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Although traditionally thought of as cold-water fish, goldfish can live happily in warm waters. In fact, many of the ‘fancy’ strains of goldfish do better when kept at temperatures in the low to mid-’70s. The higher temperature is better for their metabolism, leading to stronger, healthier fish.
Traditionally thought of as cold-water fish, goldfish can live happily in warm waters. In fact, many of the ‘fancy’ strains of goldfish do better when kept at temperatures in the low to mid-70s
What Is The Ideal Temperature For A Goldfish Tank
Goldfish have been kept as pets for centuries. Over that time, the myth has developed that goldfish are ‘cold water’ fish. Goldfish are often kept in unheated aquariums in our homes, and for the most part, they do really well.
Water temperature has a direct effect on a fish’s metabolism. That is to say, the temperature of the water affects how quickly food eaten by the goldfish is broken down by the fish’s digestive system.
In warmer water, the fish can break down the food quicker and convert that food to muscle, fat, and body cells quicker. In colder water, the process takes a lot longer. For more information on what to feed goldfish, why not read my article Best Food For Goldfish.
The optimum temperature for the ‘fancy’ strains of goldfish, such as Orandas, Fantails, and Ranchus is 70 – 76 degF. For non-fancy strains such as common goldfish, comets, and shubunkins a water temperature of 68 – 72 deg f is best.
How Warm Can Goldfish Go?
The warmer the water gets, the quicker the fish’s metabolism will work. The faster the metabolism works, the more food the fish will need to consume. Once temperatures start to get too high, the goldfish will become stressed.
This stress will lead to a weakening of their immune system. Goldfish kept in water that gets much hotter than 76 deg F will quickly show signs of illness. Ich (whitespot) is an early indicator of a fish’s poor health (see my article Why Does My Goldfish Have White Spots?). Bacterial infections will also take advantage of your goldfish’s weakened system.
If you live in a hot climate, natural air temperature can raise your goldfish aquarium above 76 deg F. At this point, you should consider ways to cool down the aquarium water.
Having a fan blowing across the open tank top will reduce the temperature via evaporative cooling. Floating small bags of ice can also help reduce the aquarium temperature.
Whatever way you try to cool an aquarium, take care not to reduce the temperature too much or too quickly, as either one can lead to the death of your fish.
Is Cold Water Bad For Goldfish
Coldwater in itself isn’t bad for your goldfish, the problem is, as discussed above, the colder the water, the slower the fish’s metabolism will work. When we keep koi in outdoor ponds, their metabolism will slow right down over winter.
They won’t feed at all. They go into an almost hibernation-like state. They have evolved to do this. The fancy goldfish we keep in our aquariums haven’t evolved along the same lines.
Once the aquarium water starts to go below 60 deg F, your goldfish will become lethargic and may stop eating. Any food they do eat may take a long time to break down in their digestive systems.
As when temperatures are too high, this will lead to stress and your goldfish may become susceptible to infections and diseases. Their bodies will be less able to fight off any bacteria which resides in their aquarium.
Can Goldfish Live With Tropical Fish
Can goldfish live with tropical fish, yes, should they, well that depends. We have had great success keeping goldfish with their ‘tropical’ cousins, but you have to select their tank mates carefully.
Fancy goldfish are slow swimmers. If you keep them with fast swimming species like danios or some of the rasboras, the goldfish will never get to see any of the food. You would have to continue to feed the aquarium until the fastest swimming tanks mates have had their fill and the slower goldfish can have a turn.
Common goldfish on the other hand are very fast swimmers. Keep them in a tank with a slower swimming species like gouramis or some of the dwarf cichlids and the goldfish will dominate the food and the slower swimmers will miss out.
Fancy goldfish often have fantastic flowing fins. Some of the nippier tropical species, like many members of the Barb family, will nip at the goldfish’s fins, creating stress and increasing the chances of bacterial infections setting in.
I currently keep 2 large Oranda goldfish with a group of Zebra Danios. The Danios are too fast for the Orandas to catch and eat them, so the setup works well. I do however have to be careful that the Danios don’t dominate the food.
All goldfish grow fairly large, and as the old adage goes, ‘If a fish can fit in their mouths, one day, they will go there!’. If you keep goldfish with small species of fish, your goldfish may see them as prey items. A couple of large goldfish will make short work of a school on neon tetras!
How Can We Best Heat A Goldfish Tank?
Unless you are running a large fish room with multiple tanks, a submersible heater is best for heating an aquarium. I have had great success with the LED heaters from Fluval. They are easy to adjust and have a digital display, which really allows you to fine-tune the temperature of the water.
What Size Tank Do Goldfish Need?
This is possibly one of the most hotly debated topics on the internet. In our opinion, a 30 gallon plus is ok for a couple of fancy goldfish, providing you are happy to keep up with the water changes.
A 40 gallon would be better still. Traditionally of course goldfish were kept in bowls, but a bowl simply isn’t big enough. The water will quickly become polluted from the fish waste and the goldfish will have a short, miserable life.
In Conclusion
Get the temperature of the aquarium right, and your goldfish will grow strong and healthy. If the water is too hot or too cold, your goldfish may be susceptible to diseases or bacterial infections. Aim for a temperature in the low to mid 70’s. Heat your tank with a reliable aquarium heater and, if you wish to keep your goldfish with some of their brightly colored tropical cousins, choose tankmates wisely.
Goldfish are great fun to keep and, if you get the conditions right, will reward you with 20 years or more of fish-keeping pleasure.
