Why Do Fish Jump Out Of Aquariums? Can You Stop Them?

If you’ve kept fish for a number of years then I’m sure you will have experienced the sad sight of seeing one of your precious fish all dried up and dead on the floor.

It’s a sad moment for any aquarist but it happens all too often. But why do they do it? Why do fish jump out of aquariums?

We provide the best possible aquarium and nice plants, rocks and environment to live in yet they still jump out of the aquarium.

So, why do they do it? Let’s take a look at all the possible reasons. There are many reasons why fish jump out of aquariums and it’s hard to put your finger on the exact reason. But we have a few ideas. So, read on.

Why do fish jump out of aquariums? Fish will behave in strange and unusual manners when they feel threatened, stressed or sick. You also have to remember they are confined within the water you provide. So, if the water conditions are not suitable, it could be a reason why your fish are jumping out of your aquarium.

Do Newly Added Fish Jump Out Of Aquariums?

Adding new fish to your aquarium is exciting but risky

I have worked in the aquarium industry for over 30 years now and one of the best parts of the job is receiving your consignment of new fish once a week. Unpacking and adding these newly imported fish is very exciting but also a little nerve-racking.

When fish are added to a new aquarium it’s the most vulnerable time for these fish. They are often in a state of shock and wary of their new tankmates. So, they often go into hyper-drive and swim around the around in a state of frenzy. Scared, and confused. This can often lead to them jumping out of the aquarium within seconds.

Small fish like Neon Tetras come in bags with over 100 fish per bag and it’s not uncommon to lose most of them if you don’t add them into their new home in the correct manner.

We’ll teach you how to correctly add fish to their new home later in this article.

7 Reasons Why Fish Jump Out Of Water

There are many reasons why a fish would jump out of their aquarium to their death. However, we have narrowed it down to the 7 most obvious reasons why they might do such a terrible thing.

  1. Food: Fish often jump out of aquariums to capture food
  2. Poor water quality: No one likes to live in poor living conditions and fish are no different. They will often jump out of the water to try and find better water conditions
  3. Lack of oxygen: Lack of oxygen must be the same feeling to a fish as a human would feel being suffocated. A natural reaction would be to try and escape to better conditions
  4. Preditors: Small fish will do anything to avoid being eaten. Can you blame them? And vaulting out of an aquarium could be the last resort
  5. Accident: Like all walks of life, accidents can happen and a fast-swimming fish near the surface could accidentally leap out of the water
  6. Temperatures: Incorrect water temperature or pH levels could also cause their death by jumping
  7. Stress: Stress is, believe it or not, one of the biggest killers of tropical or pet fish. Stress from preditors, water conditions, diet, and many other things can cause fish to leap to their death
fish jumping out of water

The Study Of Fish Jumping

There have been a few scientific studies on why fish jump out of aquariums. Often related to feeding or breeding habits. A famous study carried out by scientists Daphne Soares and Hillary S Bierman watched and studied the behaviors of guppy fish after one accidentally jumped into her cup of tea whilst she was sitting next to the aquarium.

Their study and findings

Daphne Soares was inspired to research and study these amazingly popular tropical fish and why they jump; after one day, a guppy soared through the air and landed in her cup of iced tea.

They began to study these fish by using a high-speed digital video camera to capture guppies in the act of jumping out of the tank. Their initial findings were very interesting. The guppies actually backed up prior to the jump to gain speed for their launch.

This suggests that not only is leaping out of the tank done on purpose, but it may actually serve a function. The results of the study showed that a fish as small as a guppy can achieve a leap several times its body length.

You can read their results and findings here in their published paper.

Why We Think Fish Jump Out Of Aquariums

As you read above, there are many reasons why fish will jump out of the water and even jump out of the aquarium.

After 30 plus years (is it really that long?) in the aquarium industry, I have my own thoughts on the real reason. I’ll explain in more detail on each possible reason. All of which can cause your fish to leap out of their aquarium but we’ll never know which one caused your fish to do so.

Unless you can bring them back from the dead or have CCTV on your aquarium 24 hours a day, you’ll never really know. But if you can narrow it down, maybe you can take steps to help prevent it from happening again.

1. Water conditions

This is a rather broad topic but generally, poor water conditions will be one of the main reasons why your fish are not happy and decide to jump out of the tank.

High levels of ammonia, nitrites, and nitrates in the fish tank is a sign that all is not right. Unsuitable water is caused by overfeeding, poor filtration, lack of water changes or an overstocked aquarium. Again, there are other reasons but these are the main factors that cause fish to jump out of aquariums.

High levels of ammonia, nitrites, and nitrates will cause your fish to become sick. Once a fish senses poor water conditions and starts to become sick, it will do anything it can to escape these conditions and may possibly try to jump to a ‘better world’. Unfortunately, that often does not exist and results in your fish hitting the floor which goes unseen and then dies.

To prevent poor water conditions you must never overfeed your fish and conduct regular partial water changes to help maintain healthy water conditions. You can test your water with test kits like the API Test Kit which is available from Amazon for both Freshwater and Saltwater fish.

2. Lack of oxygen

I have never been suffocated but I can imagine it’s not a nice experience. Well, a lack of oxygen in an aquarium will be just as stressful and life-threatening to your fish.

There are a few signs of low oxygen levels in an aquarium to look out for: Signs like gasping for air at the surface and fish swimming fast and erratic are another. In the later stages of their lives, they will become lethargic and slow-moving.

Thankfully you can quickly restore perfect water conditions and oxygen levels by either introducing oxygen in the form of an air pump. Or, you can add water movement to the surface of the water. We use wavemakers in many of our aquariums to move the surface water around which holds and draws more oxygen down into the aquarium for the fish to breathe.

fish hiding in seaweed
Create safe hiding places for your fish to reduce stress

3. Preditors and stress

We have all seen bigger fish chasing smaller ones around the aquarium and feeling helpless to stop it. But this is one of the main reasons why fish jump out of aquariums.

Most good pets stores will advise you on the right fish and tankmates for your aquarium. However, we all make mistakes and sometimes there is tension within the aquarium between two fish. More often then not it’s the big fish, little fish syndrome.

The poor little fellow will swim like crazy to escape the predators and can be chased up to the surface and often out over the top of the fish tank.

Many new fish, when first introduced, will instantly look for shelter and somewhere to hide. If you don’t provide plenty of caves and hiding places and plants for them to hide in, then they will have nowhere to go. This will cause stress to your new fish and make them behave in an erratic manner.

Then guess what? The fish jump out of the aquarium trying to find a safer and more relaxed home.

How To Prevent Fish From Jumping Out Of The Aquarium

Thankfully there are a number of things you can do to prevent you from losing your fish. Firstly let’s take a look at newcomer fish and how to introduce them. This isn’t an acclimation process but some tips for setting the right environment for adding them.

Simple steps for adding new fish into an aquarium

  1. Turn the lights down low: This has a calming effect on your new fish. Turn not only your aquarium lights off completely when adding new fish but also your home lights. Or at least dim them a little.
  2. Distraction: Distract your current stock of fish by feeding them at the same time you add new fish. They will be far too busy eating to see or pester your new fish. This will allow the newcomers time to find a hiding place to sit and relax until they build up enough confidence to start exploring their new home.
  3. Hiding places: Ensure you have plenty of places for your fish to hide. Plants are a good way to create natural hiding places along with rocks and caves. Having somewhere to disappear to when first added to an aquarium is one of the methods of calming down your stressed new arrival.
  4. Add a lid: By covering your aquarium you can prevent your fish from escaping. Whether this is by accident or through choice. Either way, by adding a suitable cover or lid, you can prevent the untimely death of your fish. For a small cost, you can save a life!

Stop Your Fish Jumping Out Of The Aquarium.

A simple but effective method of preventing your fish from jumping out of the aquarium is to add a cover or lid. There are a number of things to consider when adding a cover to your aquarium.

Metal covers, for instance, can rust and poison the water in your aquarium. Glass covers offer a risk from accidental damage and are especially dangerous if children have access to the lid.

We use specialist metal screens coated with a protective layer to prevent rust and pollution to our aquariums. The trend at the moment is to have natural looking aquascape aquariums with open tops. These allow light to penetrate the surface of the water and also allow the plants to grow out of the water.

With aquarium screens, you can have the best of both worlds. Light will penetrate the water and plants have gaps to grow up through the screen.

You could also have a hood with fitted lights inside. It’s entirely up to you and there is no right or wrong way to prevent your fish from jumping out of the aquarium. As long as you take action and stop them dying.

We use Zilla screens which come in a variety of sizes suitable for most aquariums and are available from Amazon. For larger aquariums (bigger than 48″), you’ll need to get creative and build a framework to fit your aquarium and attach a suitable mesh which could be metal, plastic or even material.

Conclusion: Why Do Fish Jump Out Of Aquariums?

So, let us break this down. Fish jump out of aquariums because they feel the conditions are either not suitable or they are being chased by preditors and fear for their lives.

We hope by writing this article we can prevent the loss of fish life by helping you understand why fish jump out of fish tanks. In the wild, fish obviously jump out of the water for other reasons but thankfully there’s always water nearby for them to land in.