Do Goldfish Need A Heater? What You Should Know For Healthy Fish

Many goldfish owners are unsure about the equipment required including whether they should put a heater in their aquarium. The fact that goldfish can endure a wide range of temperatures confuses many. So, do goldfish need a heater?

The cold water habitats of streams, rivers, and lakes are ideal for goldfish to survive and thrive in the wild. Even though goldfish are considered coldwater fish, and some breeds can survive in temperatures as low as 32 degrees Fahrenheit, that does not mean they should be kept in frigid temperatures.

Do Goldfish Require A Heater? It Depends

Common, Comet, Shubunkin, Wakin, Jikin, and Watonai are six goldfish breeds that do not necessarily require a heater, but it can be beneficial to include one in their aquariums. A temperature in the room of seventy degrees Fahrenheit is the perfect water temperature for these goldfish breeds, keeping in mind that if the temperature in the room goes up past 90 degrees, the water temperature will rise too.

Ideally, these goldfish’s water temperature should be between 65 and 72 degrees Fahrenheit. Including a heater gives you more control and allows you to monitor and adjust the temperature more precisely. 

As a side note, acclimation is far more critical to your goldfish than the water temperature in and of itself. Temperature extremes can be dangerous, but these hardy goldfish tolerate a wide temperature range if adequately acclimated. A rapid change in the water temperature can lead to shock. 

Do Goldfish Need A Heater | colorful goldfish swimming in aquarium

What Happens To Goldfish In Water That Is Too Cold?

Goldfish will become lethargic and may eat less at low temperatures (below 60 degrees) because this is a sign of impending winter in the wild. In captivity, however, the fish are more likely to starve to death if temperatures remain at this level and never drop to torpor levels (lower than 50 degrees).

Once the temperature goes below 50 degrees, after a steady period of dropping, your goldfish will hover at the bottom of your aquarium and be in a state of significantly reduced metabolic activity. While goldfish can survive in the torpor state for a few months, unhealthy or underweight goldfish may die if the period is too long. 

What Is The Maximum Water Temperature For A Goldfish?

Eighty degrees is the maximum temperature a goldfish can handle. Anything above 80 will cause the goldfish to overheat and become sluggish. A water temperature that is too hot (or too cold) will significantly lower the water’s oxygen levels.

If you find your goldfish often swimming near the top of your aquarium and gulping for air, the water is too hot, and they aren’t getting enough oxygen. You can combat this by adding more filters and air stones (increasing water circulation). Additionally, because oxygen from the air enters the tank water at the surface, think about using a tank with a sizable surface area.

It is best to place your goldfish aquarium in a cool, draft-free area of your house and out of direct sunlight. Water heaters are much more accessible and affordable than water cooling systems.

Are There Any Benefits To Keeping Goldfish In Warm Water?

Your goldfish will benefit significantly from being kept in warmer water (72 to 80 degrees). For example, they will have better immune and digestive systems, and you’ll probably notice that they swim and grow more quickly.

Fancy goldfish are not as resilient as the six goldfish breeds mentioned earlier, so if you intend on keeping fancy goldfish, it is recommended to include a heater in their aquarium. Fancy goldfish are more prone to diseases and infections in temperatures below 70 degrees. Fancy goldfish also have trouble digesting their food in cooler water which is the leading cause of swim bladder problems. 

The warmer water will increase their metabolism, and therefore, their immune systems will get stronger. Increased metabolism will help them digest their food faster too. However, it would be ideal if you kept in mind that since their metabolism is boosted, there will be more waste (ammonia), so you’ll need to do more frequent water changes and ensure you have enough filters (as many as possible).


Whether or not goldfish require a heater ultimately depends on the type of goldfish in your tank. However, there are an array of benefits to keeping your goldfish in warm water regardless, including a stronger immune system and happier fish.

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