Salmon jumping up river

Why Do Fish Jump Out Of The Water? (Comprehensive Answers)

Fish are truly fascinating creatures.

I remember watching my betta happily swimming around its tank one moment, then suddenly staring in awe (and worry) as it flew past me, out of water and onto my floor. It was shocking and a good lesson in just how much I had to learn about the natural behavior of my other fish species.

My jumping fish was able to make it back into his fish tank with little more than a bit of shock, but this can surely lead to more hazardous problems if not dealt with quickly.

Ever wondered “Why do fish jump out of the fish tank?”, read on for the answer to why this happens in the wild or in the home, as well as how to prevent this from happening in the first place!

Why Do Fish Jump Out Of The Water?

First and foremost, it’s important to note that there are a variety of reasons why you may see fish jumping.

Some fish species do it to hunt, others for more defensive reasons, and others may jump out of the water to find a better habitat.

Here’s an informative video by Dr. Jessie Sanders on the main reasons why fish jump

Some reasons why fish jump

It’s important to know just what contributing factors exist in your particular fish tank when trying to understand why we see our fish leap above the tank water.

Jumping to Avoid Predators

One of the most common reasons why fish will jump in the wild is to escape from predators.

Bigger fish are the biggest threat to smaller fish, as the general rule of thumb in the food chain is that if it can fit in their mouth, it counts as something to eat!

When fish run out of hiding spots in the water, jumping can be a great last-ditch effort to escape.

NOTE

Sea birds such as cormorants and albatross will actually rely on this instinct of fish jumping and wait above the surface for an easy meal! Even small birds such as seagulls will wait for prey and nab up anything that they see jumping above the water.

Fish often jump out of water to break the line of sight of their predators, as the water bends light and makes it difficult to determine from under the water exactly where they will land. This buys the potential prey fish valuable time to escape and live to see another day when they’ve run out of hiding places.

The flying fish, or Exocoetidae, are often pursued by giant mackerel and are extreme examples of fish leaping out of the water to escape.

While the defense mechanism to jump out of water isn’t present in all species of fish, it does occur both in wild and aquarium fish.

Adding several hiding spots to your aquarium can be a great way to ensure that skittish fish feel safe. In most instances in the aquarium, they will be jumping for another reason unless you have other fish who will prey upon one another.

Jumping for A Bite

One of the best examples of a fish that will jump out of water to chase food is the silver arowana, also known as the Monkey fish.

Underwater shot of a silver arowana
Underwater shot of a silver arowana

These fish live in the dark waters of the Amazon, and will use their powerful pelvic fins to jump out of water vertically, moving in a long arc to make an easy meal of the low-flying insects above the water’s surface.

NOTE

Monkey fish are sometimes kept in home aquariums, but keep in mind that these fish tend to fall back on the instinctual behavior to jump and find something to eat more than other species in your tank might.

Another example is the marbled hatchet fish, which is a surface feeder and an accomplished jumper. The hatchet fish will jump out of the water to knock down insects from low-hanging branches and leaves. As soon as the insect falls into the water, the hatchet fish has a tasty meal.

Fish that have adapted to jump about the water surface have the distinct advantage of having access to a food source that their water-bound brethren don’t: insects. These protein-rich bugs make for a great resource, and the small trade off of the energy required to jump is often advantageous for certain species.

Some fishing boats have even noted that fish, like the Asian carp, will jump into their boats to avoid the perceived threat from the sound of the engine – Talk about out of the furnace and into the fire!

Jumping for Love

The most famous example of fish jumping in order to find a potential mate is the many species of salmon found around the Americas.

These salmon will not only swim upstream for hundreds of miles, but will jump from a standing start to move their body around obstacles such as waterfalls, dams, and fish ladders. This is all part of a process called migration, and occurs in waters as diverse as the Great Lakes and the Pacific Northwest.

NOTE

Modern fish ladders are designed to allow fish to jump from one “step” to the other and avoid the potential hazards of having to swim all the way up a dam from harming their body.

Why Do Aquarium Fish Randomly Jump Out Of The Water?

Slightly different than many wild fish, aquarium fish may jump for a different variety of reasons created by the artificial constraints of being in a man-made environment.

For fish in the wild, jumping is a necessity

Many of the issues that may cause a fish to jump are preventable with proper tank set-up and maintenance on the part of the fish keeper.

Insufficient Oxygen

All fish require a proper amount of dissolved oxygen to be present in the water column in order to breathe.

As the water quality lowers due to the presence of high water temperature, uneaten food or decaying plants, and fish waste you’ll tend to see the oxygen levels in your tank lower in direct correlation.

TIP

Unsure of how much oxygen is in your tank? Consider purchasing an oxygen test kit to determine whether the amount in the aquarium is adequate for the size and number of fish that you’re trying to keep.

Seeing fish jump out of the tank, swim more towards the surface, and sluggish or erratic movements are all signs that your tank needs more oxygen. This is a problem that can quickly spiral out of control if not taken care of quickly, and can lead to a dead fish in the long run.

Water Quality

When asking “Why do fish jump?”, one of the critical components to look at is water quality.

Much like we would want to leave a room full of smoke in the case of a fire, dirty water, high ammonia levels, and generally poor conditions can lead to your fish jumping in order to find better water to breathe.

… one of the critical components to look at is water quality.

Using a water conditioner can reduce ammonia in a pinch. These drops act to bind to ammonia present in the tank and keep it from potentially causing ammonia poisoning in your fish.

When conditions for wild fish such as bettas are especially dire, such as during droughts, these semi-amphibious fish will jump from one body of water to another in order to reach a larger territory.

Close up of a betta fish
Close up of a betta

The presence of a specially adapted labyrinth organ actually allows them to breathe surface oxygen for 6-8 hours at a time, meaning they can handle extended periods between jumps.

Water Temperature and Jumping

If your tank gets too hot or too cold, some fish may attempt to jump in order to find a climate more to their liking!

Keeping a thermometer hooked up to your tank (along with generally knowing the conditions your particular fish prefers) is a great way to keep an eye on how things stand.

NOTE

Knowing the water temperature each fish you’re looking to have in the same tank prefers is very important prior to setting up a tank. Some fish may be incompatible if their temperatures don’t overlap, meaning you may need to either rethink your setup or plan on a warmer and a colder tank.

Crowded Tank

Having too many fish in one space is not only dangerous in terms of water quality, but it can lead your fish to become overly stressed.

These fish may jump in order to escape the crowded conditions, which can lead to stranding on dry land or hurting themselves against a lid.

Plan your tank size according to the maximum amount and size of fish you’ll have at one time in order to prevent this from happening.

How To Prevent Fish From Jumping Out Of Aquarium?

Given the variety of things that may lead your fish to jump, there are likewise several solutions to the problem.

Adding a lid to your tank is a great start, as it ensures that even if your fish do decide to jump, they won’t land outside of the tank and potentially become stranded.

Lit aquarium with a cover
A tank lid will help with your fish jumping issues

Water Conditions

Monitor water quality frequently, along with using water changes to make sure that conditions stay fresh. Using air stones, good filtration, and keeping your water free of hazardous debris such as fish waste and dead plants or fish will prevent ammonia from accumulating to dangerous levels.

Preventing Overcrowding

Plan your tank properly! If you notice that things are becoming crowded, it may be time to consider adding another tank to your collection.

Temperature

If you find that you need to increase the temperature in your tank, consider using a heater.

I recommend increasing the temperature gradually over the course of an entire day, rather than all at once. This will prevent more sensitive species from going into temperature shock, which can leave them more vulnerable to infections and disease.

How Do You Fix Too Little Oxygen In The Tank?

If you’ve found that your tank has an insufficient amount of dissolved oxygen for your fish to breathe, there are a few things you can do. Starting with a basic water change of 10-25% can be a great way to reintroduce oxygen and reduce the presence of harmful chemicals such as ammonia.

NOTE

Adding in an air stone or other form of air pump is a great way to add extra oxygenation to your tank for your fish to breathe while assisting with the removal of waste products with more water movement.

Secondly, you can clean the filters and ensure that waste is being scrubbed properly.

Close up of a fish tank with plants
Live plants in a tank can help with water quality

Adding in live plants can also reintroduce an extra source of fresh oxygen to the tank, as the plants turn CO2 present in the water into oxygen for your fish to breathe.

Conclusion

Throughout today’s article, we’ve answered the question of “Why do fish jump above the water surface?”

In some instances this may be to escape predators, catch food, avoid other tank inhabitants when things get crowded, or to search for better living conditions.

When trying to determine why fish may jump in your tank, it’s a good idea to look at the different species you have in your tank, as well as the conditions within it.

Feel Free To Share!

I hope you’ve enjoyed this post and that it has answered all of the questions you may have had about what causes fish to jump. As always, feel free to share this with any other fish fanatics you may know, and I wish you the best of luck on your continued aquarium adventures!

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Mollie Newton
Mollie Newton
Founder of PetMeTwice. I love all types of animals from fish to fluff-balls! I also enjoy writing short stories and helping train animals 🤩