Can Neon Tetras Live in Cold Water?

If you’re new to keeping fish, you might think that it’s as simple as tossing your newly-bought scaly pals straight into an aquarium that you’ve filled up with tap water and treated with a water conditioner. Can Neon Tetras live in cold water? Water parameters vary from fish to fish because they are meant to mimic the natural environment where fish live in the wild. Neon tetras are found in the wild in the warm waters of the Amazon basin in South America. Because they come from naturally warm waters, they require warm water in aquariums as well, meaning that they cannot live in cold water.

Exposing your tetras to cold water can be harmful to their health, or even kill them, so should be avoided as much as possible.

Why Can’t Neon Tetras Live in Cold Water?

As tropical fish, neon tetras have adapted to live in warm water. Their biology requires them to maintain certain water parameters to keep them healthy. As a species, they have evolved to thrive in waters that are warmer. In particular, neon tetras require temperatures of between 72 and 80 degrees Fahrenheit to survive and thrive. While they can endure lower temperatures for periods of time, the cold will take a toll on the health of your fish.

What if I Put My Neon Tetras in Cold Water?

When neon tetras are in cold water, they rarely fare well. They may endure cooler temperatures in a pinch for a short period of time, such as if you lost power and could no longer warm up your water, but long-term, they will suffer. Cool water is typically defined as between 60 and 70 degrees Fahrenheit while anything under 60 degrees Fahrenheit would be considered cold.


Fish can go into shock when they are put into cold water. Even water that is just 60 degrees Fahrenheit is cold enough to potentially shock your fish enough to cause it to die after enough exposure. Neon tetras are quite fragile and they usually do not do well when put into cold water. Even if you were able to rescue your neon tetra from the water before death, there is a high likelihood of significant and permanent weakening of the fish that can dramatically reduce the lifespan.


Neon tetras can run into stress with cooler waters as well. When stressed out, you will also notice that their typically-vibrant colors start to fade due to stress. They also tend to move erratically during the time that they are stressed as well. This is especially common if your water starts to get too cold for comfort, or if you are moving fish from one water temperature to another, such as when adding new additions to your tank.

Do neon tetras sleep

Lowered metabolism

When water is not at the ideal temperature neon tetras suffer from lowered metabolisms. Fish are cold-blooded, so their own body temperature depends upon the temperature of their surroundings. When they start to get colder and their temperatures drop below 70 degrees Fahrenheit. Their bodies will slow down– both digestion and breathing will become difficult, and for longer periods of time, this can be fatal.

Fin rot

Cooler waters can also be dangerous for your fish, causing fin rot. When fish do not have their immune system working up to par, they can wind up suffering from fin rot– a serious condition in which the fish may experience fraying and rotting of the fins due to bacterial infection. As the fins rot, the fish may suffer from mobility problems or even fully succumb to the infection and die.

Ich and other diseases

Neon tetras may also be opened up to all sorts of other diseases as well when you keep them in cool or cold water.

Ich is a disease caused by a common aquatic parasite that causes white patches to grow all over the scales of many fish. It’s especially common in chain pet store aquariums, where they receive massive shipments of tropical fish to sell. Because stress increases vulnerability to ich, it can also be common if you keep your aquarium too cold. It will be easy to spot– just look for the white, fuzzy patches growing all over your fish’s scales.

Ich can kill your fish if you don’t treat it quickly– but it can also be treated relatively easily, so long as you keep the water warm enough to allow your neon tetras to have a properly functioning immune system.

(We have a guide on caring for neon tetras – check it out here!)

How Do I Keep My Aquarium Warm Enough?

Typically, most people don’t keep their homes warm enough to use the ambient air to keep their aquariums warm enough for neon tetras. If you keep your home at 68 or 72 degrees Fahrenheit, your water is probably right around that temperature as well, if not a bit colder. As a result, your fish will suffer. You will need to do something to keep your water warmer.

When keeping fish, the easiest way to keep your water up to temperature is to use a heater that will ensure that your water is just right. A heater paired with a thermometer will help you to keep track of exactly how warm or cold your aquarium is so you can make any necessary adjustments as needed.

Types of Heaters

Choosing the right kind of heater for your aquarium depends a lot upon what you really want. People commonly use three main types of heaters, though others exist as well. The common ones are submersible, substrate, and filter heaters.

Submersible heaters

As the name implies, submersible heaters are entirely submerged in the water and are usually anchored to the glass by suction cup somewhere in your aquarium. The heater is waterproof and is typically automatic. They warm up water rapidly, while also sensing to ensure that they do not heat up beyond whatever point they are programmed to.

However, you must make sure that you pick out the right size for your aquarium. They are usually rated by gallon sizes, and you would ideally get one that is within that range. Larger tanks, for example, require much more heating power than a small 10-gallon aquarium, so you would need a larger and stronger heater. Overall, submersible heaters tend to be favored because they usually perform better.

Substrate heaters

Substrate heaters are similar, but rather than having a tube sitting somewhere in your aquarium, you’ve got a flat heater that rests underneath the substrate.

If you want a more natural look to your aquarium, having the heater hidden could be what you want. They work well enough, but maintenance can be a bit more difficult because you have to move the substrate to access the heater. This could be problematic if you have a heavily-planted aquarium, as you’d have to disturb the roots.

Filter heaters

Filter heaters are positioned in the filter for your aquarium, hiding it from sight. Also called in-line filters, these will work on the pump of your filter. As water is filtered in your aquarium, it will flow through a tube, be warmed by a heater element, then pumped right back into the aquarium, warmer and ready to go.

If you want the convenience of being able to access your submersible heater without having to see it, this could be a great option for you. However, they are also a bit more expensive than other options and are entirely dependent upon water flow.

Choosing the Right Size

Because aquariums come in so many shapes and sizes, it’s important that you have enough heating power for any volume of water that you may have. If you, for example, have a 10-gallon aquarium with a single small school of neon tetras, you might only need one small heater.

However, if you have a massive 50-gallon community tank with several different schools of fish, you may need several heaters or something that is larger to ensure that you have the heating power to keep all of the water up to temperature.

When you purchase a heater, make sure you look at the gallon rating and try to find one that is as close as possible to your size. Just remember that you always keep a thermometer in your water as well so you can check to make sure that the water parameters are within range so you can fix any problems before they become fatal.

Can Some Fish be Kept in Cold Water?

While neon tetras can’t be kept in cold water, there are some species of aquarium fish that thrive without a heater. Goldfish are known for being cold-water fish and typically thrive without heaters, though they require much larger tanks and plenty of filtration.

Other fish, such as the white cloud mountain minnow, do well in cool water as well, while still providing you with a very similar look to neon tetras. If you want a splash of color in your tank without needing a heater, look for coldwater fish.

If you’re set on raising neon tetras, however, stick to running a heater. Your fish will thank you for it with vibrant colors and longer, healthier lifespans!

For a few suggestions on good tank mates for neon tetras, check out our Best Tank Mates for Neon Tetras guide!