How Long Can My Fish Go Without Food?

A responsible aquarist is prepared for anything, especially when it comes to leaving their fish alone. It’s important to know everything about your fish, in order to keep them alive as long as possible. 

In a situation, where you have to leave them alone for a few days, you should know how long they can go without food. The thing is, every fish is different, and a lot of factors can affect their metabolism. Generally, older fish can go longer without eating for a week or more. Younger fish, on the other hand, or should I say fin, need to be fed every day. Another factor is the components of their diet. A carnivorous fish does not need to eat every day, whereas an herbivorous fish needs to munch on something every day. Of course, these are just generalizations, you will need to keep some factors (that I’ll explain in detail, later) in mind.

With so many advanced gadgets, there has to be some sort of arrangement to feed your fish automatically? Don’t worry about any of these things because we’ve done all the work for you. All you need to do is get your reading glasses!

How Long Can My Fish Go Without Food? (Video)

Factors that affect the appetite of your fish

As mentioned before, the size and age of the fish really matter. Older and larger fish can go longer without food, as they have more body mass and fat reserves. This is why an adult chocolate cichlid will be safe fine without food for a long time as compared to a golden pencil fish.

Another factor is the nature of the diet. Carnivores do not eat every day. Actually, they can even endure a whole season without food in the wild. On the flip side, herbivores have to be fed every day as their diet has lesser nutrition and is pretty difficult to digest.

Even external conditions can alter the hunger of fish. Such as the age of the aquarium setup. Sounds quite odd, but stay with us for a while and it’ll make sense.

More established and older aquariums reduce the chance of potential disaster. The reason is, the fish are familiar with their environment and know how to survive in the aquarium. They will also be healthier if you’ve been taking care of them. Moreover, they would live peacefully among other members. Besides, a well-established aquarium can run smoothly for longer periods on auto-pilot.

For newer aquariums, it’s possible that an ecological balance may not have been reached. Meaning that the balance between aquarium volume and fish load hasn’t been reached yet. You, obviously need to have knowledge about your fish, but you also need to know your fish tank inside out. This will help your fish stay alive and healthy in your absence.

Another external factor is the atmosphere of the aquarium. You can turn the temperature down by a few degrees and put the daytime aquarium light for a shorter period of time, to slow their metabolism. A slower metabolism means that they would require less food. The shortened daylight period will help decrease any fish activity, which would normally increase their appetite. Even just changing the daylight timer to 6 hours from 12 will be sufficient.

Lastly, the most obvious factor is the period of time of your absence. If you’re going away only for a weekend, or even a long weekend, you won’t need to do any preparations. This is because many aquarists leave their fish without food for two to three days without any stress.

Automatic fish feeders

Obviously, this is a pretty common situation, which is why it has many alternate solutions because humans never stop coming up with more convenient gadgets.

An easy and stress-free solution to your problem is an automatic fish feeder. Many brands offer battery-powered or electric feeders that can dispense food items. Most of them are designed to hold and dispense dry food only, which includes flakes, pellets or freeze-dried foods. Some can dispense food twice a day for up to two weeks, and some can provide up to 4 meals a day. This is especially useful for baby fish that need to be fed every day.

Automatic feeders are a simple piece of technology. They work by rotating a compartmentalized plate or drum which follow a timer. The timer slowly turns the plate or drum, eventually dropping food into the fish tank.

There are not many downsides to buying automatic feeders, except that it’s a slight investment, even though you can get cheap ones really easily too. Although, in a scenario where your fish stop eating, the feeder will keep dispensing food and that may start to pollute the water.

Fish sitters

The name is self-explanatory. A fish sitter can be anyone, a kid who wants some money for himself or your friend that just really likes fish. Besides, there are also people who run an aquarium servicing business, but they may not be that common. It can be done by anyone, as long as you explain the process to them.

First and foremost, you need to explain how big of a job this is to your sitter. Do you have one fish tank or multiple ones scattered throughout your house? You will also need to explain all the details, obviously. For example, do you want the sitter to just feed the fish? Or do you want them to filter the tank’s water too? If you have any specific food requirements, such as feeding live food to the fish, make sure to mention that too. The simpler you keep the job, the lesser will be chances of any mishaps.

Next, you need to tell them how much the fish should be fed. An estimate would be fine unless you pre-measure the fish food. The sitter’s pinch could be your handful. The easier fish food for a fish sitter to feed is frozen bloodworms, as they come in little squares. All you need to do is tell them how many squares to drop in.

You can even make them a little note of everything they need to know, including your phone number; in case they have a question. You can even leave them a number of an experienced fish keeper or aquarium shop, as they have the answers to all questions. When you’re dealing with something like this, one sticky note can go a long way and give you the relaxing vacation you need!

Vacation feeders

If your fish need to be fed and you can’t arrange a fish sitter, you can use a vacation feeder. A vacation feeder is essentially a block of food packaged in a way so that it’s released slowly. These blocks come in a plethora of sizes and contents, and even the duration of how long they last, can differ. The only disadvantage to a vacation feeder is that your fish may not be used to the food in the vacation feeder.

Regardless, you can always try and feed your fish with the vacation feeder as a trial before you leave. Place one in the aquarium, then sit back and observe how your fish react. Over the next few days, you’ll be able to see the results and see if your species of fishes are compatible with the vacation feeder.

Feeding blocks usually have the number of days they last, written on the back or in the instructions. The directions about their size and how they should be used and even how many fish they feed will also be mentioned on the packaging. Prior to any purchase you make, be sure to read the description and directions so that it suits your fish.

How to prepare the fish tank for your absence

Before you leave for a month-long vacation, you need to prepare some things, so you don’t come back to your fish floating on the top.

Hold a trial period

A few weeks before leaving, you should conduct a trial fasting period to make sure you don’t starve your fish to death. Basically, all you need to do is; treat your aquarium as if you weren’t there, so leave it on auto-pilot. Keep checking it on a regular basis and observe how your fish do without any food or maintenance.

Do a major water change

If your usual water change rounds about to 30% – 40% to remove toxins and other debris, then a major water change would be around about 60% to 70%.

This way, the major cleanup of water will make up for the debris and waste that accumulates, when you’re not around.

Clean the aquarium 

After you’re done cleaning the tank water, it’s time to take a good look around and pick out any dead or decaying plants. This also goes for fish that are sick or dying. Any decaying or excess food lying around should be taken out as well; since it doesn’t belong there. These little decaying particles can spike up the ammonia levels in the tank, upsetting the balance. If these are left in the tank for too long, they could be toxic for the fish.

Managing the lights 

This step is only for those who have a lighting system in their aquarium. The lights should be put on a timer so that they don’t keep working all day. If you don’t have a timer (then you should really get one), just turn off the lights, but be sure that your fish get loads of natural sunlight. It’s best to avoid direct sunlight as it could harm the fish.

Cleaning the filter

You can clean a filter by rinsing it in a bucket with aquarium water. This will remove any debris and prevent a high level of ammonia. Do not replace the filter, as colonies of healthy bacteria that have accumulated on the filter will be wasted.

Choose and set up your alternative feeding system

If your fish do need feeding, and you’ve chosen your alternative feeding system, then make sure it has been set up properly (in case of the automatic or vacation feeder). Otherwise, if it’s a sitter, give them a thorough explanation of what their job is.

That’s all you need to know about feeding your fish. If you follow any of these methods, then you’ll come home to a beautiful and healthy aquarium. It’s much better to underfeed your fish rather than overfeeding it. Overfeeding has consequences that cannot be reversed. Wouldn’t you want to have hungry and healthy fish, rather than sick and dying ones? A little preparation can give you peace of mind during your vacation.


How often should you feed your fish?

Generally, most fish do fine with one feeding per day, as they require 16 to 24 hours to fully digest the food they eat. However, you can feed your fish twice very lightly. Usually, this depends on what species of fish you have, so it’s better to keep that in mind before accepting any generalized answer.

How long can you leave fish for without preparations?

Most fish are fine on their own for two to three days, as their aquarium is adept enough to take care of them. In fact, many experienced fish keepers leave their fish for a few days quite often. However, if you are leaving for more than three days, some preparation for food and cleaning will be needed.

Can you kill a fish by overfeeding?

Yes, you can kill your fish by feeding them too much. in most cases, they are given dry food which expands, when it reaches the water. The same happens when this food goes into the systems of fish. Some fish don’t even have a stomach, so overfeeding will kill them immediately. The leftover food can also disrupt the balance in the levels of ammonia in the fish tank.

What can I feed my fish if I run out of food?

If you’re out of fish foods, boiled vegetables, such as peas or small pieces of carrots will work. You can even feed them small pieces of seafood, such as white fish or shrimp. But it’s better to choose freeze-dried seafood instead of fresh seafood, as it can transfer infections to your fish.

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