Why Are My Tetras Opening And Closing Mouth?

why are my tetras opening and closing mouth?

Have you ever seen your Tetra fish open and close its mouth before? if you have, you must be wondering why. If you are reading this article, it could only mean that you want to understand why your Tetra is behaving in such a manner, I suggest you read this short article to the end.

Why are my Tetras opening and closing mouths? Fish in general do open and close their mouth to breath when they can’t get enough oxygen in the water.

Fish are not mouth breathers, not even Tetras, so they barely open their mouth and close it, unless they are eating or they are drinking water, but they don’t just open their mouths to breath unless something is wrong.

There are some reasons why the oxygen in a fish tank could deplete which will make them opt for mouth breathing or be acting as if they are yawning, they are:

1. Lack of the necessary aquarium equipment: A Fishtank cannot be complete without having a filter, heater, air stone, or air pump and plants.

These are the necessary things that keep the water from losing oxygen and getting excessively dirty.

The fact is, when the water temperature is very cold, the oxygen in such water will deplete and the creatures in it will suffer a lack of oxygen, so Heater is very necessary because Tetras are tropical fish.

Again to keep the water from getting very dirty and polluted which will breed toxins such as ammonia, Nitrite, etc which will affect the fish gills and prevent them from breathing very fine a filter is highly needed to keep the water clean.

2. Stress: It is very common for Tetras and other fish to be opening and closing their mouths whenever they are Stressed.

Stress could come as a result of many things such as unsuitable tank mates, wrong water parameters, lack of the necessary equipment in the tank, Toxins, etc.

When they are Stressed, they will be breathing heaving with their mouth as if they are forcing themselves to breath.

3. Sometimes they do it to clean their gills: We all know that fish breath through their gills, but sometimes dirty particles will clog in their gills making them unable to breath very effectively.

When this happens, the fish involved will open its mouth, take in water and use it to flush or wash its gills. many fish does this, including Goldfish and Tetras, and that may be the reason you think they are breathing with their mouth.


These are the common reasons why Tetras mouth breath.