How Long Can Fish Go Without Food in an Aquarium?

How Long Can Fish Go Without Food in an Aquarium

Are you going on vacation? Are you worried about who will feed your fish? It’s not impossible to take your fish along with you, but it’s not practical, especially if you have a tank full of fish.

You’re presented with the dilemma of whether you should leave your fish alone or under someone else’s care.

In case you don’t find anyone to take care of your fish, you have no choice but to leave your fish alone.

There are a variety of factors that contribute to the survival of your fish while you’re away.

It’s important for you to foresee the wellbeing of your fish beforehand and make all the necessary preparations to keep them alive and thriving.

How Long Can Fish Survive Without Being Fed?

This is a very common question amongst individuals who are planning to travel soon.

Many tropical fishes can survive a considerably long time period without having to eat.

It’s not easy to determine the exact duration of time as it depends on multiple factors—we discussed some of the factors above, and some other factors entail the size and the age of the fish.

The rule of thumb is that older and larger fish find it easier to survive without food for longer time periods as compared to younger and smaller fish. This is because older and larger fish tend to have more body mass and fat reserves. Considering this, an adult cichlid will live longer without food as compared to a golden pencil fish.

Additionally, if your fish are herbivores then they’ll probably have to feed every day as they have to eat a lot to get enough nutrition.

You can have a trial fasting period for your fish before you head out on your vacation as this will help you exactly determine how long your fish can go without food.

Factors that Determine How Long your Aquarium Fish can Survive without Food

Here are a few factors that determine how long your fish can survive without food.

Consider these factors and prepare everything before you head out for your vacation.

What Kind of Fish Do You Have?

There are different types of fish that fall into four distinguished categories based on their diet.

The four main categories are herbivore, omnivore, carnivore, and limnivore.

While carnivores, such as cichlids, eat meat, herbivores, such as tangs, only consume plants and algae.

Omnivores tend to consume both meat and plants. Limnivores consume mud-based food.

In short, the feeding frequency of the fish depends on the type of fish you have.

Generally, carnivores tend to survive longer without feeding as compared to other fish types.

Since they can go days without catching prey, they’re designed to survive through long periods of food scarcity.

The other categories of fish demand food more frequently in order to survive—especially Limnivores and Herbivores— they spend more time eating or looking for food.

How Long Has it Been Since You Setup Your Aquarium?

If you’re departing on your journey and have planned to leave your fish behind, this factor is extremely important.

Is your aquarium well-established, old, or relatively new?

Apart from a few reservations, the more well-established and older a fish tank is, the longer it will survive without incurring any disastrous event.

The main reason behind this is that the inhabitants of that aquarium are already aware of how they can survive in it.

The fish have also been healthy for a long and all members of the fish community are getting along well with each other.

So, if the aquarium is established well, then it can run smoothly for longer time periods on auto-pilot.

For more recently installed aquariums, there’s a high chance that the ecological balance between the aquarium and the fish load hasn’t reached yet.

There may also be behavioral overstocking in the aquarium, such as territoriality or the production of waste.

You should be well-informed about the set-up of your aquarium as it will become easier for you to foresee how long your fish can stay without food.

It’s considerably risky to leave your fish tank unattended or unmonitored while it’s still trying to establish an ecological balance.

For How Long Will You Be Away?

Another crucial factor to consider before you leave your fish tank is determining the time you’re planning to be away.

You don’t need to worry or prep excessively for you’re only going to be away for the weekend.

Many people tend to leave their aquariums without any food for around 2 to 3 days.

So, we can easily establish that your fish can survive a weekend holiday without feeding.

However, to make sure that your fish remain healthy while you are away on the weekend, you should clean the filtration system and change the water a few days before leaving.

This will ensure that the fish survive the weekend without food and remain healthy.

Preparing your Fish For When You Are Away

If you’re planning to leave your fish for a longer time period, you should take some precautionary steps to ensure their well-being upon your return.

Treat the Aquarium As If You’re Not Around

You need to make your fish accustomed to certain environments so that they don’t experience a major change when you leave for your vacation.

Maintain a ‘hands-off’ approach for a while to observe the behavior of your fish.

Don’t feed or maintain the tank for a while to see how the inhabitants are coping.

This plan should be executed a few days before you leave and before you conduct the water and filter changes, as mentioned before.

Lower the Temperature

Turning down the temperature reduces the metabolism rate of your fish, hence reducing their need for food.

Before you leave, you will probably set a timer on the aquarium lights.

Make sure you set a shorter than normal daytime timer on your fish tank lights as that will limit the activity of the fish and decrease the need for food repeatedly.

Feeding Your Fish While You Are Away

We’ve already established that taking your fish pets with you on your vacation is a bad idea.

However, if you have young and small fish in your fish tank, there may be some measures you can adopt to ensure they’re well-fed while you’re away.

However, this may pose a few hardships, especially considering your fish have special dietary requirements.

Automatic Feeders

These automatic feeders that can be attached to your aquarium are designed for holding and dispensing dry-food items.

They are available in a huge variety of designs and can be programmed according to the feeding schedule of the fish.

It can be programmed to feed your fish once a day or every few days. They function by rotating a compartmentalized plate that relies on a timer.

While the idea of installing an automatic feeder may sound appealing, it is crucial to comprehend that in case the filter fails to work, food will be dispensed in a polluted aquarium.

This can even result in a life-threatening situation for the fish.

Vacation Feeders

Can’t find someone to look after your fish while you’re away? Another great alternative is a vacation feeder.

Vacation feeders are available in multiple designs, shapes, and sizes and cater to the feeding needs of your fish for specific time periods.

Commercially packed feeding blocks are slowly released inside the aquarium.

The main drawback of using vacation feeders is that they don’t dispense the kind of food your fish are used to eating.

To ease their transition, you can introduce your fish to these eating blocks a few days before you leave for your vacation. Once they are used to these eating blocks, the transition will not be that hard.

Fish Sitters

A fish-sitter who knows how to manage a fish tank is also a good option.

Anyone can be a fish sitter such as your relatives, friends, or kids who’re looking to earn some extra cash.

You need to choose someone willing and reliable to do the job.

Also, for an affordable fee, you can find commercial fish sitters who take care of aquariums in places such as hospitals, schools, offices, etc.

They can do the same for you while you’re away on vacation.

If you are leaving your fish in the hands of your relatives or friends, make sure that they tend to the aquarium once every 3 to 4 days.

It’s best to make a list of things that need to be done and hand it over to them so that they don’t forget the things they have to do.


While many fish can survive a few days without being fed, it’s uber-important to remember that you have to maintain a regular maintenance schedule before you leave.

Being well-aware of the type of species that you have is the first step to ensure that your pets survive while you are away on vacation.

A well-maintained aquarium will ensure that your fish can get through their fasting period without any disastrous effects.

With proper preparation and planning, your fish will survive and also be healthy upon your arrival.

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