How Long Can Fish Go Without Eating?

As pets, fish require care and attention, too. Even when they seem to do nothing than swim all day, daily. So, if you’re going away for several days, you should look into continued care for your pets.

Feeding them regularly is crucial for their survival. Besides, you don’t want to come back from your travels and find your beloved fish already dead because of apparent starvation.

Read Also: How Long Can A Betta Fish Go Without Eating?

It Depends on Fish’s Diet

First and foremost, the number of days that fish can survive without food depends on its type. Fish can be categorized into four categories based on their diet, namely:

  • Carnivores – such as cichlids and sharks, eat other animals.
  • Herbivores – They eat algae and plants, such as seaweed.
  • Omnivores – consume both animals and plants.
  • Limnivores – They prefer mud-based foods.  

The distinction between these categories influences the feeding frequency for the specific fish you have in your aquarium.

Carnivorous fish generally survive for longer periods without feeding in comparison with other types of fish. Even in the wild, they can go for days without catching prey and, thus, they can withstand prolonged periods with little to no food.

But the herbivores and limnivores require frequent feedings to survive. In the wild, these creatures often use their time foraging for food and eating.

It is partly because their food sources (e.g., plant matter and algae) have lower nutritional value than meat and require more time to digest. Both herbivores and limnivores should then be fed every day.

It is because a single day without food will have adverse effects on their overall health.

Furthermore, the size and age of the fish also influence the frequency of feedings. While there are exceptions to the rule, older and larger fish can survive for long periods with little to no food in comparison with younger and smaller fish.

The former have more fat reserves and body mass that they can use during lean periods; baby fish, in fact, cannot survive a day without food. 

Steps In Increasing Their Chance of Survival

Before you go away, you can adopt simple yet effective steps in ensuring the survival of your pet fish while you’re away.

Give Them A Well-Established Aquarium

Keep in mind that a well-established aquarium with an ecologically balanced environment is the best when leaving it unattended for days on end. Indeed, fish shouldn’t be left unattended in a new tank for extended periods.

It is because they have fewer chances of survival; the algae growth in an “old tank” contributes to it. 

Change the Water and Clean the Filter

Minimize the risk of fish being hungry and in a dirty environment when their tank is left unattended. You can make a partial water change about three days before your departure, but be sure thoroughly clean the tank’s filter. 

You should also feed your fish well for at least seven days before your departure so they can build up fat reserves and body mass.

Note: You can also determine the number of days that your fish function relatively well with no food, a trial period of sorts.  Afterward, you can decide whether to hire a fish sitter or use an automatic food dispenser depending on the number of days you will be gone.

You may also have these options during emergencies like flight delays and bad weather. 

Slow Down Their Metabolism

Fish with slowed-down metabolism have less desire to seek food because their energy requirements are lower. You can achieve it by:

  • Decreasing the amount of light they receive within a day, say, from 12 hours to 6 hours. Use a timer for this purpose.
  • Reducing the temperature for only a few degrees.


We also suggest using automatic feeders and feeding blocks instead since these are more affordable than fish sitters, not to mention that these can be used several times. Try the Zoo Med Original Banquet Feeding Block that have high-protein micro-pellets suitable for bottom feeders. You may also like the ShinePick Automatic Fish Feeder, an easy-to-install device that allows for adjusted amounts of fish food.