Why Does My Tetra Fish Stay in One Spot?

Why Does My Tetra Fish Stay in One Spot?

Does your tetra always seem to stay in the same spot? You’re not alone! Many fish tend to stay still, but there are a few reasons why.

This behavior can be due to several things, but it’s usually a sign that something is wrong.

In this post, we’ll explore why your fish might be sticking to one spot and what you can do about it.

Why Does My Tetra Fish Stay in The Same Spot?

Water quality

Water for fish is like air for humans; if the water is poor or unclean, fish will not survive.

Insufficient water isn’t always obvious, and if your water is crystal clear, it doesn’t imply that your fish tank water is good; dissolved poisonous gases may be present in the tank water, which can harm your fish, and you don’t know!

So, to keep the water clean, you’ll need a water filter that combines both mechanical and biological filters.

These filters remove physical debris and decaying matter from the water while promoting the growth of beneficial bacteria that help to break down ammonia.

The most straightforward approach to assure that the water is safe is to conduct routine “water testing” using a “water testing kit” and monitoring levels of dissolved toxic gases.

This kit will help you monitor the water’s quality and make the necessary changes to ensure that your fish have a long, happy, and healthy life.

Water temperature

The wrong water temperature causes the fish to become stressed, causing it to remain still and motionless. Your fish will find their ideal temperature comfort zone and stay there.

This can happen for one of two reasons: either you don’t have a heater, or you have the incorrect heater for your tank.

If you have a low capacity heater, temperature pockets will develop in such situations, and certain fish will attempt to sit in the most suitable locations without moving much.

So, if you think that your water heater isn’t enough to heat the entire water capacity, check the temperature of the water in various locations of the tank and reasonably determine if your heater capacity is adequate or not.

However, if you don’t have any heaters, we recommend purchasing one as soon as possible because your fish will eventually perish without them.


Tankmates play a significant role in fish health.

Bullying is a severe problem in the fish world, and bigger fish are known to assault and even murder tiny or recently introduced fish.

Before acquiring new fish pairs, you should research “fish compatibility” to avoid such catastrophes.

The new fish must successfully cohabit with the old species and enjoy social interactions. If not, there will be duels.

To avoid such disputes, fish will frequently congregate in the corner of the tank due to stress.


When fish are unwell, the disease reduces their energy for moving and enjoying, making them more inclined to stay in one spot.

If you discover that a fish has strange behavior or spots on its body, it may be unwell because of an illness.

In such cases, it is always better to move your fish to a quarantine tank and treat them there.

Never treat your sick fish in the same tank as other normal and healthy fish swimming around.

This is because medications added to the tank can have adverse effects on water chemistry, which can be harmful to other healthy fish.

Some medications even have a side effect of decreasing dissolved oxygen levels.

If this happens, you’ll see your fish gasping for air at the top surface of the water.


Fish tend to sleep when there is dark outside. In the natural world, sunlight is the main source of natural light, but in a tank, you simply use artificial light.

So, to help your fish sleep, we recommend switching off the lights in the room where the tank is located; this will replicate natural light and dark conditions.

If you have a bright light over the tank, we also suggest using a “light timer” to turn it off automatically at night. This will help your fish relax and have a good night.

Fish tend to sleep with their eyes open and stay in one spot. This condition should not be confused with other conditions when fish remain in one place even during bright daylight conditions.

Fish tank environment

There are many things that are responsible for creating a healthy environment for fish.

If you newly introduced a fish in your tank and you find that it is staying at one spot, wait for some time to get it adjusted to the water quality, temperature, eating habits, and tank mates.

As your fish gains confidence, it will start moving around and exploring things independently.

Fish bought from pet stores are generally under tremendous stress because of constant human movement around the tank in the pet stores. Many times kids who see the fish in the tank start poking their fingers in the water or making loud noises, and even such a simple act can produce stress.

When that fish moves to your new tank, it will take some time to explore things and adjust to the new environment.

Amount of Dissolved oxygen

When your tank has less amount of dissolved oxygen, fish will gasp for air at the top of the tank.

If your fish is staying at one spot near the water surface, it is probably getting a good amount of oxygen that it can’t get at the bottom of the tank.

Fish breathe oxygen that gets dissolved in the tank water, and this exchange of gases happens at the top of the water surface.

Many tanks have air pumps installed out of the tank to encourage this gas exchange.

This pump pushed fresh air into the tank water through a tube. The air escapes through an air stone and moves upwards, creating a spectacular air bubble because of the air stone.

When these air bubbles reach the water surface, it gets agitated because their area increases, where oxygen gets mixed in the fish tank water.

If enough area is not agitated, the tank will have less oxygen entering the water through the surface exchange, and fish will gasp for air at the top of the tank or stay at one spot to get enough oxygen right at the top surface.

To avoid such situations, check your air pump’s compatibility and whether it is sufficient to agitate enough water to exchange beneficial gases easily.

Many tanks use powerheads or wavemakers to agitate water surfaces for oxygen exchange, which works best for larger tanks.

Some fish tank owners avoid using air pumps because they produce a humming sound in the tank’s room.


If a female fish is pregnant, it will probably stay behind decorations or plants to find a safe spot to lay eggs and protect herself from attacks.

In such cases, learn to identify a pregnant fish and move her to a quarantine tank to avoid accidents.

Apart from staying in one spot, fish display many fish behaviors when under stress. All kinds of stress lead to diseases and, if not treated, can cause death as well.

It is always better to keep the fish in a quarantine tank when you buy them from a pet store and observe behavior in this hospital tank for at least 15 days.

This approach will help you understand your fish’s natural behavior and observe any early signs of stress or disease.

A healthy fish is always active and has a good appetite.

Last Words

If your fish stays at one spot, you first need to observe the fish and look for any other physical changes.

Check if it’s eating properly and has a good appetite.

If everything looks okay and there are no other physical changes, give some time for your fish to get adjusted to the new environment.

We hope you enjoyed reading this article and it was helpful to you.

If you have any questions or suggestions, please feel free to leave a comment below.