Do Goldfish Need A Heater? {Will Cold Water Kill Goldfish}

Goldfish are typically hardy fish, but do goldfish need a heater?

If they live in cold water will the cold water kill the goldfish?

Find out below.

Do Goldfish Need A Heater?

No, Goldfish are cold-water fish and they do not need a heater. You might only consider including a heater if the tank temperature is below the ideal range. In this case, the heater will function more in stabilizing the tank temperature than raising it.

However, it is essential to note that different goldfish types might have a slight variation in their temperature demands. Slim-bodied goldfish type can tolerate temperature slightly below or above freezing points.

On the other hand, fancy goldfish cannot tolerate water temperatures below 550F. However, every type of goldfish needs to be in a stable tank with a suitable temperature.

do goldfish need a heater

What Temperature is Ideal for Goldfish?

Temperature is one of the crucial parameters in a goldfish tank. It is crucial to keep the goldfish’s tank’s temperature at an optimal temperature to guarantee their survival. A condition of too high or too low temperature might be dangerous or even kill your goldfish.

Goldfish are cold-water fish, and their temperature demand is quite variable. They can cope in a temperature range between the ranges of 50-750F. They can also cope with a temperature that is slightly above or below this range.

Since goldfish are cold-water fish, they do not need a heater. In fact, it is best to keep them away from external heat sources and radiators. You can only consider using a heater if you need to raise the tank’s temperature to a suitable level.

Goldfish might also find it hard to cope with a drastic temperature change in the tank. Likewise, ensure the tank’s temperature stability, and if you need to make any change, it is best to make it gradual.

Do Goldfish Prefer Cold or Warm Water

Goldfish are generally more adaptable to cooler water temperatures and are considered cold-water fish. They can tolerate a wide range of temperatures, but they thrive in water temperatures between 65-75°F (18-24°C).

While they can survive in warmer water, temperatures above 80°F (27°C) can increase their metabolism, stress them, and potentially lead to health issues. Providing them with cooler water within their preferred range is ideal for their overall well-being and longevity.

Do Goldfish Need A Heater In Winter?

Keeping your goldfish during winter requires diligence. The question of goldfish needing a heater during winter or not is dependent on several factors.

If you are keeping your goldfish outdoors during winter, you might need to include a heater. The temperature outdoors during winter might drop below an appropriate point for goldfish in most areas.

On the contrary, common goldfish will not necessarily need a heater during winter if the tank is indoors. They can still cope with a temperature that is slightly below the normal range.

However, fancy goldfish will need a heater during winter because they are more vulnerable. They are usually prone to infections in temperatures below 60°F. The heater will help them stabilize the tank temperature and keep it optimal for the fish’s safety.

Can Goldfish Stay Outside In Winter?

The outdoor temperature during winter might become unfavorable for goldfish because it might drop below the freezing point. Therefore letting your goldfish stay outside during winter requires diligence and extreme care.

Goldfish can stay outside during winter if you include a heater in their tank. The heater will raise the tank temperature to a suitable level and stabilize it.

Alternatively, goldfish can survive outside during winter, significantly below freezing point by going into hibernation. However, goldfish in hibernation needs plenty of oxygen. Likewise, it is essential to keep ice off the tank or pond.

Can Cold Water Kill A Goldfish?

Goldfish are cold-water fish that can even survive in winter. They can cope in cold lakes, streams, and rivers. However, goldfish being cold-water fish do not mean that they can stay in frigid and freezing temperatures.

So, yes, cold can kill goldfish when it becomes very unbearable for them. When water temperature becomes too cold, their metabolism slows down, they stop eating, and become lethargic.

They will also become vulnerable to diseases and infections. Consequently, these conditions might force goldfish to go into hibernation or eventually die off.

Frequently Asked Questions 

Here are some frequently asked questions about adding a heater to a goldfish tank;

What happens if I overheat the tank?

Water temperature is one of the essential parameters in any fish tank, and goldfish is not an exception. Goldfish are cold-water fish, and overheating the tank will make the tank uncomfortable for them.

If you overheat the goldfish tank, the oxygen level will start to deplete. Low oxygen levels will make the fish suffer from general exhaustion and stress. It might weaken the immune system of goldfish and make them lose basic body functionality. So, it is safe to say overheating the tank can lead to the death of goldfish.

How long should I heat an aquarium?

Heating your aquarium to a suitable temperature is a good idea, but overheating the tank can be dangerous. You should heat your tank for about 24-48 hours. Ordinarily, an aquarium will reach the desired temperature within the first 24 hours, but the extra hours will ensure the temperature’s stability. You can continuously use a suitable aquarium thermometer to follow up the temperature in the tank to avoid overheating.


Goldfish is a loveable cold-water fish that can cope at varying temperatures. You won’t have to include a heater in the tank because they love cold water. A heater might only be necessary during winter outdoors or situations where you need to raise the tank’s temperature to a suitable temperature.



Hello, I'm Jason. I'm the guy behind I volunteer at my local fish shop and I created this site to offer tips and advice on the fish I care for.