instance, a 20-gallon tank can handle 10 to 13 neon tetras.

To Conclude

Why are my neon tetras dying? In brief, your neon tetras are likely dying due to multiple factors. It could be an unkempt tank, parasitic diseases, water shock, or loneliness.

To avoid these issues, you mainly need to guarantee a healthy feeding pattern, a consistent tank cleaning routine, and avoid overcrowding the tank.

That way, your neon tetras will enjoy a much longer two to three years of life.