Can You Fast Betta Fish?- What Happens If You Do?

There’s no doubt you love your Betta fish. But the truth is it’s hard to be consistent with the feeding schedule without any help. Especially if you get stuck outside without having the time to appoint a fish-sitter. In those situations, you might wonder, can you fast a Betta fish? And what happens if you do?

Betta fish can fast for 3-4 days easily without any sign of physical weakness. Carnivorous fish like Betta usually hunt for food in the wild; they are used to not having a good catch every day. But you shouldn’t let your pet Betta fish fast for more than one and a half weeks.

Now that you are sure the fish don’t die doesn’t mean you stop preparing at all. In fact, preparing your fish prior to a fasting period will ensure your pet doesn’t get hurt in the process. So, if you are concerned about your Betta, keep on reading.

Key Takeaways

  • It’s alright to leave your Betta fish without food for 4-5 days.
  • In the worst-case scenario (if there’s an emergency), your Betta fish can survive up to two weeks without food.
  • But fasting for 10-14 days can cause several health-related problems like discoloration, lethargy, increased stress level, etc.
  • Changing the water is a must before leaving the Betta fish, even for a few days.
  • The best possible way to avoid fasting your Betta is to find an automatic fish feeder.
blue yellow color gorgeous betta
Owner: Jody Tourand

Is It Okay To Fast Your Betta Fish?

Not giving a daily meal to your pets seem cruel. But it’s actually not. In fact, fish like Betta Splendens can easily fast for 3-4 days without any significant change in their behavior. But why does the lack of food don’t bother them?

Well, because Betta is carnivorous. And the majority of carnivorous (meat-eaters) fish in the wild have to hunt their food. If they fail to catch something, the only option is to starve. So, Bettas are pretty used to not having meals on a daily basis.

That means if you have to leave the aquarium unattended for 3-4 days, you don’t need to worry about your Bettas. You are good to go as long as you have cleaned the tank and checked the water condition (temperature, pH level, ammonia level).

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Now, what is the maximum number of days a Betta can sustain without food? Reportedly, you shouldn’t leave them without food for more than 14 days. Depending on your Betta’s age, health implications, and water condition, the fasting days should end within 10-14 days.

Even though your Betta might be alive by then, it might show signs of lethargy, dull temperament, etc. We highly recommend you don’t wait 10-14 days to feed your pet. If you are unable to attend them, try and get a fish sitter.

Is There Any Benefit To Fasting A Betta Fish?

Fasting is common in nature. There are very few wild-fish that gets to eat their favorite brine shrimp every day. In that sense, there’s no harm in keeping your Bettas fasting for a few days when you are not around.

But is it helpful for their health? Well, that’s not very clear. The most accurate answer is that if you don’t have to fast them, don’t. there’s no major health benefit to fasting for your fish. Lack of food can increase stress in a matured Betta.

However, there’s one small health benefit as well. Fasting helps when your Betta has a tendency to bloat. It happens when the fish tries to eat large portions in a hurry. For example, one Betta owner shared the story of how his Betta gulped down three fish pellets and then went to hunt a shrimp. The result was an upset stomach and a severely bloated stomach.

The good thing is, such bloating is temporary and usually goes away the next day. But it’s a good practice to let your Betta fast once you have noticed such bloating. It calms down the digestive function and gives the body time to adjust to all the excess nutrition.

Apart from this specific bloating remedy, there’s no other need for fasting. Yes, if you feel like you are overfeeding the fish, just reduce the portion/meal size instead of letting it fast.

Note: Another benefit of fasting is that it allows you Betta to feel what it’s like in the wild. they can stay closer to their natural eating routine.

white red betta collage with two pics
Owner: BettaGobs Farm

5 Things To Consider Before Fasting Your Betta Fish

While you are preparing the fish to fast for one or more days (without you in the house), check these five things first.

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1. Have You Changed The Water?

If you plan to fast your Betta fish while you are away from home, it’s wise to change the water. Usually, water change is a frequent task if the tank size is less than 3 gallons. However, you don’t want your fasting pet to stay in a tank full of toxins (like ammonia). Since it is going to search for food habitually, it might mistake the waste for food. The harmful fish poop can impact your Betta’s health negatively.

So, cleaning all the waste from the aquarium is recommended just before you start the fasting ritual. It will ensure the fish are fasting and not chewing on their poop for fun.

2. Is The Tank Large Enough?

Keeping bettas inside a fishbowl is, sadly, a very common practice. Even though experts discourage such practices, owners have found a way to convince them. The technic is to clean the bowl more frequently. So, if you change the water every 7-10 days in a 5-gallon tank, the small fishbowls need to be cleaned twice in that particular time. It reduces the impact or density of toxins inside the fish tank.

Since the Bettas are to be left alone without a caretaker, you better shift them to a larger home. That way, you don’t have to appoint a person to change the water after 2-3 days. We recommend having at least a 5-gallon tank for your betta.

Note: Please remember that we are suggesting a tank switch only if you decide to leave the house for some days. If you stay inside the house or appoint a fish feeder, only cleaning the tank time-to-time would be enough. You don’t have to buy a new tank.

3. How Does Your Betta Usually React To Fasting?

Every fish in your tank is different, including the Siamese fighting fish or Betta. Even though it says on the internet that a Betta can go without food for 10 days, your pet might not have that ability. So, you better check Betta’s health condition before putting it on fasting mode.

 Start with a 1-day fasting trial. Don’t over-feed the fish prior to or after the test. See whether you see any adverse results or not. If not, wait for a couple of days, increase the fasting period up to 3 days. Examine how the fish reacts, whether their body starts discoloring or not. Do they look sick or have any skin or digestion problems? If not, your fish is safe to leave without food for a couple of days.

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4. Is The Filter Working Properly?

Betta fish don’t usually depend on artificial filtration systems. But it helps to have that device in your Betta tank. However, if you have that device, ensure it’s properly clean and working fine. Sometimes debris gets stuck in the filter, halting the process. And, if it happens when you are not there, the tank can get filled with filth pretty soon.

Another tip we have is to attach a lighting system that can be controlled through a remote. Or, set the light in a way so it’s only active for a few hours. It helps to let the fish know when it’s day or night. Usually, Bettas love sleeping in darkness (during the nighttime). So, not having enough darkness will reduce their sleeping cycle and increase their stress level.

5. Have You Installed A Heater?

We put too much emphasis on filters. But “heat” is more important than filtration. Yes, you heard it right. And it’s even more crucial when the fish are in fasting mode. So, try and get a heater for your Betta. Adjust the heat to 75 to 80 degrees Fahrenheit. That’s known as the ideal water temperature for Bettas.

 However, we have a small tip for you. Instead of setting the temperature close to 80 degrees, go a bit lower (for example, 72 to 75 degrees Fahrenheit). What it does is keep the water cooler than expected. It helps to lower the metabolism rate inside the Betta’s body. Because the body tries to mimic the water temperature. It also causes the fish to lose less body fat. So they can finish the fasting cycle without any issues.

Before You Leave!

We know exactly how worried you are regarding your fish’s diet. They are tiny in comparison to other pets (cats, dogs). So, you have to be extra careful while choosing a treat for them. For example, many people like offering fruits like oranges to their Betta. If you know Betta-owners who do this (or you do yourself), here’s our discussion on whether it’s okay to feed orange to your Betta fish or not.

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Muntaseer Rahman

About Author

Hello, I’m Muntaseer Rahman, the owner of I’m passionate about aquarium pets like shrimps, snails, crabs, and crayfish. I’ve created this website to share my expertise and help you provide better care for these amazing pets.


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