How Long Can Fish Go Without Food

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How Long Can Fish Go Without Food

How Long Can Fish Go Without Food

Whatever pets you have, daily care is important, but we can not make sure we will be at home all the time. We might need to take a vacation to relax or travel to another city to do business. But the question is, what about our pets?

Unlike cats or dogs who will stop eating when they are full, fish keep eating all the time, whether they are hungry or full. If we are away from our fish for a long time, will they be ill or dead? How long can fish go without food? What should we prepare before we leave? How should we feed them when we are away? Let’s read this article and figure these questions out.

How long can fish go without food

Unlike fish kept in aquariums, wild fish barely eat daily since they can not find the food they need and they have to compete with others. Although being kept in aquariums, fish don’t change their traits, they can still be starved for some time, but as their owners, we should know how long this can last, so as to take care of them.

Normally speaking, fish that have been taken good care of can live 3 days to 1 week without food. But this is not a definitive answer, some fish can bear a long time while some can not. And that’s what we are going to discuss, what will influence how long can fish live without food.

Factors that influence how long can your fish survive without food

1. How long have you set your aquarium

The longer you set your aquarium, the longer your fish can go without food. Aquariums that have been set up for a long time are more stable, the water quality and parameters are more suitable for fish to live, the equipment works better and the fish have already known how to survive in this tank. So you don’t have to worry much about your fish.

But if your aquarium is newly established, you need to pay more attention since everything in the tank is unstable. It might be overstocked, the filter may don’t work efficiently, and the environment may stress your fish. If you leave your fish in such a fish tank for a long time, you are putting them into a dangerous situation.

2. The types of your fish

The types of fish will determine how long you can leave them. I’ve listed the number of days some popular aquarium fish can live without food, you can use them as a reference when you are planning to leave your pet fish for some time. But there is one thing you should notice, the fish on the list are adult, not juvenile, younger fish can not live so long without food.

  • Tetras: About 1 week
  • Oscars: 2-3 weeks
  • Koi fish: About 2 weeks
  • Mollies: Up to 2 weeks
  • Goldfish: Up to 2 weeks
  • Guppies: Up to 2 weeks
  • Angelfish: About 1 week
  • Betta fish: 1-2 weeks

3. The age and size of your fish

Just like humans, adults and bigger fish can bear hunger for a longer time. They have enough body mass and fat reserves to support their lives when you don’t feed them. For instance, juvenile angelfish can only survive 3 days without food, but adult angelfish can keep alive for about 1 week without any food.

4. Are your fish herbivorous or carnivorous

First, let me explain these two concepts to you. The herbivorous fish are those who eat plants, and the carnivorous fish are those who eat meat.

In the wild, herbivorous fish eat several times per day and they can always find food since the plants are easier to get. But the carnivorous fish will starve more often since they can only eat animals in the water, but animals will escape, which makes these fish more tolerant to hunger.

5. How active your fish is

Fish that are more active digest faster, which means they need to be fed more times with more food. So if your fish are active fish that like swimming around, you can not leave them for a long time, or you will go home and find they are ill or dead.

What preparations should you make before leaving

  • Adjust the brightness of the light

We all know that night is for rest, whether humans or fish will be less active at night. So the first suggestion for you is to adjust the brightness of your aquarium light, making the fish tank darker. In this way, you can make your fish swim less and digest more slowly. And they can survive longer when you are not home.

  • Lower the temperature

Lower the temperature is another way to make fish less active and digest less. A warmer environment is more comfortable for fish to live in, and it will make the metabolism of your fish faster. In cool tanks, you can feed your fish less often and give them less food. Therefore, when you are going to leave them for a vocation or business, lower the temperature by about 1-2 degrees. But pay attention, you can not lower two many, or your fish will be stressed about the temperature change.

How to feed your fish when you are away

What if you are going to leave longer and your fish can not insist that long? Don’t worry, there are some suggestions for you:

1. Fish sitters

In other words, fish sitters are people you can ask to help you feed your pets. They can be your neighbor, your relative, or a part-time worker. But it is very risky to ask them for help if they know nothing about fish-keeping. Asking a green hand for help will make your fish be overfed and the condition in your fish tank will change accordingly, which will hurt your fish to a certain extent. That’s why I will suggest you find an experienced person to help you take care of your fish.

2. Vocation feeders

Vocation feeders are also known as food blocks. They look strange but they have a long history in aquariums and are very economic. The vocation feeders will constantly release food to the tank for 1-2 weeks to provide food for your fish. But they do have drawbacks. They will continue to release food although the fish have got enough food, and they can not provide your fish with the food they need.

3. Automatic feeders

Buying an automatic feeder for your fish may be the best choice to realize a win-win, you can enjoy yourself and they won’t be starved. Automatic feeders have bins to store various food, and they can provide timely and quantitative feed according to the settings you made. There are many automatic feeders available in aquarium stores, but you should choose carefully because some feeders can only feed one type of food, which can not meet your fish’s demands.


Although fish can survive without food for a long time, it’s better to feed them regularly. So next time you plan to leave home for a long time, make some preparation for your fish. In addition, buy an automatic feeder for them to ensure they can be fed regularly. Then you can enjoy your vacation!

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