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REVIEWED & FACT-CHECKED BY
Dr. Luqman Javed
Veterinarian, DVM
The information is current and up-to-date in accordance with the latest veterinarian research.
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Goldfish are hardy and adaptable fish, and healthy adults housed in the right conditions can go for up to 2 weeks without eating. However, just because they can go for a long period without eating, it does not mean that it is recommended to not feed your goldfish for extended periods of time.
Feeding your goldfish the right foods on a regular feeding schedule is important for their health and vitality. Goldfish need food as fuel to be able to swim and go about their daily activities normally.
If you are wondering if you can leave your goldfish without food while you are on vacation or if you are merely curious as to how long goldfish can survive without being fed, then this article has all the answers for you!
How Long Can Goldfish Go Without Food?
The exact duration of how long a goldfish can survive without eating depends on the current state of your goldfish’s health, the water temperature, and their age. If the goldfish is already malnourished and being fed an improper diet, then they have a shorter period of survival if they are deprived of food.
A healthy adult goldfish can go for approximately 1–2 weeks without food before they start to lose weight and develop adverse signs associated with prolonged fasting. It is important to note that goldfish that are hibernating can go much longer without food, although fancy variations of goldfish don’t have as great a fasting capacity as their common counterparts or koi.
It is also just as important to factor in the water’s temperature. Goldfish are cold-blooded (like all fish) and their metabolism is affected by the temperature of their environment. In warmer temperatures, their metabolism is higher, meaning their ability to go without food is not as good as it would be in ideal temperatures.
All goldfish are coldwater fish; fancy variations are best when kept in temperatures ranging from 68 to 74 °F (20–23.3 °C). The common variations (such as the Comet) can tolerate temperatures that are slightly below this and should be housed in waters maintained at 60–70 °F (15.6–21.1 °C).
Additionally, it is recommended that you perform a partial water change before deciding to fast your goldfish (for example, if you leave for the weekend and won’t be feeding your goldfish).
In the wild, goldfish will often go a few days without eating since they are grazers and eat whatever food is available for them. Their situation in captivity is different, though, as owners will usually feed our goldfish every day. Feeding your goldfish a variety of different foods each day is recommended so that you can ensure they are getting enough nutrition.
If your goldfish are not being fed, they will begin to forage for food amongst the substrate to find any morsels of food leftover from previous feedings. If you have a planted aquarium, you might notice that your goldfish will begin to eat your live plants because they are hungry.
In more severe stages where a goldfish has not been fed for a while, you will notice that they have a humpback appearance, this is because they are losing weight rapidly and their spines will start to stick out.
Many goldfish die as a result of improper feeding, diet, and/or portion sizes – which can be easily prevented by proper education.
That's why we recommend the best-selling book, The Truth About Goldfish, which covers everything about goldfish nutrition, tank maintenance, illnesses & more! Check it out on Amazon today.
Should You Fast Goldfish?
Fasting is a common practice amongst goldfish keepers because it is believed that by doing this your goldfish will have a lesser chance of developing the buoyancy problem known as swim bladder disorder (SBD). This theory has not been scientifically proven as an effective method to fix or prevent swim bladder problems from occurring, though.
The main belief stems from goldfish overeating (especially fancy-bodied goldfish that have rounded stomachs) may result in their full bellies pressing on their swim bladder and preventing them from controlling their buoyancy in the water efficiently.
Instead of fasting your goldfish, it may be better to feed your goldfish that have trouble with swim bladder disorders smaller meals throughout the day that contain easily digestible ingredients (a good quality sinking goldfish pellet is recommended for the bulk of their diet).
- See Also:
How Often Should Goldfish Eat?
All breeds of goldfish should eat at least once a day. The amount of food they eat will depend on their size, as larger goldfish typically eat more than small goldfish. Goldfish are omnivores so their diet should include both vegetative matter and animal-based protein.
High-quality pelleted food should be fed as a staple to your goldfish, and their diet can be substituted with other commercial foods such as freeze-dried worms, or you can feed them blanched vegetables a few times a week.
If you happen to be going on vacation or will be unable to feed your goldfish while you are away, they will be fine for up to 3 days, but if you’re away for longer, you should have a trusted friend or family member feed them while you are away. An alternative is to install a reliable food dispenser on top of their tank that dispenses some pellets at a set interval (such as once a day or once per 12 hours).
Submersible “feeding blocks” are not recommended, as they quickly spoil and deteriorate water quality, which is very detrimental for your fish. Goldfish can tolerate periods of fasting (within reasonable limits) much better than they can tolerate poor-quality water.
- See Also:10 Best Goldfish Foods
Conclusion
Healthy adult goldfish that are housed in a suitable environment with the proper water temperature and adequate filtration can usually go around a week without being fed with no adverse effects. Though some goldfish can tolerate longer periods of fasting (up to 2 weeks), this isn’t recommended by most fishkeepers.
The key to keeping your goldfish healthy is to ensure that they are being fed a balanced diet rich in the vitamins and other nutrients that they need to remain healthy. Goldfish are intelligent, and their biological clock seems to tell them exactly when feeding time is, which you may notice by their excitement and gasping mouths near the area where you frequently feed them.
You should stick to feeding your goldfish regularly and not purposefully deprive them of food, as it may do more harm than good. However, a quick trip out of town (for, say, a weekend) shouldn’t pose too much of a problem for your adult goldfish. Periodic fasting may offer some anecdotal benefits for their swim bladder as well.
See also:
- Why Is Your Fish Not Eating
- Why Your Goldfish Is Not Eating: 10 Vet-Reviewed Reasons
Featured Image Credit: Zinaida Zakharova, Shutterstock
Contents
- How Long Can Goldfish Go Without Food?
- Should You Fast Goldfish?
- How Often Should Goldfish Eat?
- Conclusion
