Goldfish Temperature: How Hot Or Cold Is Needed By Your Pet?

Goldfish Temperature
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Last Updated: July 13, 2022 by Flora Gibbins

The ideal tank water temperature for goldfish has raised numerous discussions among aquarists. Some argue that goldfish need warm water temperatures like tropical fish, while others recommend cooler temperatures. 

As a classic example…

Goldfish thrive in different water temperatures. This means they can live in cooler and warm water. 

This article will discuss in length the optimal water temperatures for goldfish. We will also discuss why you should always maintain a stable water temperature.

The Perfect Tank Temperature For Goldfish

Goldfish Temperature

Goldfish live in cool rivers, streams, and lakes in the wild, which is why they are regarded as cold-water fish. The appropriate temperature for keeping goldfish should be between 62 to 74 degrees Fahrenheit (16 to 23 C).  

This temperature range works for all goldfish breeds as it contains sufficient oxygen levels, promotes growth, and does not stress your fish. However, since there are numerous goldfish species, you must maintain the ideal water temperature for your specific pet goldfish. 

Slim-bodied goldfish are hardy fish that can tolerate freezing temperatures. The Comet goldfish and common goldfish can withstand winter temperatures in outdoor ponds without a heater as long as you maintain water quality and sufficient dissolved oxygen levels. 

The fancy goldfish, however, are quite sensitive and cannot withstand cold water. 

The Bubble Eye and Orandas are more prone to stress and infections if they are not kept in a heated tank in the cold months.  

Both the slim-bodied goldfish and fancy goldfish require you to maintain a constant temperature. In the wild, goldfish swim to waters with their desired temperature. But since they are in captivity, you should always keep their tank temperature in the optimal range.

Goldfish Water Temperature In Winter

Water Temperature In Winter

Winter is characterized by freezing temperatures. However, common goldfish can live in these conditions in outdoor ponds. However, you must ensure that the water does not freeze completely and that the pond is aerated. 

When the temperatures drop below 60 degrees, provide cold water goldfish food. Also, limit their daily intake since their metabolism slows down at these temperatures. Stop feeding once the temperatures hit 48 degrees F as their bodies cannot digest food. 

Any food you add to the pond during this time will only cause health problems for your fish. Furthermore, when this food decomposes, it will cause an ammonia spike, harming your fish. 

If your pond freezes at the top, facilitate gas exchange by maintaining an open hole in the ice. You could use an aerator or de-icer. You do not want your goldfish to freeze to death or suffocate. 

Fun Fact: Read more about the article “Do Goldfish Need A Heater? We Heat Up The Reasons Behind This Unit!” to complement the aforementioned sub-topic.

Goldfish Water Temperature In Summer

Water Temperature In Summer

In the summer, the water temperatures in the goldfish tank should not exceed 86 degrees F. Your fish may prefer to stay at the bottom of the aquarium to enjoy cooler water during summer. Additionally, this is where they will get more dissolved oxygen. 

 If you observe that the goldfish tank has higher temperatures, do the following to reduce them:

  • Removing the top lid
  • Placing a fan close to the aquarium
  • Close the blinds or curtains to limit direct sunlight
  • Add ice packs

Remember, goldfish are sensitive to sudden temperature changes. So, lower their temperature gradually. 

What Water Temperature Is Too Cold For A Goldfish?

Water temperatures below 55 degrees F are considered too cold for goldfish. But as cold-water fish, slim-bodied goldfish can tolerate freezing water with temperatures as low as 32 degrees F. They go into torpor at these temperatures. 

However, do not subject fancy goldfish to water temperatures below 60 degrees as they have a weaker immune system. 

What Water Temperature Is Too Hot For A Goldfish?

Temperatures above 80 degrees F are too hot for goldfish. This could be due to overheating the tank or placing it near radiators or in direct sunlight. Goldfish have trouble breathing at high temperatures since hot water has less oxygen. They also become stressed, which opens doors for infections. 

How Water Temperature Affects Goldfish

Unknown to many aquarists, the aquarium temperature affects goldfish behavior and overall health. Here are three ways the temperature affects goldfish. 

Affects Simple And Complex Body Functions

Goldfish are exothermic, meaning their body temperature relies on their environment. Their overall body functions depend on the temperature of their surrounding water. If the tank water is warm, these fish absorb this energy and release it by being more active. 

There is a huge behavioral difference between goldfish living in temperatures of 50 to 60 degrees F and those in 60 to 70 degrees F. The fish in cold temperatures appear less active than those in warmer water. 

Fancy goldfish would become unresponsive if kept at temperatures as low as 55 degrees. 

Also, water temperature affects metabolic processes like respiration, digestion, and immunity. Temperatures between 60 to 70 degrees F promote better immunity through more oxygen absorption rate and better digestion. 

Affects Water Properties

Temperature changes also affect the properties of the tank water. For starters, warmer water has less oxygen compared to cold water. So, if you keep your goldfish at higher temperatures, they will experience breathing difficulties.  

Moreover, the toxicity of ammonia doubles with rising temperatures. Ammonia levels that could be safe for your goldfish at 50 degrees F can prove fatal at 70 degrees. 

Impacts Immunity

Disease-causing parasites, fungal or bacterial, thrive in warmer temperatures. This means that your goldfish are more prone to diseases while their tank temperature is on the higher end. 

When Is It Okay To Change Goldfish Water Temperature? 

There are two times when changing the optimal temperature of goldfish is acceptable, but for short periods. You can raise or lower the temperature to treat goldfish diseases or encourage breeding. 

Here is when it’s okay to change goldfish water temperature:

When Treating Goldfish Diseases

Did you know you can treat some parasitic infections through temperature changes? Well, warmer temperatures reduce the lifespan of some parasites, thereby speeding up the healing process of your sick goldfish. 

For instance, you can treat white spots by keeping your fish in warmer water for ten days. However, some parasitic diseases require you to include medication to kill off these parasites. 

Other fish diseases are treated by lowering the water temperature. Herpes virus, for instance, has no cure. But it can be managed by lowering the tank water temperature. The recommended temperature for keeping goldfish with this virus is 50 to 59 degrees. 

When Encouraging Breeding

Goldfish, like other fish, have a seasoned breeding pattern. They spawn in spring temperatures while in their natural habitat.

If you want to breed your goldfish, lower the temperature gradually to 54 degrees to encourage the females to lay eggs. Next, encourage the males to fertilize the eggs by gradually raising the temperature to 68-74 degrees F. 

Watch this YouTube video on the benefits of creating warmer spots in your aquarium for your goldfish: 

Why Should You Acclimate Your Fish?

Acclimation is the process of adapting your goldfish to a new environment. This is in terms of water temperature, pH, and chemistry

If you introduce your goldfish to sudden, extreme temperatures, then they will get stressed or go into shock. 

Symptoms of shock include:

  • Rapid breathing
  • Erratic swimming
  • Lethargy
  • Gulping at the water surface
  • Overproduction of slime

If you have new fish, float the package bag into the tank so they can slowly adjust their body temperature to the tank temperature. Also, when you perform a water change, ensure the temperature range of the freshwater is similar to the aquarium water. Use a water conditioner to remove any chemicals.

Do Goldfish Need A Heater?

In all honesty, it depends on the goldfish breed. Smaller fancy goldfish need a water heater to maintain an ideal temperature of between 72 to 78 degrees. In colder temperatures, they are susceptible to bloat, constipation, and swim bladder disorder. 

On the other hand, slim-bodied goldfish do not need a heater. They can adapt to freezing conditions without any health complications, provided they have enough air to breathe. 

How To Maintain Ideal Temperature In Goldfish Tank

At this point, you acknowledge that maintaining the desired temperature will keep your fish healthy. You can achieve this by using a water thermometer. A submersible thermometer or floating thermometer can help you take accurate readings.

We recommend a floating thermometer for large goldfish tanks and stick-on thermometers for small fish tanks. 


Frequently Asked Questions

What Should I Do If My Goldfish Tank Has Reduced Oxygen Levels?

If your fish are gulping for air, agitate the water surface to promote oxygen absorption or perform a partial water change. 

What Temperature Should A Goldfish Bowl Be?

We caution against keeping goldfish in a bowl since it has limited space and the temperatures can change drastically. A good rule for housing goldfish is to keep goldfish in a 10-gallon tank. 


Conclusion

Goldfish prefer cooler waters, between 62 and 74 degrees F. They can also tolerate temperatures higher or lower than this range. The key to keeping goldfish happy and healthy is to maintain a constant temperature. 

These fish get stressed and prone to fish diseases when the water temperature is not stable. We recommend you invest in a quality thermometer to ensure the temperature in the fish tank is ideal. If you own fancy goldfish, invest in an aquarium heater too.

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