Goldfish are much more complex than people are led to believe, and due to the abundance of different types of goldfish, it leads to many different requirements and preferences. Yes, goldfish do need heaters, but there are also specific species of goldfish that do not.
There are several different factors that determine the necessary water temperature for goldfish, and in this article we have listed what those factors are and what types of goldfish need a heater, and which species do not.
Factors that Influence Whether Your Goldfish Needs a Heater
There are several factors that go into whether or not your goldfish will need a heater in their fish tank or not. Let's dive in!
Specific Breeds of Goldfish
It may not be common knowledge, but there are a plethora of different goldfish species, ranging in size, shape, coloration, patterns, and behavior, which usually results in each different goldfish species having different requirements, and more specifically, temperature requirements.
All goldfish are considered temperate fish, meaning they do not 100% need a heater in order to survive, unlike most fish that come from the tropics. However, there are some types, such as the fancy goldfish that will simply not survive if sudden shifts in temperature occur due to them being interbred.
A heater is always recommended for fancy goldfish as it will keep things consistent and stable for them, creating the perfect environment for them to be healthy and thrive. If the water temperature of your tank reaches above 75℉ (24°C), you must reduce the temperature immediately as 68℉-72℉ (24°C-22°C) is their temperature range.
It really does depend on where you live too, if you reside in a place with extreme weather that changes constantly, a heater is certainly required for fancy goldfish as it provides stability. But if you live in a pretty warm home that remains at a fairly consistent temperature year round, then you should be fine.
Goldfish that Need a Heater
- Oranda goldfish
- Moors goldfish
- Telescope Eye goldfish
- Lionhead goldfish
- Bubble Eye goldfish
- Pom-Pon goldfish
- Pretty much all fancy goldfish breeds
Goldfish that do not Need a Heater
- Comet goldfish
- Shubunkin goldfish
- Common/Feeder goldfish
- Japanese Wakin goldfish
- Other non-fancy breeds
Captivity Water Conditions
Fancy goldfish, such as the Oranda goldfish, have been bred in aquarium conditions for the past few decades, which makes them well acclimatized to tropical warm waters.
If you are aware of your goldfish's captivity water conditions and know it has been raised in a warm temperature and water conditions, you should certainly replicate this in your own aquarium. Or alternatively, reduce the temperature by a degree per day to steadily acclimate them to your proposed temperature.
Keeping fancy goldfish below 60℉ (15.5°C) will certainly be detrimental for them, we would certainly recommend avoiding temperatures below 60℉, especially for the larger adults that have never been exposed to temperatures that low.
Pond Goldfish and Heaters
Typically, pond goldfish are pretty different in their requirements than regular aquarium goldfish. This isn't to say that they won't need heaters due to their hardier nature. The majority of outdoor ponds are too big for heaters, except for container ponds, which means that your goldfish must be able to tolerate outdoor temperatures.
Most pond aquarium owners will bring their pond goldfish indoors during the winter months if the pond is particularly shallow and susceptible to freezing. If you reside in a temperate country or state without too many drastic fluctuations in temperature, you won't need to bring your goldfish indoors during the winter, as long as the pond is 3 to 4 feet deep (about 90-120cm).
Outdoor pond goldfish and Koi are temperate fish originating from both China and Japan, which aren't exactly known for their warm winters, so, as long as your pond has a hole in the ice for oxygen-carbon dioxide gas exchange, your fish will easily survive the winter months. The equipment to create this ice hole is a pond heater, which is often referred to as a de-icer.
Temperature Swings - What Will Happen to Your Goldfish?
So, what will happen if your goldfish gets too hot or too cold? Well, the water temperature affects pretty much all fish in very extreme ways, with most fish being cold-blooded. Being cold-blooded means that your body temperature is completely controlled by the environment it is in. As the surrounding temperatures decrease, so will your fish's metabolism.
When temperatures decrease to as low as 40℉-42℉ (4°C-5°C) your goldfish will enter something called torpor (hibernation). This results in them continuing to breathe but not really moving, resting at the bottom of the pond or tank until the spring months arrive.
Rising temperatures will have virtually the opposite effect, and surpassing 75℉ (24°C+) can be very harmful to your goldfish. So, the hotter the environment for your goldfish, the faster their metabolism will work, leading to them eating more, pooping more, and growing much quicker.
As a hobbyist, it is important to know what the negative effects of overfeeding your fish are, as well as warm conditions being the perfect breeding ground for bacteria and other harmful things. If your aquarium is hotter than it should be, then you should certainly add a filter to your goldfish tank.
In conclusion, the majority of goldfish do not need heaters, but there are some circumstances that would certainly involve you needing to purchase a heater for your goldfish aquarium. Many factors play a part in this, and we have covered them all here. It is important to note that the weather plays the biggest factor too in whether or not you need a pond heater.
Despite most goldfish not requiring heaters in order to survive, remember that if you can get one for your tank it will certainly help with stability and consistency, which, in return, will benefit your goldfish tremendously.