A fish attempting the jump out of its tank is not normal and is an indication that something is not quite right in its environment. A happy fish will not try to flee the environment. Determining the cause is the first step in figuring out why your fish are jumping from their aquarium. Keep in mind, there are a variety of reasons for this behavior.

We will be informing you of every possible reason your fish may be jumping out of the tank as well as few methods to deter this behavior.divider1- goldfish

6 Reasons Fish Jump Out of Their Tank

It is shocking to come home to find your favorite fish in a puddle on the floor. Alive if you find it early or deceased if you are too late to the scene. Here are the answers to why your fish is displaying this unwanted behavior-

1. The Tank is Too Small

goldfish in a bowl

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Fish appreciate a great deal of space. When confined to a small and cramped space, the fish will attempt to flee its living conditions by jumping out from the tank. A fish should be given as much space as you can afford and keep. Fish become uncomfortable when there is no room to swim appropriately.

2. Poor Water Conditions

dirty water

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Exposing your fish to poor water conditions with high ammonia, nitrites, and nitrates, the fish will escape these conditions as it has nowhere else to go. If the water is polluted from toxic decorations that leak chemicals into the water, or even cloudiness from unwashed gravel will cause enough distress for your fish to jump out of its tank.

Too acidic or alkaline water can harm a fish, if the right pH balance is not maintained, the acidity of the water will begin to burn the fish.

3. Undesirable Temperature


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Fish are sensitive to temperatures. This includes both fluctuations and unsuitable stable temperatures for the species of fish you keep.

Cold and temperate water fish need to stay in a range between 18ºC to 23ºC. Whereas tropical fish need a stable temperature between 22ºC to 28ºC before the water becomes unbearable.

If the tank’s water fluctuates regularly or the fish is in its incorrect temperature preference, it will jump out of the tank.

4. Aggressive Tank Mate

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Some species of fish are territorial and do not get along with other fish. Keeping a fish that is unsuitable for community tanks will lead to fights, fin nipping, and aggressive chasing which will leave your submissive fish no choice but to flee the tank from the tankmate.

5. Stress

goldfish and guppy in tank

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Fish that are kept in a stressful environment with a variety of stress triggers will feel overwhelmed and escape out of the tank. Constant light changing distress, bright lighting over the tank, poor lighting for some time, noise and constantly moving the tank will cause the fish to become stressed.

6. Fright

woman playing with pet goldfish

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By tapping the glass of the tank, knocking or rough handling will cause the fish to jump out of the tank due to fright. A fish that is suddenly scared will instinctively jump out of the tank, mostly due to reflex.goldfish divider

How to Stop a Fish from Jumping Out the Tank

  • Keep your fish in a spacious tank with lots of swim room both vertically and horizontally.
  • Keep an air stone and filter in the tank to ensure the water stays clean. Rinse all-new gravel as it is dusty and regularly test the water for unsuitable parameters.
  • Do not tap on the glass or place the tank in a noisy and chaotic environment.
  • Purchase a secure aquarium lid to fit your tank’s design.
  • Keep the right species of fight together to avoid your fish from jumping in an attempt to flee from its tankmates.
  • Always cycle a tank before placing fish into it (the nitrogen cycle).



Ensuring you meet your fish’s needs and special requirements, your fish will remain happy enough to stay inside its tank. Regularly check the water parameters and research the best temperature and pH to keep your fish in.

Although a lid seems like a pretty easy solution, for the overall benefit of the fish, the cause should be addressed first.

Featured image credit: Mikael Damkier, Shutterstock