How Long Can Fish Go Without Food in An Aquarium? Find Out Everything About Leaving Your Fish Without Food Here

We’ve all felt the pangs of hunger at some point in our lives. At least we’ve felt hungry enough times to know that death by starvation is one of the worst ways to go.

So you can imagine what your fish has to go through when you leave it without food long enough for it to die.

Let’s say you need to travel but can’t take your fish with you. So, you leave and wrongly assume it will be fine by the time you return.

You may be wrong. While some fishes can go without food for extended periods, others will need to feed sooner to survive.

Most tropical and larger fishes can go for long periods without eating. However, determining how long they can last can be tricky.

Several factors determine how long a fish can go without eating, and they include age, size, and type of food the fish eats. Knowing how these factors work could save you from condemning your fish to a painful demise.

So how long can your fish species go without food, and what precautions do you need to put in place? Find out everything you need to know about leaving your fish without food in this article.

Let’s get started!

3 Factors That Determine How Long Your Fish Can Go Without Food 

Before you go on that trip, check for the following factors:

1. Type of Fish in Your Aquarium

Fishes typically fall into three categories based on their diet: 

omnivores, herbivores, and carnivores.

Carnivores eat meat and don’t need to get fed every day. They can keep on living and thriving without a meal for a long time. They catch prey to eat, and since that can take days to happen naturally, you can leave them without food. Cichlids is a great example of a carnivore. 

On the other hand, Herbivores consume algae and plants, while omnivores eat both meat and plants. All of the fishes in the last two categories need to eat frequently to survive. 

What’s the bottom line?

If you have carnivorous fishes, you can leave them for several days without feeding. All other types of fish cannot last that long and will need more regular feeding to survive.

2. When You Set Up Your Aquarium

You also need to consider how long your aquarium has been established so you can determine how long your fishes can last without food. 

More established and older fish tanks will make it easier for the fishes to survive in most scenarios. This is because the aquarium fishes are already used to the environment, and they know how to survive in it.

The risk of possible disaster is always much lower for aquariums that are old because there is an established ecosystem that works for all the inhabitants. This makes it easier for the occupants to survive for longer periods without any involvement from you.

Newer setups have more risk as the fishes are still adapting to the atmosphere of the aquarium. The ecological balance of the setup hasn’t been reached yet, so there might be issues like territoriality and waste production to worry about.

Here’s the deal:

The older your aquarium setup, the better your fish’s chances of survival if you fail to feed it.

3. How Long You Plan On Leaving Them Without Food?

Of course, how long you want to leave your fishes is the most important detail to consider. If you will be gone for only a day or two, there is no need to worry as your fish tank won’t turn into an aquatic graveyard by the time you return.

Some fishes can go for longer periods without eating. However, you will still need to make preparations regardless of how long you’ll be gone.

To ensure your fishes stay in good health, set the best possible conditions for them before leaving. For instance, you should change the water and clean the filtration system.

How to Prepare Your Aquarium for a Travel

If you’re planning a getaway and can’t take your fish along, you need to make certain preparations. If you take the following steps, your fishes will remain in good condition until you arrive.

1. Reduce the Temperature

To keep your fishes in good condition, you should turn down the temperature of your aquarium. Reducing the aquarium temperature will slow their metabolism, so they don’t need food as much as before. Reducing the temperature by a maximum of 2 degrees works fine.

2. Time Your Lighting

You should also set a timer on your aquarium light so that it only keeps your fishes illuminated when they need it. Set a shorter than usual daytime timer on your tank lights so that your fishes’ activity will be reduced. A decrease in their activity will reduce their consumption rate.

3. Handle the Aquarium Like You’re Not There

Before you set out to travel, treat your fish tank, and its inhabitants like you are not around. Use a “hands-off” approach for some time to monitor your fishes and see how they react in your absence.

Leave them without food for a few hours and see how they fare. You should do this a couple of days before you travel and after you have done the filter and water changes. This will get your fish used to living without food so they can survive after you travel. The test will also let you know how long they can stay without food and increase their food dependence by decreasing their appetites in steps.

Smart Ways to Feed Your Fish When You’re Away 

There are a couple of ways to keep your fish fed while you’re away for a long time. This section is necessary for those with young or small fishes that cannot survive without food for too long.

1. Fish-Sitter

Fish-sitters are people who look after your fishes and manage your tank. You could ask people around you such as friends or relatives to do this. Choose someone who is reliable and cares for your fish. 

There are also commercial fish sitters you can employ for an affordable fee. They are qualified people who can look after aquariums in schools, hospitals, offices, and other public places. You can get them to look after your fish while you’re away.

No matter who you choose as your fish-sitter, remember to give them a list containing their duties and any special needs your fish might have.

2. Automatic Feeders

These are devices that you attach to your aquarium to hold and dispense dry food to your tank inhabitants. You can find them online and in stores with various designs depending on your needs. You program them according to your fishes’ feeding schedule, and they do all the work for you.

You can set one to feed your fish daily or every few days, depending on the type of fishes you have in your tank. Automatic feeders are electric or battery-powered. The food could be in the form of pellets, flakes, or dried food items. Automatic feeders are one of the most efficient ways to feed your fishes even if you’re not traveling.

Something you should be careful of:

The main risk with this device is that everything else in the tank needs to be working correctly, especially the filter. If the filter is damaged and the feeder releases food in a polluted aquarium, your fishes could be in danger.

3. Vacation Feeder

A vacation feeder is also a great alternative if you can’t find someone to take care of your fish. Once you purchase one, pieces of food will be released slowly over a week or two. They are available in various sizes, shapes, and designs.

You can find commercially packed feeding blocks quite easily from fish stores or online. Start giving your fishes these blocks a couple of days before you leave to make it easier for them to transition.


1. How Often Should You Feed Fish Normally? 

Most fishes will be fine if you feed them only once a day. If you want to spoil your fishes, you can decide to divide their food and give them two smaller meals in a day. Young fishes that are still growing and slow grazers might need more access to food than adult fishes, so you might need to give them up to five small meals in a day.

The best time to feed your fishes is about 10 to 15 minutes after you turn the aquarium light on because that is when most fishes are awake. If you have nocturnal fishes, you can feed them at the end of the day when the light goes off.

2. What Quantity of Food Do Fish Need? 

This usually varies widely depending on the fish species. Sometimes, individual fish of the same species might even have different feeding habits. You will have to discover this on your own as you become closer to your fishes and understand them better. But a quick way to know if you’re not overfeeding your fish is to find out if they’re getting enough by checking their abdomen.

Look at the bellies of your fishes from the side and top views. Determine how round it is. A rounded abdomen means they are appropriately fed. This might be difficult to do, especially for the tiny fishes. So, you can look online for pictures of healthy fish corresponding to the species you have and compare.

3. Do I Need to Worry About Leaving My Fish for the Weekend? 

Your fishes should be fined under normal circumstances if you leave them for just a weekend or a couple of days as long as you follow the precautions above. Even if you don’t set up any automatic feeding system or get a fish sitter, fishes are known to stay without food for days without any problems whatsoever.

However, if you have fish fry in your tank, you won’t be able to leave them unattended for days. When fishes are just born, they need food for proper developmental growth. Nutrition in the first couple of days is paramount to the formation of their bones and overall health. Refusing to feed fish fry could cause sickness, deformities, and in some extreme cases, death.


How long your fish survives without food will ultimately depend on the type of fish, how long you intend to leave without food, and how long ago you set up your aquarium.

Regardless of your fish’s ability to survive without food, You will need to change your water and clean the filtration system before leaving, so they have the best possible conditions.

Any preparations you need to make concerning your fishes before you travel should be done gradually, so it doesn’t affect your fishes negatively. Give them time to adapt to whatever changes you’re making, and they’ll be better for it.

If you’re thinking of traveling for business or pleasure, we hope you now have an idea of how long your fish can stay without food. Remember to note special cases such as the presence of baby fish or sick fish in your tank.

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