Why Is My Neon Tetra Not Eating? (5 Easy Solutions)

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Neon tetras are among the most popular fish in home aquariums, and for a good reason – they are extremely beautiful and peaceful.

However, like any other fish, sometimes they present issues. For example, a few months ago, one of my neon tetras refused to eat, no matter how hard I tried.

In this article, I will explain why neon tetras may suddenly stop eating, and what steps you can take to overcome this problem.

Let’s dive right in.

Why Is My Neon Tetra Not Eating?

Just like humans, fish like neon tetras have eating habits that can be affected by a variety of factors:

1. Bad Water Conditions

The water quality of your aquarium can significantly impact the well-being and appetite of your neon tetra.

  • Ammonia Levels: High levels of ammonia, resulting from decaying plant material, fish waste, or uneaten food, can lead to a loss of appetite in neon tetras.
  • Incorrect pH: Neon tetras prefer slightly acidic water with a pH between 6.0 and 7.0. Deviations from this can cause stress, which can result in loss of appetite.
  • Hard Water: Neon tetras are sensitive to the hardness of the water. If it’s too hard, it can negatively affect their digestion and appetite.
  • Nitrate and Nitrite Levels: Elevated nitrate and nitrite levels can make neon tetras feel unwell, which can lead to a decrease in appetite.
  • Pollutants: Chemical pollutants, such as chlorine and heavy metals, can be harmful to neon tetras, causing them to stop eating.

2. Wrong Temperature

The right temperature is essential for the metabolic processes of neon tetras, which includes digestion:

  • Temperature Variation: Neon tetras thrive at a temperature between 70°F and 81°F (21°C and 27°C). If the water is too cold or hot, it may lead to a loss of appetite.
  • Sudden Temperature Changes: Rapid changes in temperature can stress neon tetras, affecting their feeding habits.
  • Constant Fluctuation: Regular, drastic temperature shifts can lead to metabolic disorders, which can reduce the appetite of a neon tetra.
  • Long-term Low Temperature: If neon tetras are exposed to lower temperatures for a prolonged time, they can become lethargic and stop eating.
  • Long-term High Temperature: Elevated temperatures for a prolonged period can cause increased metabolism and stress, leading neon tetras to eat less.

3. Stress

Environmental and physical stress can severely affect the feeding habits of neon tetras:

  • Companion Species: Neon tetras may experience stress and subsequent appetite loss if they share their tank with aggressive or unsuitable species.
  • Overpopulation: A crowded tank can lead to food and space rivalry, instigating stress and decreasing a neon tetra’s inclination to eat.
  • Handling Mismanagement: Frequent or harsh handling of neon tetras can generate stress, causing them to forgo their meals.
  • Insufficient Hiding Spots: Neon tetras require adequate hiding and resting places. A shortage of these can result in persistent stress and ultimately, a diminished appetite.
  • Absence of Routine: Inconsistent feeding and lighting patterns can produce stress and disorientation, negatively impacting the appetite of a neon tetra.

Also Read: Stress In Neon Tetras

4. Breeding

During the breeding process, neon tetras can undergo changes that may affect their eating patterns:

  • Pre-spawning Behavior: As neon tetras prepare to spawn, they may eat less or stop eating altogether.
  • Post-spawning Stress: After spawning, neon tetras may be stressed and exhausted, which can lead to decreased appetite.
  • Egg Binding: In rare cases, a female neon tetra might struggle to release her eggs, which can result in loss of appetite.
  • Parental Stress: Parenting neon tetras may focus on caring for eggs or fry, forgetting to eat in the process.
  • Nutrient Deficiency: During pregnancy, if a neon tetra is not provided with enough nutrients, she might stop eating.

5. Illness

Sickness can be a common reason for a neon tetra to lose its appetite:

  • Parasitic Infections: Parasites can cause discomfort and pain, leading to decreased eating in neon tetras.
  • Bacterial Diseases: Illnesses such as fin rot or columnaris can cause neon tetras to stop eating.
  • Fungal Infections: These can make neon tetras feel unwell, leading to loss of appetite.
  • Internal Blockage: If a neon tetra has an internal blockage, it might stop eating.
  • Visible Symptoms: Physical changes such as bloated body, faded colors, or clamped fins are often signs of illness, which can cause neon tetras to lose their appetite.

Also Read: Why Is My Neon Tetra Turning White?

How To Treat A Neon Tetra That Stopped Eating

As mentioned above, the health and eating habits of your neon tetra can be significantly affected by their environment and overall well-being.

Addressing these issues is a vital part of providing proper care. Let’s explore some more detailed and comprehensive actions that you can take:

1. Treating Bad Water Conditions

The quality of the water in your aquarium is fundamental to the health and appetite of your neon tetra:

  • Regular Water Changes: Perform bi-weekly water changes, replacing about 15-20% of the water to reduce harmful substances and replenish necessary minerals.
  • Employ a Water Conditioner: Use a water conditioner to neutralize potentially harmful substances such as chlorine and heavy metals. My recommendation: Tetra AquaSafe (link to Amazon).
  • Routine Water Testing: Consistently test the water using a reliable kit, allowing you to monitor parameters like pH, ammonia, nitrite, and nitrate. I personally use the API FRESHWATER MASTER TEST (link to Amazon).
  • Consistent Tank Cleaning: Regularly remove uneaten food, fish waste, and decaying plant matter to minimize ammonia buildup and improve water quality.
  • Maintain a Good Filter: Keep your filter system in top shape as it plays a crucial role in removing pollutants and maintaining clean, healthy water for your neon tetra.

Also Read: Do Neon Tetras Need A Filter?

2. Correcting the Wrong Temperature

Maintaining a stable and appropriate temperature is key to your neon tetra’s comfort and appetite:

  • Invest in a Reliable Heater: Use a dependable aquarium heater to maintain a temperature range of 70°F and 81°F (21°C to 27°C). My recommendation: Orlushy Submersible Aquarium Heater (link to Amazon).
  • Consistent Temperature Monitoring: Regularly monitor the temperature with an aquarium thermometer to prevent sudden fluctuations that could stress your neon tetra.
  • Gradual Temperature Adjustments: If temperature adjustments are necessary, ensure changes are gradual, around 1-2°F per hour, to prevent temperature shock in your neon tetras.

Also Read: Neon Tetra Temperature

3. Alleviating Stress

Reducing stress in your neon tetra’s environment is a key factor in improving their appetite:

  • Provide Abundant Hiding Spots: Incorporate plenty of plants, rocks, and aquarium decor to provide safe hideaways and reduce stress in your neon tetras.
  • Maintain Consistent Routines: Keep a consistent schedule for lighting and feeding times to create a predictable environment for your neon tetra, reducing stress.
  • Prevent Overcrowding: Stick to the rule of one gallon of water per one inch of fish to provide sufficient space and prevent stress from overcrowding.
  • Minimize Handling: Keep handling of your neon tetras to a minimum to avoid causing undue stress.
  • Choose Compatible Tank Mates: Ensure the tank mates of your neon tetras are non-aggressive and compatible, minimizing potential conflict and stress.

When it comes to delicate fish like neon tetras, I would suggest avoiding aggressive species like:

  • Oscars (Astronotus ocellatus)
  • Jack Dempseys (Rocio octofasciata)
  • Red Devils (Amphilophus labiatus)
  • Tiger Barbs (Puntius tetrazona)
  • Green Terror Cichlids (Andinoacara rivulatus)
  • African Cichlids (Various species from the Cichlidae family)
  • Bettas (Betta splendens)

Rather, prioritize peaceful species like:

  • Harlequin Rasboras (Trigonostigma heteromorpha)
  • Cardinal Tetras (Paracheirodon axelrodi)
  • Corydoras Catfish (Various species from the Corydoras genus)
  • Cherry Shrimp (Neocaridina davidi)
  • Zebra Danios (Danio rerio)
  • Endler’s Livebearers (Poecilia wingei)
  • Otocinclus Catfish (Otocinclus affinis)

Also Read: 19 Great Neon Tetra Tank Mates

4. Addressing Pregnancy

Providing careful care and attention during the breeding process can ensure your neon tetra continues to eat healthily:

  • Supply Nutrient-rich Food: During pregnancy, increase the nutritional quality of food for your neon tetra to meet their heightened dietary needs.
  • Prepare a Separate Breeding Tank: Consider setting up a separate breeding tank to reduce stress during the spawning process.
  • Careful Monitoring: Keep a close eye on your pregnant neon tetra to detect and address any complications early.

Also Read: Neon Tetra Eggs 101

5. Treating Illness

Prompt diagnosis and treatment of illnesses are essential to restore your neon tetra’s appetite:

  • Identify Signs of Illness: Regularly observe for symptoms such as bloating, color fading, or clamped fins to identify potential illnesses in your neon tetra.
  • Isolate Unwell Fish: Quarantine any unwell neon tetras to prevent potential spread of disease to other inhabitants of the tank.
  • Seek Professional Help: Consult a fish veterinarian for a proper diagnosis and treatment plan if your neon tetra appears to be sick.
  • Administer Appropriate Medication: Depending on the illness, administer the right medication as prescribed by a professional.
  • Maintain Tank Cleanliness: Regular cleaning of the tank can prevent recurrence or spread of diseases, fostering a healthier environment for your neon tetra.

Also Read: 17 Neon Tetra Diseases & Their Treatments

What Should I Feed My Neon Tetra If It Stopped Eating?

When your neon tetra has stopped eating, it’s important to stimulate its appetite with enticing, nutrient-rich options. Here are some potential food sources you can try:

  • Try Different Types of Flake Foods: Flake foods are a staple diet for neon tetras. If your fish isn’t eating, try changing the brand or type of flake food.
  • Offer Micropellets: These are small enough for neon tetras to eat and are packed with nutrients.
  • Introduce Live Foods: Foods like daphnia, brine shrimp, or bloodworms can stimulate appetite due to their movement and high nutritional content.
  • Frozen Foods: Like live foods, frozen varieties such as bloodworms, brine shrimp, and daphnia can be appealing to neon tetras. My recommendation: San Francisco Bay Brand Freeze Dried Bloodworms (link to Amazon).
  • Try Vegetables: Small amounts of blanched vegetables like peas or spinach can provide a change in diet and stimulate eating.
  • Feed at Regular Intervals: Neon tetras can become accustomed to a feeding schedule, which can encourage regular eating habits. Make sure to remove any uneaten food after a few minutes to maintain water quality.

Also Read: How To Feed Neon Tetras


A neon tetra that stopped eating shouldn’t be ignored. That is usually a sign of a more serious problem, such as unfavorable water conditions or disease.

Start by checking the water parameters, with ammonia, pH, and temperature in particular. Also, make sure you inspect your fish for potential diseases.

If you are not sure, consult an aquatic veterinarian. An expert will walk you through the right treatment in the most accurate way.