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Do Fish Yawn?

With a huge number of people recently getting involved in fish keeping, we have noticed a spike in the number of questions from the community about keeping fish.

The more commonly asked questions are usually relating to keeping your pet fish in the best possible health but we have also noticed some more unique questions that have a surprisingly large number of people asking about them.

One of these questions that we have noticed a large number of people asking about each month is “do fish yawn?” and we can understand why so many people reach out to ask this.

The natural gulping movements of the majority of fish species can sometimes make it look like the fish is trying to yawn at times and if they slow this movement right down then it really can look like they are yawning.

Due to fish breathing with their gills rather than their mouths, this movement of the fishes jaws can easily spike some curiosity in fish keepers who observe their fish close enough to notice this movement.

In turn, that they results in a large number of people reaching out about if fish yawn or not too in an attempt to satisfy their curiosity on what is actually happening.

Do Fish Yawn?

Fish do not yawn due to breathing via their gills rather than their mouths so there is no need to yawn to increase the oxygen level in their blood when their breathing rate slows.

The movement that fish make with their jaws that looks similar to yawning is usually to attract a mate or to deter a potential predator from attacking them.

This is why the behaviour is more common in aquariums with multiple fish in them due to seeing the other fish as potential mates of potential threads to them.

This increases how frequently your fish will display this “yawning” motion with their jaw and can result in some fish keepers presuming that their pet fish are yawning in their tanks.

As we just touched on, this is not actual yawning in the same what that a human would yawn so there is no need to worry about any potential health problems with your fish or the oxygen levels in the water.

Every now and then, we do see a worries fish keeper asking if the yawning motion is anything to worry about with their fish and the majority of the time it’s not.

That said, you should keep a close eye on any smaller fish in larger tanks with a large number of fish as it may be being bullied by other fish in the tank and its yawning motion may be it trying to prevent other fish from attacking it.

But I Saw My Fish Yawn!

We know that some fish species will make a movement with their jaw that makes it look like they are yawning and if the fish is relaxed and does the movement slowly, then it can look as if your pet fish is yawning.

Due to fish breathing via their gills and not their mouth, there is no need for a fish to yawn and the movement with their mouth is probably just your fish trying to attract a mate.

Humans tend to yawn due to their breathing rate subconsciously lowering due to being relaxed, often when we are tired or relaxing.

We yawn as a way to force a deep breath and drastically increase the amount of oxygen that we have in our blood for a short period of time to help wake us up.

The yawning motion in a fish does not serve this purpose as they take water in via their mouth to filter for food rather than to take in oxygen.

Fish breathe via their gills so any need for a spike in oxygen in their blood flow will be apparent in rapid gill movement rather than a mouth movement.

Why Is My Fish Opening Its Mouth?

The majority of the yawning motion that fish make is to either attract a potential mate or to try and deter what they perceive as a threat.

Some type of fish will also make this movement to take in water to filter for food and can be more common if you live feed the fish in your tank.

When eating, the yawning motion is more common when trying to take in any live daphnia that you have added to your tank due to the water flees being small and easy to miss if they don’t take in a large amount of water.

The majority of fish species tend to really enjoy chasing live daphnia around their tank so it can encourage the jaw movement that makes your pet fish look like it is yawning.

In addition to that, larger fish can also display a similar movement with their jaws that make them look like they are yawning when you live feed them brine shrimp too due to their small size.

Some fish species will use this jaw motion as a part of their mating ritual with it often being a way to try and attract a mate.

In this case, it is usually the male of the species that will exhibit this behavior and they will usually still move their jaw in this way even if there are no female fish in the tank with them.

A number of fish will also move their jaw in a way that makes them appear to be yawning if they feel threatened and are trying to scare off other fish too.

Should I Be Worried If My Fish Looks Like It Is Yawning?

Although some people do get worried if it looks like their pet fish is yawning due to thinking it means that there is a lack of oxygen in the water in their tank, it is usually nothing to worry about.

Fish don’t use the yawning motion when breathing due to fish using their gills for oxygen rather than their mouth so it usually has nothing to do with their ability to breathe.

As we touched on earlier in the article, the majority of fish will use the motion that makes it appear as if they are yawning to attract a mate or to deter a predator.

One thing that you are able to use as an indicator of any potential issues is to watch all of the fish in the tank to see if they are all making the yawning motion with their jaw on a regular basis.

Even then though, this does not necessarily mean that you should be worried if you notice that all of the fish in your tank are making this motion. If you live feed your fish then they could just be using the motion to catch the food that you have added to your tank and there is no need to worry.


That brings our article going over if fish yawn to an end. As we have mentioned, fish do not yawn as they breathe through their gills rather than their mouth so they have no need to yawn. They do have a number of behaviours that will require the fish to move its mouth in a motion that makes it look like its yawning but these behaviour are not related to the breathing behaviour of your pet fish in anyway.