Why Do Fish Jump Out Of The Tank?

As a fish owner you may have witnessed a fish jumping up out out of the water, but why do fish jump out of the tank?

Out in the wild, a fish would jump out of the water to escape something such as a predator. The problem with fish jumping out of the tank in a home aquarium is that they will land on the floor.

If this happens when you are not around then the fish are not going to survive long being out of the water. So why do fish jump out of the tank and what can you do to prevent it happening? All of out tips and tricks will be revealed.

Why Do Fish Jump Out Of Water?

Why Do Fish Jump Out Of Water

Let’s first take a look at the reasons why fish jump out of the tank before we give you some solutions on how you can prevent it from happening.

1. Dirty Water (Too Much Ammonia and Nitrites)

If the quality of the water declines, this will cause your fish to jump out of the water in an attempt to search for a cleaner home. Bad water conditions can be caused by elevated levels of nitrates, nitrites, and ammonia.

Even small amounts of ammonia in the water can make fish sick and potentially kill them. As this is such a major problem, one of the first things you should do is to test for nitrites and ammonia if your fish have started to jump out of the water.

There is no such thing as a safe level of ammonia as even the slightest amount should be a cause for concern. High levels of ammonia are caused by the following:

  • Decaying matter such as fish waste
  • Uneaten food
  • Decaying plants
  • Dead fish
  • Insufficient filtration

So the solutions to eliminate any ammonia getting into the tank are:

You can also read our full guide on how to clean an aquarium here.

2. Lack Of Hiding Places & Space

Your fish may be jumping out of the water due to a small tank being too cramped up with no hiding places or anywhere to escape.

If there are too many fish or too many fish types in the tank, it’s inevitable that they are going to chase each other. The lack of room and available hiding places is going to cause stress on your fish with no where left to go other than jump out of the water.

Always make sure you have the correct size aquarium, as well as providing plenty of plants and caves for your fish to hide.

3. Not Enough Oxygen

If there is a lack of dissolved oxygen, this will cause your fish to jump out of the tank as they seek to find a new home.

Although fish do not breath gaseous oxygen as they do not have lungs, they do require dissolved oxygen which enables them to breath in the water. Here are some of the reasons there may not be enough dissolved oxygen in the tank:

  • Too many fish: If there are too many fish cramped up in a small tank, there will not be enough oxygen in the water. The solutions to this are either purchase a bigger tank, or have less fish in the same tank. Another solution is to add an air stone to oxygenate and aerate the water which provides more oxygen.
  • Algae: Too much algae can be problematic because it can use up a fair amount of oxygen in the tank. Always ensure you remove algae from your tank to enable your fish to breathe.

4. Water Temperature

Another factor in the condition of your water that may be causing your fish to jump out of the tank is the temperature of the water. Fish can be very sensitive when it comes to changes in the temperature of the water.

The water being too hot or cold could cause them to jump out as they search for water with a better temperature. As well as the water itself, the following are also factors that can effect the temperature of the water:

  • Tank located next to a door or window
  • Tank in direct sunlight part of the day
  • Lighting that produces heat
  • Faulty heater

The correct temperature of the water varies, with each type of fish having their own preference. They will generally fall into one of the following categories:

  • Cold Water Fish: Below 68°F (20°C)
  • Tropical Fish: 75-80°F (24-27°C)
  • Temperate Fish: A wide range of temperatures overlapping from the above two categories.

5. Fish Is Hungry

Fish should be fed their required meals on a daily basis to prevent them from jumping out to seek food for themselves. Floating plants should also be kept in the aquarium to enable your fish to eat when they get hungry.

6. Accident

A fish jumping out of the tank could also be an accident. As it happens in all forms of life, your fish may have exited the water due to it swimming too fast and too close to the surface.

How Do I Stop My Fish From Jumping Out Of Tank?

A couple of these points have already been covered, but just to recap and add a few additional tips, here’s how you can stop a fish from jumping out of the tank.

  • Suitable Water Conditions: Always make sure that the water is the correct temperature, as well as being clean and free of nitrates, nitrites, and ammonia.
  • Distract New Fish: If you are adding new fish into the tank, distract your current stock of fish by feeding them at the same time to prevent them from pestering the new fish.
  • Hiding Places: Rocks, caves, and plants should be added to the tank to give your fish plenty of hiding places to retreat to.
  • Add A Lid: Adding a suitable lid or cover to your aquarium will prevent your fish from jumping out of the water. There are many different options available depending on what tank you have, as well Zilla Screens which work great.
  • Compatible Tank Mates: It’s important to know which species of fish are going to be compatible. Pairing the wrong type of fish together can cause them to fight each other over territory.
  • Limit Noise: If your tank is located in a noisy area of your home, it may cause stress on your fish and cause them to jump out. Always place the aquarium setup in a quiet location.

Do Newly Added Fish Jump Out Of Aquariums?

The most vulnerable time for a fish is when they are first added to an aquarium. They are wary of their new tank mates and vice versa which can cause a state of shock. This confusion can scare them and make them jump out of the water to escape.

Which Aquarium Fish Jump Out Of The Water?

Studies have found that certain species of fish are more prone to jumping out of the water. One of these species were Guppies who were found to be jumping out of the water not because or food or to evade predators, but to look for fresh water.

A published paper on the study of guppies can be read here

Another example is betta fish who’s natural environment is shallow water and swamps in parts of Malaysia, Vietnam, Cambodia, and Thailand. The jumping originates from their natural environment where beta fish had to jump as the shallow water dries up.

Due to this behavior, a breathing organ called a labyrinth was evolved over time which enables them to breath for shorts periods of time outside of the water.


The next time you see your fish springing up out of the water, not only do you now know why but you should also be armed with all of the tips and tricks to prevent it from happening.