Goldfish Water Temperature Guide – What is the Range for Goldfish?

You’ve probably heard that goldfish are coldwater fish, but is that true and what exactly does it mean?

Goldfish are often misunderstood pets, which leads to them merely surviving in subpar water conditions, rather than thriving. And one of the most important aspects of their environment is temperature.

Shubunkin colored fancy goldfish in a heavily planted tank

We’ve put together this article on goldfish water temperature to teach you everything you need to know on the topic, so you can get things right.

From why you need temperature control, to the correct temp to aim for, and how you can get there and maintain it in your aquarium.

What’s the Correct Water Temperature for Goldfish?

The first thing you need to know is what the correct water temperature for goldfish is. This isn’t as simple an answer as it sounds, however, as they can live at quite a range of temperatures, depending on the variety and what they’re used to.

For an average indoor goldfish (fancy or common), the ideal is somewhere between 72 and 75 degrees Fahrenheit, or 22 to 24 Celsius.

If you want to breed your goldfish, however, the water temperature should be closer to 68 degrees Fahrenheit.

Some fish are kept in ponds, and they have to withstand much cooler temperatures. Fish kept in colder water do move slower, however, and it’s likely that it may affect some of their metabolic functions. When it gets too cold, they even hibernate.

So, essentially, if you’re keeping your goldfish indoors, the optimal and recommended temperature is between 72 and 75 Fahrenheit, but they can be kept at lower, and slightly higher, temperatures.

What’s more important is maintaining a relatively consistent temperature, as a quick changes can shock your fish and even cause death.

Why do Goldfish Need Water of a Particular Temperature Range?

Goldfish can survive in a wide range of temperatures, so why should you keep their water in the 72 to 75 Fahrenheit range? Well, there’s a difference between just surviving and genuinely thriving, and you want your fish to do the latter.

You’ll notice that goldfish swim a lot faster when their water is warmer. Those kept in too-cold water are sluggish and, when the temperature drops too low, it may cause problems with various metabolic functions.

Common goldfish are more tolerant of cold water than fancy varieties, but that still doesn’t mean it’s ideal.

How do You Monitor the Temperature of Your Goldfish Tank?

Now you know the ideal temperature for your goldfish tank, you need to know how to check and monitor it.

The only way to be sure is by using an aquarium thermometer. You’ll find various types of aquarium thermometers available, each with their pros and cons.

While digital thermometers are often the most accurate and easiest to read, even a simple stick-on model will suffice for a goldfish tank if you’re on a budget, since you don’t have to control the water temperature for a goldfish to a fraction of a degree.

How do You Control Your Goldfish Water Temperature?

So, how do you make sure the water in your goldfish’s tank is kept at the correct temperature? Well, the easiest and most foolproof way is to use an aquarium heater.

Many goldfish-keepers don’t believe you really need an aquarium heater in a coldwater tank, assuming you’re keeping it indoors in an area that’s heated in the winter.

While there is some truth in this – the water temperature is unlikely to fall out of a safe range for your fish – it will still fluctuate, depending on the ambient temperature of the room. As we’ve learned above, fluctuations aren’t good for goldfish, so it’s best to keep their tank’s temperature stable by using a heater.

When looking for an aquarium heater, be sure to check whether you can adjust its output. Some models are set to a single temperature, which is generally designed for tropical tanks, so would heat the water too high.

You can also help control the temperature in your by avoiding external factors that can cause fluctuations—more on that below.

What Can Cause Fluctuations in Water Temperature?

Even if you have an aquarium heater, some external factors can cause fluctuations in your goldfish’s water temperature.

Factors that could potentially cool down the water aren’t as serious, as long as your aquarium heater is functioning properly, because the heater will warm the water back up to the correct range. That said, it’s still worth avoiding causes of fluctuations in temp where possible.

Also, if the water gets too hot, options for cooling down water are far more limited so you want to avoid this whenever possible.

These are some of the most common factors that can cause fluctuations in water temperature:

  • Radiators or other heaters. Placing your aquarium too close to a radiator or space heater can cause temperatures to rise.
  • Ambient room temperature. Whatever the temperature is in the room where you keep your goldfish will affect the water in the tank. Make sure you heat the room in winter (although the aquarium heater can pick up any slack) and consider turning on your air conditioning or using fans if it gets too hot in summer.
  • Drafts or direct sunlight. It’s not a good idea to place your goldfish tank too close to a window, or in direct sunlight. When it gets hot out, the water in the tank is likely to overheat, if it’s placed too close to a window, and in colder months, it can get cold or drafty.

What Can We Take Away About Water Temperature for Goldfish?

Goldfish care isn’t as simple as many people think, but now you know more about the correct water temperature for your goldfish, you can make sure you’re getting it right and doing best for them.

Although an aquarium heater isn’t a must-have for a coldwater tank, we’d certainly recommend using one to help maintain a consistent temperature, which will provide a more pleasant and comfortable environment for your fish.

Happy fish keeping!

Wendy Kathryn

Hi, I'm Wendy, the owner and creator of this website, an experienced fish keeper and avid student of the art since 2010. My aim is to help beginners avoid the many possible mistakes when getting started in this wonderful hobby.