In the aquarium, you can see fish darting around the tank due to various reasons. Why do fish dart around the tank? A lot of people ask this question and I thought it was a good idea for sharing on my blog.

The fish will dart around the tank due to various reasons such as fish become stressed, due to lack of oxygen, lack of food, and many more reasons too. You need to provide good care for stressed fish otherwise they will have health issues too.

In this article, we are going to show the 5 various reasons for fish darting around the tank. We have also provided some solutions that I’ll recommend doing. from my experiences. So follow till the end and if you have any questions feel free to comment below

Let’s start.

Why Fish Darting Around the Fish Tank

Fish Darting

The fish will dart around the tank due to various reasons. Sometimes it may be the behavior of fish darting around the fish tank. You need to closely analyze the fish’s behavior in the tank.

Some of the fishes will fight and show some erratic swimming movements. You need to make sure that fish are not fighting or harassing.

In my experience, if you see the fishes fighting and darting around the tank then you need to separate the fishes from those who harass them.

Otherwise, the fish will be stressed which leads to major problems.

What Are the Reasons for Fishes Darting (With Solution)

There is a lot of reason for fishes darting. When I research this topic with a veterinarian, she told me the reasons that I will explain below.


Fish Darting

The fish will dart around the tank due to stress. They may be showing some erratic movement such as swimming upside down, floating on the surface, or gasping for air.

You need to care for the fish and provide a better aquatic environment in the tank. If I find a stressed fish then I will separate the fish into another tank and provide good oxygen content and feed them live food for a while.

The only solution is to separate the fish into another tank and change the water regularly and provide oxygen into the tank. Check the water temperature, Check the pH level.


If your fish tank has so many fishes like a community then it could make many fishes stressed and dart around the tank. The fishes may fight or harass other fishes in the same tank.

So they become stressed, and many beginners will make a fish tank and add so many fishes without knowing any information. Try to avoid aggressive behavior fishes.

The only solution is to separate the aggressive fishes into another tank.

Low Oxygen

Fish Darting

If the fish tank has a low oxygen level, then fish will start darting around the tank. They will start gulping oxygen from the water surface and spending a lot of time on the surface. It was due to cloudy water without any live plants.

You need to add live plants into the fish tank because they can generate more oxygen in the fish tank. Use a good air pump for pumping air into the water.

The only solution for low oxygen is to pour water from height or change the water. The aquarium air pump will also help to maintain the oxygen level in the tank.

Poor Feeding

Poor feeding happens in the majority of tanks. The fish will not get enough food while feeding.

It was due to adding more fishes into a single aquarium, they feel stressed and start attacking other fishes. The beginners have a lot of problems while fish keeping, If you start a fish keeping then you need more tanks for fish.

Don’t make a community tank with a lot of species because some of them are very aggressive and they will eat whole food at first and many small fishes will not get enough food.

You can keep a separate fish tank for various species or feed them on two or three sides and make sure all the fishes get enough food.

Low-Quality Water

Fish Darting

The fishes will dart around the tank and shows some erratic movements due to low-quality water. Fishes will be struggling to breathe inside the tank. Low-quality water will result in sudden explosion of toxic ammonia and bad bacteria in the tank.

You can clean the tank by completely removing the equipment and live plants from the tank. Clean the tank very carefully and pour some water with non-ironized salts into it and keep it for 2 hours.

After that, you can clean the tank and add fresh water to the tank. Before adding fish, you need to check the pH level and temperature.

Do aquarium lights stress fish?

Aquarium fishes don’t need any light to live, you can turn off the light at night when you sleep.

Light is important for live plants for generating oxygen into the water but if you turn on the light for so many hours, the fishes become stressed.

Too much light will encourage the growth of algae in the tank and there will be sudden explosion of algae that leads to a dirty aquarium.

Do water changes stress fish?

A sudden water change will make the fish stressed, you can change the water and check the temperature before adding fish into the tank. You can remove 80% of the water and add fresh water without removing the fish.

Don’t add water without normal water temperature. It was the major reason the many fish keepers makes while changing the water.

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