Why do Fish Jump Out of the Tank?

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If you’ve never had a fish tank before, you have a lot of catching-up to do in terms of understanding the basic fish behavior.

While different fish species have different behaviors and requirements, they often share a lot of similarities. One of them, which we will discuss today in more detail, is the ability to jump out of the water.

Not all fish do it, but enough of them engage in the behavior to justify writing a more extensive article on the topic. Or conduct numerous studies, trying to figure out what’s causing the behavior.

So, let’s delve deeper!

Fish Jumping Behavior

This is a fascinating topic, especially since this unique fish behavior is still not well understood. It’s also worth noting that wild fish may jump for different reasons compared to captive-bred ones.

In essence, this is an evolutionary behavior supported by the fish’s lifestyle. More importantly, if one fish species qualifies as a jumper, it will remain a jumper even after being raised in captivity for multiple generations.

This is because the underlying drives that influence the fish’s behavior are deeply ingrained in the animal’s instincts.

But why do so many fish jump out of the water, and what can you do about it?

Reasons Fish Jump from Aquarium

Nobody wants to see their fish jump out of the aquarium. The act of jumping itself may make for an interesting spectacle, but it’s not worth the risk of losing your fish. However, in order to discourage or prevent the fish from jumping, you must first understand what drives its behavior.

Here are several potential causes:

Unfit Tank Conditions

Different fish species require different aquarium conditions, depending on the species. Ideally, you want to house your fish in a natural-looking setup that mimics their wild habitat.

Environmental parameters are the most important, especially temperature, pH, and overall water quality.

There are very few fish species that don’t mind water quality, to a point. Bettas come to mind, as these fish possess a labyrinth organ that they can use to breathe at the water’s surface. This evolutionary feature is there precisely to allow the fish to live and even thrive in poor water conditions. The fact that you should clean the fish tank and change the water regularly is a different topic.

The idea is that if the fish is uncomfortable with its water parameters, it may attempt to escape the ecosystem.

And the only way to achieve that is by jumping out of the tank. So, always check water parameters first if you notice that your fish exhibits unusual jumping activity.

Tank Size

40 gallon breeder tank

This is an obvious one, but it needs to be mentioned anyway. Different fish species have different space requirements. Guppies need 2 gallons per fish, goldfish need 30 gallons per fish, Oscars need 55-70 gallons per fish, and so on. If the fish doesn’t have sufficient space available, it may feel stressed, causing it to look for a way out.

This is an even more pressing problem if you have a community tank with different fish species present. If they feel overcrowded, they may become stressed and aggressive towards each other because fish can be just as territorial as other animals.

Aggressive Tankmates

Fish aggression is common in any tank unless you only have one fish. The moment you introduce another, the game is on. The presence of at least 2 fish in the same ecosystem necessarily leads to the creation of a balance of power, as the fish will compete over space, food, breeding rights, and dominance.

Some species are more aggressive and territorial than others, but even docile and easygoing fish can exhibit violence if stressed, overcrowded, starving, etc.

Fish aggression is generally normal in any group or community tank, but there are times when it may go out of bounds.

Some fish may turn into bullies and harass the smaller and weaker specimens, forcing them to look for a way out. If they can’t hide, they may attempt to escape the tank by jumping out.

However, it’s worth noting that placing a lid on the tank doesn’t solve the problem. Because the problem is not the fish jumping out but the excessive violence that’s causing them to want to do that.

So, you should work on mitigating the fish’s relationships. Otherwise, the bullied will simply become stressed, which will affect their immune system and lead to parasitic or bacterial outbreaks.

It’s also normal for stressed fish to exhibit loss of appetite and lethargy and even die in some cases.


Some fish may jump out of the water to remove skin parasites or due to the physical discomfort associated with skin infections, bacterial or otherwise. This is also a normal behavior, but it’s more prevalent among fish living in stagnant or slow-moving water.

That’s because these bodies of water contain more parasites, bacteria, and leeches than fast-moving streams. This only leads to one natural conclusion: having a good tank maintenance routine is vital.

Your tank is the very definition of an ecosystem with stagnant waters. Get a good filtration system in place to ensure some water movement, clean the tank regularly, and perform regular water changes (generally weekly, but it depends on the situation) to keep the system clean and healthy.

Also, monitor your fish for signs of parasites and bacterial infections and medicate them properly in case of infection.

Quarantine may be necessary in such situations to move the fish into a controlled environment for better care and for preventing an outbreak.

Fish Communication

Yes, fish communicate with each other via various channels, especially color and behavior. One such behavior is the jumping one, which can transmit different intentions like mating, territorial dominance, or intimidation. Not all fish use this ‘language,’ but some do.

If your tank fish tend to jump out of the water despite the lack of any obvious reason for their behavior, this might be a potential explanation.

Maybe your fish simply exhibit territorial tendencies or are in full breeding season. Keep an eye on your jumpers to see whether your predictions are accurate.

Predator Evasion

Many fish resort to various predator evasion tactics, one of them being jumping out of the water repeatedly. This behavior can confuse their attackers because the fish will simply disappear out of the water, even if for a short amount of time.

Now, you might argue there are no predators in the aquarium, right? Right and not right. This takes us back to the ‘Aggressive Tankmates’ point because aggressive tankmates are basically the closest you can get to actual predators. The bullied fish will behave pretty much the same.

Also, fish have well-developed defensive instincts. This causes them to attempt to jump out of the tank when scared by sudden movements, noises, or lights near their tank.

So, keep that in mind when looking for the best spot for your aquarium.

Fish Species that are Likely to Jump

Now that you know why fish tend to jump out of the tank, it’s time to find out which fish are more likely to jump. Depending on your situation and setting, you might want to avoid those.

Here are some examples to take with you:

  • Bettas – Believe it or not, bettas actually tend to jump out of the tank due to poor water quality. This may come as a surprise, as we’ve just discussed how these fish are well-adapted to poor environmental conditions, but there you have it. If the water is too dirty, your bettas may attempt to leave the enclosure. They can also jump when scared or looking to intimidate other bettas. This is why most people keep only one betta fish per tank.
  • Guppies – Yes, the notorious guppy can jump out of the tank when overcrowded, kept in poor water conditions, scared, or even bored. Guppies require a healthy and lush ecosystem so that they’re always engaged and calm.
  • Swordtails – These are also notorious jumpers. Swordtails are more likely to jump out of the tank when stressed, overcrowded, or if the water temperature is too high.

Goldfish and neon tetras may also exhibit similar behavior in some cases. When it comes to wild fish, the most famous jumpers include species like the tarpon, sailfish, bonefish, and salmon, which all jump for various reasons.

The salmon is among the most interesting cases, as these fish jump as means of locomotion when swimming upstream.

They’re so powerful that they can jump over obstacles like rocks, tree trunks, and small waterfalls and rapids.

Preventing Fish from Jumping

There are several ways by which you can prevent your tank fish from jumping out. But there’s likely no way that you can prevent your fish from jumping completely.

Some species are simply born jumpers, and they’ll do it in spite of all your efforts to the contrary. Which is fine, so long as the fish doesn’t get out of the tank.

With that in mind, here are several strategies you can use to keep your fish in the tank:

  • Ensure adequate maintenance – Clean the tank regularly, remove fish poop and food leftovers, remove algae residues, and change 20% of the tank water at least once a week.
  • Offer an adequate diet and meal plan – Your fish should always be content with their food, both in terms of quality and quantity. Learn your fish’s nutritional needs and eating habits and stay true to their requirements.
  • Establish a safe community – It’s normal for fish to fight over pretty much anything, including space, food, females, dominance, you name it. This is a natural behavior that you can only mitigate but not erase completely. Monitor your fish population to make sure that their interactions remain somewhat cordial.
  • Craft the ideal layout – Understand what your fish need in terms of habitat layout. Some prefer more open spaces, others are fond of a lot of vegetation, and others need rocky caves to lurk around. The substrate is also important, depending on your fish’s preferences, so keep all these aspects in mind if you want your fish to remain healthy, happy, and chill over the years.
  • Secure the tank – A tank lid is almost always necessary to prevent the fish from jumping out. Just make sure it has holes in it to ensure proper aeration.


A lot of fish are known jumpers, and there’s little you can do about it. You can discourage them from jumping as often, but you won’t be able to train them not to do it anymore.

So, you must find ways around that, then. Consider my today’s tips and keep an eye on your fish to gauge their behavior, temperament, and any problems that may stress them to the point of jumping out of the water.

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.

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