why does my tetra stay at the bottom of the tank?

Why Does My Tetra Stay at the Bottom of the Tank?

Tetra fish are always a popular choice for aquarium lovers, favoured for their exotic patterns, docile temperament, and general hardiness. I don’t know a single person in this hobby who has not kept tetras. They’re excellent options for beginners and experts alike, but, regardless of your experience, it’s important to understand their behaviour so you can recognise if something isn’t quite right. If your normally lively tetras are spending a lot of time at the bottom of the tank, this could signify something that needs your attention.

Tetra fish can stay at the bottom of the tank due to swim bladder infections, ich, or pregnancy. This behaviour can also signify that your tank isn’t the best environment for your fish. Staying near the bottom of the tank may be a sign that you need to perform a water change or adjust the temperature.

The rest of this article will tell you everything you need to know about bottom-dwelling tetras, so you can better understand what this behavior means and how to address the different problems it can signify.

glowlight tetra
Glowlight Tetras at the bottom of a tank

Why Is My Tetra Fish Lying at the Bottom of the Tank?

Here are some reasons why your tetra fish could be staying at the bottom of the tank:

  • Your fish has a swim bladder infection. Fish have an organ called a swim bladder that controls their buoyancy and ability to swim properly. Unfortunately, swim bladder infections are common. If your fish is swimming strangely, upside down, or unable to swim to the top of the tank, they might be suffering from an infection.
  • Your tetra is suffering from ich or another illness. If your tetra is frequenting the lower section of its tank, this can mean that your fish is sick and needs treatment as soon as possible.
  • The tank needs to be cleaned. A dirty tank can make your fish sick. This is why it’s important to make frequent water changes.
  • Temperature adjustments may need to be made. If your fish is too hot or too cold, it might spend less time being active and more time near the bottom.
  • An aggressive tank-mate has injured your fish. An injured fish might not be able to swim regularly. Your tetra may be taking shelter at the bottom of the tank from another fish who is bullying it.
  • Your tetra is carrying eggs. Tetras often spend time near the bottom of the tank if they’re close to laying their eggs. You will notice just before they lay their eggs they will start swimming around the bottom of the tank in a bit of a crazy manner. Tetras are known as egg scatterers, which means they lay a large number of eggs randomly usually at the bottom of the tank.

Do Pregnant Tetras Stay at the Bottom of the Tank?

Firstly, tetras don’t get pregnant, they carry eggs which are then fertilised during spawning outside of her body. Egg carrying tetras do stay at the bottom of the tank when they are close to spawning. However, they will be very active while they are there. They may even look more active than normal.

But how exactly can you tell if your tetra is carrying eggs or not?

How To Tell if Your Tetra Fish Is Pregnant.

If you think that your tetra may be pregnant, here are some common pregnancy symptoms you should look out for:

  • Your tetra is spending lots of time near the bottom of the tank. Not every tetra is the same, but many display this behaviour during pregnancy. As I mentioned earlier, they won’t be lying there quietly, like you may see with livebearing fish.
  • Your tetra is visibly more prominent than normal. Obesity in fish isn’t exactly a common thing. If you notice that your tetra’s stomach appears to be bigger than usual, this can be a sign that your tetra is carrying eggs. They can scatter hundreds of eggs at a time so will certainly look rounder than normal.
  • Spawning tetras may hide. If you have good hiding places in your tank (as you should), a spawning tetra may want to keep a distance between herself and the other fish around her.
  • Your tetra is female. While this may seem obvious, you must know whether or not your fish is female before making any judgments about pregnancy. This is crucial because if your tetra is a male, it’s likely that your fish is ill as they are not going to be pregnant. This can also signify the need for water adjustments.

This 2 minute YouTube video shows a black neon tetra spawning and then releasing eggs.

Are Tetra Fish Bottom Dwellers?

Tetra fish aren’t bottom dwellers. While they’re known to have the occasional algae snack, they’re not naturally bottom feeders and should be swimming around the entirety of the tank. Bottom-dwelling fish include loaches, corydoras, plecos (plecostomus), and others.

If your tetra is spending a lot of time at the bottom of the tank, this is considered abnormal behaviour.

I have 6 neon tetras in my tank and they spend most of their time swimming around the middle and top of the tank. If they do go to the bottom of the tank, it only seems to be for a minute or two and then they are off again.

blue neon tetras tropical fish
Neon tetras

Signs of Illness To Look Out For.

Unfortunately, a bottom-dwelling tetra might be a sick tetra.

As previously discussed, tetras aren’t natural bottom-dwellers like loaches and other common bottom-feeder species. If you’re convinced that your fish isn’t pregnant, it’s essential to check for symptoms of common fish illnesses.

Here are some illnesses and ailments you should check for:

  • Ich: Ich is one of the most common illnesses seen in freshwater fish. It’s a parasitic infection that causes white spots to appear on your fish.
  • Swim bladder infections: An infected swim bladder can affect your pet’s ability to swim properly.
  • Fin rot: Fin rot is relatively easy to diagnose. While this is more common in bettas and other fish with more elegant tails, mollies can still be prone to this.
  • Poisoning (contaminated water): Unfortunately, it’s all too easy to contaminate the water in your fish tank accidentally. If you use harsh soaps to clean your fish care supplies, the chemicals in the soap can transfer over to your tank. You should also have a designated bucket for water changes to protect your fish from cleaning solutions.
  • Chlorine sickness: It’s imperative to ensure that the water in your fish tank is dechlorinated. If you forget this step during cleaning and/or water changes, this can make your fish very sick.

In addition to bottom-dwelling behaviour, here are some signs of illness that you should look out for:

How To Treat Common Illnesses.

If you think your fish is suffering from an illness, it’s crucial to treat your tank properly. One easy fix is, surprisingly, garlic. Garlic has strong antiparasitic properties for both humans and animals, so it works really well for treating ich. By placing a small piece of garlic in your fish tank, you can quickly rid it of ich and keep your fish healthy.

Garlic is also antibacterial and antifungal, which means that it can help soothe the symptoms of fin rot as well.

Do Tetras Like To Hide?

Tetras like to hide, like most fish. Hiding places allow your tetra to feel safe while getting accustomed to a new tank. They can also serve as shelter, just in case some of the other tank members show aggression.

A problem with an aggressive or bullying tankmate could be a reason why your tetra is staying at the bottom of the tank. They could be stressed out by any aggression so wants to hide away. It would be quite unlikely to be another breed of fish though, as tetras tend to keep to themselves.

If you have other tetras in your tank, there may be a dispute over the pecking order. This would only really happen if you already have an established group of tetras and have recently added some new tetras into the tank.

If your fish stays close to the bottom to hide, this is probably nothing to worry about. It’s still a good idea to double-check for symptoms of pregnancy and illness for safety.

emperor tetra
Gorgeous colour!

Final Thoughts.

Tetras are classic fishkeeping favourites because they’re relatively easy to care for. However, no fish is immune to ailments. If your tetra is spending a lot of time near the substrate, this can mean illness, pregnancy, or an inadequate environment.

Hopefully, this article has helped you better understand your tetras, so you can analyse their behaviour and continue to keep your fish as happy and healthy as possible.

More Tetra Related Articles:

Will different types of tetra school together?

How many tetras can I safely put in a tank?