If you have perhaps accidentally let your goldfish pond freeze solid during the wintertime, you may be wondering if your goldfish can survive. The simple answer is no. Unfortunately, goldfish cannot survive being frozen for long periods, with the potential exception of a few seconds. Although this cannot be guaranteed. Goldfish are not able to come back to life after being truly frozen, regardless of the few stories you have heard (which have a misleading backstory if it is true).
Goldfish are cold-water fish by nature and can survive in a variety of temperatures within your pond or aquarium. There are certain limits to the temperature a goldfish can survive in and that is at below zero and frozen for more than 5 minutes. The goldfish will ultimately die due to shock.
If you have rescued your frozen goldfish, but they are frozen stiff, you will not be able to revive them.
Table of contents
Why Can Goldfish Not Survive Being Frozen?
Well, it is all brought down to your goldfish’s biological make-up of cells. A goldfish does poorly in sub-zero temperatures even if it is still alive. A goldfish should have access to a stable temperature that does not fluctuate out of their danger zones.
A goldfish will appreciate a temperature range between 18ºC to 24ºC. Although goldfish are resilient enough to survive temperatures outside this range, it does not mean it is recommended and can be harmful.
Goldfish will lose gill and mouth mobility (they puff their gills in and out with their mouth) and in turn, no oxygen can enter their bloodstream. It will lead to suffocation and painful ruptures in the body if they are thawed out after.
Goldfish Cell Biology and Cold Endurance
Goldfish have delicate membranes that will rupture when they expand. It happens when tiny ice crystals form on them, which is usually a few minutes after being exposed to sub-zero temperatures. It is the main cause of death after they have been frozen and is a painful process that is slightly numb due to the goldfish’s body going into a survival tactic and slowing their metabolism down.
Goldfish are adapted to survive in temperatures as low as 5ºC. Their body goes into winter sleep, they will not eat and remain inactive. If they are exposed to this temperature for a long time, they will slowly die.
With all the new goldfish varieties being produced, especially the fancy varieties, their adaptation to this survival method lessons. Fancy goldfish do poorly under 15ºC as their genetic digestibility will decrease more than a hardy common or comet goldfish.
How Long Can Goldfish Be Frozen for?
A goldfish exposed to freezing temperatures can survive for a few hours till its body completely freezes over. Once they are stiff and covered in specs of ice they have passed away. Reviving them by warming them up will cause them to decompose rapidly and produce a horrid smell.
If the goldfish are in a pond that has frozen over, they will most likely survive for a while until their body takes a toll. Fancy goldfish are not able to handle frozen over ponds. Trying to ensure the pond does not freeze over is important. There is no guarantee a goldfish will survive.
It is not a good idea to attempt to see how long a goldfish can survive being frozen. As interesting as the experiments regarding this topic have been, there is enough evidence to foresee the outcome than for you to test it out.
How to Revive a Goldfish in Temperature Shock
If your goldfish has been exposed to extremely cold temperatures but is not yet frozen, you will need to place them in a container of their tank water. Slowly add dechlorinated hot water every five minutes via a syringe. Do not rapidly increase the temperature. Ensure a degree goes up every 45 minutes. Once the thermometer reads 10ºC, you can stop the hot water method and place them in a warm and insulated room. They should start to become active, but still not their usual self. As the temperature reaches over 15ºC they should become more active.
It is best to take your goldfish inside over cold winters. An indoor pond, aquarium, or temporary housing such as a kiddie’s pool or plastic storage container can be turned into a makeshift aquarium.
Has a Truly Frozen Fish Come Back to Life?
A goldfish that has been truly frozen for more than 5 minutes will have died. The experiments carried out have frozen the fish for less than a minute. The fish will be in pain, but still, be alive as ice crystals have not yet formed.
Keeping goldfish at their ideal temperature is the best precaution you can take. Although we may expect goldfish to survive being frozen, they do not. Care should be taken when attempting to revive them.
We hope this article has helped clear up some questions!
Featured image credit: Wirestock Creators, Shutterstock