neon tetras

Neon Tetra Temperature Guide: The Ideal Range for Healthy Fish

Water temperature that’s too hot or cold is bad news for neon tetra fish. That’s because extreme temperatures can harm them by negatively affecting their metabolism, weakening their immune system, and deteriorating their overall health.

And as a responsible neon tetra owner, it’s up to you to know the right water temperatures needed for them to thrive alongside other fish. Don’t make the mistake of assuming the temperature is okay simply because you live in a warm climate.

This comprehensive guide will help you understand how to do that, including determining ideal tank water temperatures for neon tetras, and how to maintain the right temperature and avoid the effects of water fluctuations. I’ll also highlight the signs of temperature stress and what to do should your neon tetras be affected.

Key Takeaways

  • Temperature fluctuations can affect the behavior, metabolism, feeding, activity, and health of neon tetras.
  • The ideal temperature range for juvenile and adult Neon Tetras is between 72-78°F (22.2 – 24.4°C). 
  • For breeding, the ideal temperature is between 75-78 °F (23.9 – 24.4°C).
  • Using an aquarium heater is the best way to maintain the ideal temperature for neon tetras.

Why Temperature Matters with Neon Tetras

Before I get into the ideal temperatures for neon tetras, it’s important you understand how extreme temperatures affect them and the risks associated.

How Temperature Affects The Behavior Of Neon Tetras

Like all living organisms, temperature can affect neon tetras in several ways, such as:

  • Growth: Extreme temperatures can stunt growth in neon tetras by disrupting their metabolism, feeding, digestion, and breathing capacity. 
  • Breeding and reproduction: Neon tetras won’t breed in cold temperatures, which is likely an evolutionary adaptation since extreme temperatures affect embryonic development.
  • Longevity: In less-than-ideal temperatures, your neon tetra is likely to fall ill due to poor metabolism. If nothing is done to remedy the aquarium temperature, it could shorten your neon tetra’s lifespan.

Water Temperature’s Impact on Feeding, Metabolism, and Activity

When the temperature is too cold, your fish’s metabolism slows down and reduces the rate of food digestion. Slower digestion then reduces their activity levels and even makes breathing more difficult for them.

In contrast, warmer temperatures will increase neon tetras’ metabolism which makes them more active. Having a fast metabolism isn’t necessarily bad, but your fish can become so hyperactive that they’ll consume more oxygen, which can be harmful if tank oxygen is already running low.

Risks of Temperature Fluctuations

Here are a few risks associated with temperature fluctuations on neon tetras:

  • Weakened immune system: Frequent water temperature fluctuations can weaken your fish’s immune system which can leave them vulnerable to diseases and even death.
  • Neon Tetra disease: With a weakened immune system, neon tetras become more vulnerable to neon tetra disease,  which is incurable and highly contagious.
  • Impaired metabolism: Temperature can slow or quicken your fish’s metabolic rate which can affect their energy balance.
  • Suffocation: Hot temperatures cause neon tetras to use more oxygen, leading to suffocation if it runs out in the tank. In addition, as water temperature increases, the amount of oxygen it can hold decreases, resulting in less overall oxygen available for your fish.
  • Harmful bacteria and parasite growth. Warm water provides ideal conditions for harmful bacteria and parasites to thrive. These organisms can easily take over your neon tetra tank and cause health problems like swim bladder disease or fin rot.

What Is the Ideal Temperature Range for Neon Tetras?

The ideal neon tetra temperature range is between 72-78°F (22.2 – 24.4°C). Neon tetras thrive best in warmer waters (but not too warm!) as they are tropical fish. That said, neon tetras can be quite sensitive to temperature changes so you need to maintain the right range at all times.

The temperature range is the same for both adults and juveniles. For breeding, the temperature should be slightly higher between 75-78 °F (23.9 – 24.4°C).

Signs of Temperature-Induced Stress in Neon Tetras

Unfortunately, our aquatic buddies can’t tell us when it’s too hot or cold. But luckily, there are a few behavioral and physical signs of temperature-induced stress we can watch out for.

Behavioral Signs of Temperature Stress in Neon Tetras

  • Reduced activity: In cold temperatures, you may notice that your neon tetras are more sluggish or become dull.
  • Increased activity: When the temperature is hot, your fish may become hyperactive and seem agitated or stressed.
  • Gasping near the water surface: This is a tell-tale sign of low oxygen in the tank. It may be due to high water temperatures or poor water quality.
  • Reduced appetite:  Temperature fluctuations may impair your tetra’s appetite due to its slower metabolism.
  • Disrupted breeding: Temperature affects neon tetras breeding because they won’t breed in cold temperatures or very hot temperatures. Moreover, cold temperature can retard the rate of embryonic development and higher temperature accelerates it.

Physical Symptoms of Temperature Stress in Neon Tetras

  • Shivering or twitching:  While neon tetras may shiver or twitch for various reasons, frequent twitching could be a sign of cold water temperatures.
  • Color change: Stress from temperature fluctuations can cause unexpected color changes in neon tetras, so you may notice a new paleness in your fish.
  • Disease: Extreme temperatures make neon tetras more vulnerable to physical illness and disease like fin rot, neon tetra disease, or ICH diseases.
  • Physical ailments: Not only does temperature fluctuations make neon tetras more lethargic or hyperactive, but extreme temperatures can cause shock or organ failure.
School of neon tetra fish

How to Maintain the Right Temperature in Your Tank

Temperature fluctuations are normal in aquariums. But when caring for neon tetras, you need a way to get their temperatures right at all times.

You can do this by simply keeping the aquarium in a room with ideal temperatures or avoiding direct sunlight. However, these methods aren’t effective in the long term, especially during weather changes.

Your best option is to use an aquarium heater which allows you to regulate temperature with accuracy, monitor the tank temperature, and prevent extreme temperature fluctuations. 

To choose an aquarium heater, consider the following:

  • The size of your tank: Bigger aquariums require larger heaters with more wattage.
  • The type of heater: Is it adjustable or pre-set? Can it be used for freshwater or saltwater fish? Is it made of titanium, plastic or glass (which can easily break)?
  • Durability: Go for durable heaters that don’t break easily, explode, or corrode.
  • Features: The best aquarium heaters come with features like automatic shutoff, overheat protection, and built-in thermostat. 
  • The price: Ideally, you’d want an aquarium heater that offers you the best value for your money. Plus, a costly heater doesn’t necessarily mean a better one.

With these factors in mind, I’d recommend these two affordable aquarium heaters that tick all the right boxes:

🐠For more information on choosing the best aquarium heater, review our comprehensive aquarium heater guide.

HITOP Adjustable Aquarium Heater

Besides its affordable price starting at just $15.97, the HITOP Aquarium Heater is a great product overall. This adjustable budget-friendly heater comes with a thermostat for monitoring the temperature and an automatic turn-off feature for regulating the temperature.

Although the HITOP heater is made of glass, it uses 2mm thickened quartz glass which is 33% thicker than normal aquarium heaters of its level. It comes in different sizes (25W, 50W, 100W, 200W, 300W), so pick the size that’s suitable for your tank.


  • Affordable
  • Made of glass, so no risk of electrocution


  • Glass heaters are prone to cracking, breaking, exploding.
  • Not as reliable as higher end aquarium heaters

INKBIRDPLUS Titanium Aquarium Heater

The INKBIRDPLUS Titanium Aquarium Heater is a powerful heater made for larger tanks with 50-60 gallons. But what we really love about the IINKBIRDPLUS is its quality.

For one, the INKBIRDPLUS’s titanium body offers the advantage of an anti-breaking, anti-explosion, anti-cracking, and anti-corrosion aquarium heater. It allows for increased accuracy with its double-sensing probe for detecting temperature and water volume. 

Moreover, it provides an accurate thermostat in addition to overheating protection, water shortage protection, and automatic shutoff feature.

The INKBIRDPLUS  is truly a top-quality aquarium and it has obtained the CE, FCC, and ROHS certifications to guarantee its quality.


  • Titanium body won’t corrode in water
  • Won’t easily crack or break making more durable than glass and plastic aquarium heater


  • Not built for smaller tanks
  • Pricier than others

In Case of an Emergency: How to Maintain the Right Tank Temperature Without an Aquarium Heater

Maybe you don’t have an aquarium heater yet, or perhaps it has been damaged. In either case, you’ll need to find a way to keep the temperature warm enough without a heater. Here’s what you can do:

Add Warm or Cool Water to the Tank

Depending on the temperature, add hot water to warm up the tank or cold water (or even ice cubes) to cool it down. Have a thermometer on hand for measuring the water temperature to avoid overheating or overcooling the tank.

Use A Heating Mat

Heating mats can be used in a pinch where you don’t have an aquarium heater. This option is better for small aquariums or fish bowls that can’t use a tank heater. If you decide to use a heating mat, ensure to place it where it won’t come in contact with moisture to prevent damage.

Note that because aquariums have glass bodies, they aren’t great heat conductors so using a heating mat may be inefficient or take longer than using a heater.

Increase the Room Temperature

The aquarium water’s temperature is affected by the room’s temperature. If you don’t have an aquarium heater, you can use a space heater or turn your thermostat up or down to regulate the water’s temperature. Just be sure to avoid placing your aquarium under direct sunlight.

Cover the Aquarium With a Lid

Water at the surface level comes in contact with air which cools it down. Covering the aquarium with a lid will help preserve heat in the tank.

Keep the Light On

Light emits heat, whichcan be useful for maintaining some heat in the fish tank. But remember: you can’t keep the aquarium lights on all day as it can disrupt your neon tetra’s  circadian rhythm.

Use a Heavy Blanket or Towel

You can try insulating your fish tank by wrapping it with a heavy blanket or towel to preserve heat. This method may be more effective for smaller fish tanks or aquariums.

Cool the Tank With a Fan

In hot climates or when the tank water temperature is getting too hot, use a fan to blow over the water surface to cool it down.

Neon Tetra Temperature FAQs

How cold is too cold for neon tetras?

Temperature below 72°F (22.2°C) is considered too cold for Neon Tetra fish.  This species of fish can be hardy so they might seem fine in cooler water, but cold temperatures still aren’t good for their well-being.

Do neon tetras need warm water?

Yes, neon tetras thrive in warm water because they’re tropical fish. To be specific, they need warm water within the range of 72-78°F (22.2 – 24.4°C). Be careful here because neon tetras are sensitive and water temperature that’s even slightly too hot can harm them.

Can neon tetras live in unheated tanks?

While neon tetras may do fine in tanks that haven’t been heated with an aquarium heater, it’s not advisable as cold temperatures can harm your fish. 

Why do my neon tetras keep dying?

Your neon tetras may be dying for various reasons that include extreme temperatures, stress, contamination, overcrowding, starvation, overfeeding, suffocation, and even attacks from other fishes. To determine the exact cause of death, it may be best to consult an aquatic vet.

🐠 For more reasons why your neon tetras might be dying, consult our full neon tetra care guide.

A Temperature Check

Neon tetras can be finicky about the temperature of their aquarium and to be great fish owners, it’s our responsibility to adjust and tweak it to ensure their home is in the best shape.

Aquarium heaters exist to properly regulate and maintain the water temperature, and in an emergency, use our tips and tricks until you get an aquarium heater. Remember to consistently check the water temperature to keep your neon tetras happy and thriving. 

Have you experienced temperature stress in your neon tetras? How did you handle it? Share your experience in the comments and be sure to share this article with a fellow neon tetra owner!

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