Do Goldfish Need Heater?

The goldfish is a very common pet in aquariums, and it has been selectively bred over the years to result in fancy species of diverse colors, fin types, and body shapes.

It is indigenous to eastern, where it inhabits different freshwater habitats, from tropical to temperate conditions.

The goldfish is, therefore, quite hardy, which encourages its popularity among aquarists.

When it comes to temperature, however, some ranges will be better for your goldfish than others.

Do Goldfish Need Heater?

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Do Goldfish Need Heater?

Which Temperature is Ideal for Goldfish?

Most common goldfish are impressively hardy, and they can even live in water that is almost freezing. Scientists in one research maintained temperatures of 39 °F (4 °C) to evaluate changes in the metabolism of goldfish. The fish survived without any adverse effects.

It is recommended to keep goldfish between 60 and 70 °F (16-21 °C), although this is mostly suitable for fancy goldfish. If you have fancy goldfish therefore, you will need a heater to ensure that temperatures do not fall below the recommended range. The heater will especially be necessary if your aquarium is not positioned in an insulated or climate-controlled area.

Which Goldfish Need a Heater?

While the common goldfish will survive in cold water, the fancy species will not survive in equally low temperatures. The latter will likely die if temperatures fall below 60 °F (16 °C).

You will need aquarium heaters for many kinds of fancy goldfish, including Butterfly, Tosakin, Froghead, and Celestial Eye. For the Japanese Tamasaba goldfish, temperatures should be between 60 to 70 °F.

Some species like the fantail goldfish will need higher temperatures between 75 to 80 °F (24 – 27 °C). Keeping fancy goldfish in low temperatures will trigger immune implications. The Lionhead goldfish, for example, will be vulnerable in temperatures above 75 °F and lower than 60 °F.

Other kinds of fancy goldfish are extremely sensitive to temperature changes. The Bubble Eyes cannot be put in a fishbowl because it needs temperatures between 70 to 80 °F.

Goldfish Breeding Temperature

The ideal temperature for goldfish will depend on whether you intend to breed your pets. If you are planning to breed your fish, you will need to recreate similar temperature conditions as those of the wild habitat of the goldfish. The species spawns in the course of Spring when water becomes warm after winter.

To encourage your pets to lay eggs, you will need to reduce your aquarium’s temperature during winter to around 54 °F. Raise these conditions by 2 to 3 °F daily until it gets to between 68 °F to 74  °F.

Caring for Goldfish Over Winter

Caring for Goldfish Over Winter

Caring for Goldfish Over Winter

Your goldfish will demand more attention over winter because of the cold temperatures. You may need to shift your aquarium to a cool area if your home is very warm. You can set up the tank in the basement or any other region that is cooler than most of the other rooms. The health of goldfish will be compromised in temperatures above 75 °F.

If temperatures drop to below 60 °F, on the other hand, your pets may enter a period of hibernation. If you have kept them in a pond, they will probably occupy the bottom and stop feeding. This change will come about when temperatures fall into the mid to low 50s. Before this drop, you should begin overfeeding your pets.

As soon as temperatures fall to below 50 °F, cut down on the amount of food you give the goldfish. Give them food that is low in protein during this time to reduce waste production. Goldfish can go without food for quite some time. It is critical to maintain good water quality during the time that your goldfish are in hibernation. Goldfish can typically survive a few months of dormancy. The temperatures should, however, drop gradually to enable the pet to adapt.

The other threat to your goldfish during winter is reduced oxygen levels. These levels normally drop in colder temperatures, especially if there is ice present in the pond. Goldfish demand sufficient oxygen and they will suffocate in habitats with low concentrations of the gas. You can add an air stone in the pond, although it should fit the pond size.

The fish will survive in the event that the top layer of the pond ices over. A small hole will ensure that there is sufficient oxygen getting to the goldfish. Ensure that the pond does not freeze completely by installing a pond de-icer.

How to Control Your Aquarium’s Temperature

Depending on the kind of goldfish you are rearing, you may need a heater to maintain temperatures at a suitable range.

A quality heater will eliminate the costs of replacing the device, which can be unnecessary and expensive. The gadgets come in various kinds, and the choice will depend on cost and preference. These varieties include:

  • Hanging Heaters – Beginner aquarists commonly buy hanging heaters, which are mostly packaged with the starter kit. The heater will hang over the tank’s top, while the heating device sits in the water. You will need to create a hole at the top of your tank to accommodate the heater’s design. It will provide basic heating, but it is not very efficient.
  • Submersible Heaters – Submersible heaters are positioned under the water. It sits close to the filter’s inlet so that it easily heats the water that is getting in the tank. Its heating element is often encased in toughened plastic tube or glass, although glass can break in high temperatures. Submersible heaters are conveniently fitted with LED lights at the top to indicate when it is on.

While heaters will work for an indoor aquarium, they are not necessary in an outdoor pond. Goldfish are quite hardy, and they will survive through low temperatures. Common goldfish will mostly hibernate through the winter, but they will be active again once the temperatures rise. If you notice the top of the pond icing over, create a hole to ensure a consistent circulation of oxygen.

Once you settle on a heater, the next step is figuring out where to place it. The best area is where water flows in and out because water will be evenly heated. It is important for the whole tank to have a constant temperature. If you have a big setup, you can place two heaters on opposite sides.

When it comes to installation, most heaters will be equipped with suction cups to anchor them to the tank’s walls. Let the heater settle for about 20 minutes to be sure that the casing can handle temperature changes.

Activate the heater and adjust to the most suitable range. Adjustments can be made after six hours to ensure the temperature does not deviate from the intended average. You can give the heater a day to determine its effectiveness.

How Can I Test the Temperature?

A thermometer will come in handy in testing the actual temperature of your aquarium.

A good model will be very accurate and have a suitable range. You can get one with a range between 50 °F to 104 °F.

There are several thermometer types, including the digital aquarium thermometer. It comes with a digital display that is easy to read. The temperature will mostly be both in ºC and ºF. You can either get one powered by batteries or the kind with an electrical plug. Some models will have an alarm feature so that you get notified when the temperature falls below or above the set limit.

Floating thermometers are more common, and you only need to submerge the whole gadget. It can be challenging to decipher the print scale, although most brands will have different colors to mark the protected zone.

A big aquarium will need multiple of these thermometers, which can be inconvenient. Since they are made with glass, these thermometers are quite vulnerable to breaking. They can either be weighted at the base, magnetic, or fitted with suction cups for anchorage.

Stick-on thermometers are placed outside the tank, and their readings can be impacted by the room’s temperature. Heaters and even direct sunlight can also influence the readings of these thermometers.

When Do Goldfish Need a Change of Temperature?

When rearing goldfish, you may need to adjust the temperature for short periods.

One such time is during breeding since the reproductive capabilities of the fish are influenced by the environment. In the wild, it will produce more androgen, which is the reproductive hormone, during Spring.

The hormone is produced in fewer amounts when it is cold. This pattern is evolutionary to ensure that larvae survive in high populations in warm conditions. You will, therefore, have to mimic these temperature changes to encourage your pets to breed.

Some goldfish diseases can be addressed with temperature changes. If your pets become victim to parasites, you can raise the temperature to about 30ºC for ten days. If you are treating White Spot, raising temperatures will reduce life the parasite’s life expectancy. Your goldfish will recover quicker and respond better to treatment.


Goldfish are loved by aquarists primarily because of their hardiness. They will respond to a variety of conditions, including a wide range of temperatures. Fancy goldfish are however sensitive to water temperatures, and they can be vulnerable to even slight changes in their environment

The fancy goldfish need a temperature between 60 to 70ºF. During cold winter temperatures, you will be surprised at the resilience of your common goldfish, as they will survive even in outdoor ponds as long as they get oxygen. To raise temperatures, rely on a quality heater and a good thermometer to test the conditions.

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