Do Goldfish Need A Heater? We Heat Up The Reasons Behind This Unit!

Last Updated: July 13, 2022 by Flora Gibbins

Many goldfish owners are perplexed by this question: Do goldfish need a heater? Some owners respond yes, while others a stern no. 

Which is it? 

Well, both answers are correct. Goldfish thrive in cold waters. However, some goldfish species need an aquarium heater, while others don’t. 

This article discusses everything to do with goldfish and heaters. It explains the ideal temperature for goldfish, goldfish species that require a heater, and the effects of keeping goldfish at the wrong tank temperature. 

Read on. 

What Is The Ideal Water Temperature For Goldfish?

The ideal temperature range for goldfish depends on the species. 

Goldfish are considered cold-water fish that enjoy temperatures between 60 and 78 degrees Fahrenheit. 

Goldfish live more happily and healthily when their tank has a constant temperature, with or without a heater. If you observe the sudden rising or dipping temperatures, it would be best to get an aquarium heater. 

Factors That Determine Whether A Goldfish Needs A Heater

Two factors determine whether a goldfish tank needs a heater; goldfish breed and where it was raised. 

Breed

Some goldfish thrive in freezing, cold water, while others are comfortable in warmer water. Here are the varied ideal temperatures for goldfish species. 

Goldfish Species	Optimal Temperature (F)
Common Goldfish	60 to 75 degrees
Phoenix Goldfish	65 to 72 degrees
Fantail Goldfish	75 to 80 degrees
Orandas	65 to 72 degrees
Lionheads	60 to 75 degrees
Tamasaba	60 to 70 degrees
Bubble Eyes	70 to 80 degrees
Comet Goldfish	60 to 72 degrees
Shubunkin Goldfish	65 to 72 degrees
Japanese Wakin	60 to 78 degrees
Jikin Goldfish	65 to 78 degrees
Moor Goldfish	50 to 75 degrees

You can tell that different goldfish need different water temperatures from the table above. Goldfish live in cold waters in the wild. 

However, fancy goldfish need a warm temperature as they are more delicate.  

Phoenix goldfish, Fantail goldfish, Orandas, Bubble eyes, and lionheads are fancy goldfish species that need a heater.

Fantails thrive in temperatures between 75 and 80 degrees. Their lower temperature range is the higher range for some goldfish. This makes it necessary to add a tank heater to stabilize their temperature. 

Bubble eyes also need an aquarium heater to maintain the water temperature between 70 and 80 degrees. These fancy goldfish are quite sensitive to fluctuating temperature changes. Due to this, put them in a stable, heated tank, not a goldfish bowl. 

Orandas, too, get into shock when kept in colder temperatures. They need stable temperatures between 65 and 72 degrees. 

Condition They Were Raised

Goldfish are temperate fish. However, some goldfish are raised alongside other tropical fish like betta fish, tetras, guppies, and other livebearers. This means they are adapted to living in warm water conditions. 

If you bring such fish home, you must add a tank heater. Exposure to sudden temperature changes can cause these goldfish to go into shock, causing permanent damage or death.

If you prefer keeping goldfish in colder water, use a heater for the first days to replicate the conditions the fish were adapted to. Next, lower the tank temperature by bringing it down one degree every day. Doing so will prevent creating stress and health problems for your goldfish. 

How To Choose An Aquarium Heater

Now that we’ve established that some goldfish species need a heater let’s discuss how to find one. 

When choosing a heater, check its wattage. The general rule states a heater should have a minimum of 3 to 5 watts for every gallon of water. In addition, the heater should provide even heating to the tank. 

Most aquarium heaters feature suction cups to secure them against the glass or walls of the goldfish aquarium. 

The following are the types of heaters you will find: 

Hanging/Immersible Heater

These are the most common heaters. You hang them on your tank so that the heating element sits on the water surface. Hanging heaters provide basic heating but are not the best. 

Submersible Heaters

A submersible heater works by submerging it under the water line. It features a heating element enclosed in glass or tough plastic and heats the water flowing into the tank. A submersible heater is more efficient than an immersible heater. 

Filter Heater

This heater heats water as it passes through the filtration system. Some power filters and canister filters feature this heating mechanism. 

Substrate Heaters

Though uncommon and expensive, substrate heaters help maintain stable tank temperatures. These heaters evenly heat the substrate to keep the water warm. 

Do Goldfish Need A Heater In Outdoor Ponds During Winter?

Not really. Regular pond goldfish can thrive at low temperatures, even when the temperatures fall below 50 degrees during winter. 

When the temperature drops, the goldfish’s body temperature matches the pond’s temperature. 

The low temperatures cause the outdoor goldfish to have a low metabolism. They eat less and soon go into hibernation. During this time, stop feeding your goldfish as they are not digesting food. Moreover, the leftover food will only dirty the pond, creating water-quality problems. 

But what if the top of the outdoor pond freezes? Will your cold water fish require a heater? You will need a pond heater or a de-icer. A de-icer creates an open hole to allow gas exchange, which prevents your goldfish from suffocating and dying.

If you are worried about outdoor temperatures during winter, you can move your goldfish indoors. However, add a water heater to raise temperatures to a suitable range. Also, if you own fancy goldfish, add a heater during the cold months. 

What Water Temperature Is Too Cold For Goldfish?

Common goldfish are considered cold-water fish, but their water temperature should not drop below 50 degrees F. This is the extreme range for all indoor goldfish. Common goldfish and slim-bodied goldfish survive these cold temperatures, but they may stop eating and start hibernation. 

Also, some breeds cannot tolerate cold temperatures. The fancy goldfish, for instance, cannot survive in temperatures below 55 degrees. Low temperature creates health problems like blood clots for these fancy goldfish. 

Temperatures between 50 to 60 degrees will force your fish to become inactive. Since fish are coldblooded, their body temperature relies on their environment. When the temperatures get too cold, their metabolism slows down, and they hibernate. 

This is why you will notice your goldfish swimming at the bottom of the tank in a sluggish way. They will barely move until the temperatures start to rise. 

What Water Temperature Is Too Hot For Goldfish?

On the other hand, temperatures above 80 degrees are too hot for goldfish. This cold water species feels stressed in these conditions since warm water has less dissolved oxygen levels. Goldfish gasp for air at such high temperatures. 

To avoid this, place the goldfish aquarium away from direct sunlight and radiators.  Also, keep your goldfish in a large indoor aquarium to maximize oxygen absorption. Large tanks have a larger surface area that soaks more oxygen in. Alternatively, get an air pump to aerate the water. 

High temperatures also mean faster metabolism for your goldfish. They will not only become more active and grow faster but also eat more, excrete more, and cause higher bioload. 

This will increase ammonia, nitrates, and nitrites levels in the fish tank. These can lead to ammonia burns and infections if water quality is not maintained. 

What Happens When Temperatures Change Suddenly?

Extreme high and low temperatures are dangerous for goldfish, but so are sudden changes in temperature. The fish will go into temperature shock and kill the fish in minutes. If your goldfish do not die from shock, they may suffer permanent damage. 

Also, sudden temperature changes create respiratory problems. When the temperature rises fast, oxygen levels in the fish tank deplete fast, making it hard for the goldfish to breathe. 

Moreover, assume the temperature suddenly drops while your fish has food in their gut. Cold tank temperature lowers the metabolism rate, meaning the fish will not digest the food in time. This can prove fatal to your fish since the undigested food may start to rot in their gut. 

This is why you should always maintain a stable tank temperature whether you have a heater or not. 

Fun Fact: Read our article, How To Keep A Fish Tank Warm Without A Heater Using 6 Tips as a complementary side note to this post.

Here are more tips on caring for goldfish in this YouTube video:

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Frequently Asked Questions

What Are The Effects Of Sudden Temperature Changes On Goldfish? 

Sudden changes in temperatures make the fish prone to infections like fin rot and Ich. The changes also stress these cold-water fish. 

Do Goldfish Need A Heater During Winter?

It depends on the breed. Common goldfish can tolerate the cold winter months without a heater. However, fancy goldfish are more sensitive and need a heater to maintain warm conditions.

Fancy goldfish get stressed and develop a weakened immune system and infections when they do not have a heated tank. 

Do Fantail Goldfish Need A Heater?

Yes. They, like fancy goldfish, prefer water temperature above 60 degrees. A heater will help maintain stable temperatures during the day and night. 

How Can I Test Water Temperature In A Goldfish Tank?

An aquarium thermometer will check whether the tank temperature is at a suitable range for your cold water fish. You can add a floating, standing, or digital thermometer to the goldfish tank. 

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Conclusion

Goldfish do not necessarily need a filter. These cold-water fish can survive in temperatures between 60 and 78 degrees, with some surviving in colder temperatures below 50 degrees.

However, add a water heater to a fancy goldfish tank. These fish thrive in warmer conditions and are sensitive to cold water. 

As a goldfish owner, it is upon you to decide whether your goldfish need a heater or not.