Do Neon Tetras Need A Heater? (With Recommendations)

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Neon tetras are one of the most common fish in home aquariums, mainly because of their colors and peaceful nature.

But setting up a neon tetra tank could raise some questions, especially if these creatures actually need a heater (being pretty tolerable).

In this article, I will answer this question and also guide you on how to pick the right heater for your neon tetras. Let’s dive right in.

Why Do Neon Tetras Need A Heater?

Neon tetras need a heater mainly for the following reasons:

  • Tropical Origin: Neon tetras originate from warm, tropical environments in South America, specifically from the Amazon river basin. Their bodies are accustomed to stable, warm water conditions.
  • Temperature Regulation: The heater helps to maintain a consistent temperature in the aquarium, which is critical for the well-being of the neon tetras. They prefer water temperatures between 70 to 81 degrees Fahrenheit (21 to 27 degrees Celsius).
  • Metabolism Support: The right temperature helps to maintain the metabolism of the neon tetras at an optimal level. Cold water can slow down their metabolism leading to lethargy and decreased appetite.
  • Preventing Stress: Sudden changes in water temperature can cause significant stress for neon tetras, which can lead to disease and even death. Heaters prevent such sudden fluctuations.
  • Disease Prevention: Many diseases and parasites are more likely to proliferate in colder water. Keeping the water at the proper temperature helps to minimize these risks.
  • Reproduction: If you’re planning on breeding neon tetras, a stable, warm water temperature is essential for encouraging spawning behavior and ensuring the survival of fry (baby fish).
  • Overall Comfort: Just as humans prefer certain environmental conditions, so do neon tetras. Providing a heater for their tank helps to mimic their natural habitat, providing them with a more comfortable and suitable living environment.

Also Read: Neon Tetra Tank Setup

What Is The Optimal Water Temperature For A Neon Tetra Tank?

The most suitable temperature range for neon tetras is between 72 and 80 degrees Fahrenheit. As tropical fish, neon tetras need warm water in their aquarium.

While I typically encourage you to keep the temperature stable, you don’t have to be too strict about it. Neon tetras are hardy and can handle mild fluctuations.

Choosing The Right Heater Power For Your Neon Tetras

When picking a heater for you neon tetras, it’s worth considering these beforehand:

  • Tank Size: The heater’s wattage should be appropriate for the size of your tank. As a general guideline, you’ll need 3-5 watts per gallon of water.
  • Heater Type: There are several types of heaters including submersible, in-filter, and under-gravel. Submersible heaters are often recommended for their consistent heat distribution.
  • Temperature Control: Ensure the heater has an adjustable thermostat. This will allow you to set the heater to the optimal temperature for your neon tetras and make adjustments as necessary.
  • Temperature Accuracy: Look for a heater that maintains the temperature with high accuracy. High-quality heaters will keep the temperature stable, without fluctuations.
  • Safety Considerations: A reliable heater should come equipped with essential safety mechanisms. These could include an auto shut-off function that activates when the water level decreases or if the heater is taken out of the water, along with protection against overheating.
  • Durability: Heaters made from durable materials, such as shatter-resistant glass, will last longer and be safer for your fish.
  • Visibility of Temperature Setting: It should be easy to see and adjust the temperature setting on the heater. Some heaters also have lights to indicate when they are actively heating.
  • Reviews and Reputation: Consider the reviews and reputation of the heater and the brand. Opt for a reputable brand with positive reviews to ensure quality and reliability.

My personal recommendation: Tetra Submersible Heater (link to Amazon).

As a general rule, consider 5 watts per 1 gallon of water volume:

Tank SizeHeater Power
5-Gallon25 Watts
10-Gallon50 Watts
20-Gallon100 Watts
25-Gallon125 Watts
40-Gallon200 Watts
50-Gallon250 Watts
75-Gallon600 Watts (2 x 300 W)

Also Read: Neon Tetra Tank Size

Four Heater Types For A Neon Tetra Tank

You can choose from four types of aquarium heaters for your neon tetra tank. Yet, bear in mind that not every heater will suitable for your tank setup.

Keep reading to discover the best type of heater for your neon tetra tank.

1. Filter Heater

  • These heaters are integrated into the aquarium’s filter, heating the water as it passes through.
  • They help to ensure a uniform temperature throughout the tank by using the filter’s water flow.
  • They’re often easier to maintain since they’re out of sight and not directly in the tank.

2. Substrate Heater

  • These heaters are placed beneath the substrate or gravel at the bottom of the tank.
  • Substrate heaters are great for promoting plant growth in planted aquariums as they encourage the circulation of nutrients.
  • However, they can be tricky to install or adjust since they are located under the substrate.
  • They may not be suitable for tanks without substrate or for fish that like to dig.

3. Submersible Heater

  • These heaters are submerged completely in the water, often attached to the aquarium wall with suction cups.
  • They provide consistent and efficient heating, making them popular among many aquarists.
  • Temperature settings are usually easy to adjust, and they often come with a visible temperature display.

4. Hang-On Heater

  • These heaters hang on the side of the tank, partially submerged in the water.
  • They’re easy to install and adjust, but may not provide as consistent heating as submersible models.
  • They’re typically more affordable and a good option for smaller tanks or beginner aquarists.

What If Neon Tetras Are Kept In Extremely Cold Water?

Neon tetras thrive in tropical climates with warm waters. Therefore, keeping them in cold temperatures can lead to some issues:

  • Slowed Metabolism: Lower temperatures can slow the metabolic rate of the fish, leading to decreased activity and less eating. This can eventually result in malnutrition and weakened immune systems.
  • Color Fading: One of the most noticeable effects of cold stress in neon tetras is color loss. Their vibrant, beautiful colors can fade when they are kept in an environment that is too cold.
  • Disease Susceptibility: Cold temperatures can weaken the immune system of neon tetras, making them more susceptible to infections and diseases.
  • Stress: Significant changes in temperature or temperatures outside of their preferred range can cause stress for neon tetras, which can ultimately lead to more serious health issues.
  • Reduced Lifespan: Consistently low temperatures can reduce the lifespan of neon tetras. The stress and potential disease brought on by cold conditions can lead to a shortened life expectancy.
  • Lethargy: Neon tetras in cold water may become less active or even lethargic. This change in behavior is a clear sign of discomfort or illness.
  • Breeding Issues: If you’re trying to breed neon tetras, colder temperatures may deter spawning behavior. In extreme cases, it could even lead to the death of eggs or fry.

What If Neon Tetras Are Kept In Very Hot Water?

Hot temperatures (above 85 degrees Fahrenheit) are equally harmful to neon tetras:

  • Increased Metabolism: Elevated temperatures can speed up the metabolic processes in the fish, potentially causing stress and a rapid consumption of their energy stores.
  • Reduced Oxygen Levels: Warmer water holds less dissolved oxygen, which can lead to difficulties in breathing and may potentially cause suffocation.
  • Disease Susceptibility: Just as with cold temperatures, excessively high temperatures can weaken the immune system of neon tetras, making them more prone to diseases.
  • Stress: Severe heat can cause extreme stress for neon tetras, leading to erratic behavior and potentially even death.
  • Reduced Lifespan: Chronic exposure to high temperatures can decrease the lifespan of neon tetras. This is often a result of ongoing stress and increased susceptibility to disease.
  • Increased Aggression: Some fish, including neon tetras, may become more aggressive if the water is too warm. This can disrupt the harmony in your tank and cause injury to your fish.
  • Color Fading: Similar to cold stress, heat stress in neon tetras can lead to color loss. Their vibrant colors may fade in an environment that is too hot.
  • Breeding Issues: While slightly warmer temperatures can encourage breeding, extremely high temperatures may harm the eggs or fry, or deter spawning altogether.

What If Neon Tetras Experience Sudden Temperature Changes?

Neon tetras are highly sensitive to sudden temperature changes, mainly due to:

  • Stress Induction: Rapid temperature fluctuations can cause immediate stress for fish, disrupting their normal behavior and potentially leading to erratic swimming patterns or hiding behavior.
  • Immune System Suppression: The stress from sudden temperature changes can suppress the fish’s immune system, making them more susceptible to diseases and infections.
  • Thermal Shock: In extreme cases, a very sudden and drastic change in temperature can result in thermal shock. This can be fatal for fish, as their bodies cannot adapt quickly enough to the new conditions.

Can I Keep Neon Tetras Outdoors?

I am usually against keeping neon tetras outside unless you live in a climate that consistently maintains temperatures within their preferred range (70-81 degrees Fahrenheit or 21-27 degrees Celsius) without drastic fluctuations.

Even in such climates, you need to consider other factors like potential exposure to predators, changes in water chemistry due to rain or debris, and ensuring the tank or pond is well-maintained.


The recommended temperature range for a neon tetra tank is between 72 and 80 degrees Fahrenheit.

While these fish are considered hardy, the temperature shouldn’t fluctuate too much. That is why using a heater in their tank is my general rule of thumb.