Axolotl Open Mouth or Yawning? What Is Gaping and When To Worry?

Axolotl Open Mouth

Axolotls keep their mouth slightly open like a small smile. However, if you notice axolotl open mouth as a consistent behavior, it can be a sign of a problem that needs looking into.

In this article, we are looking at when axolotl open mouth is normal and when to worry. In addition, we are recommending how to treat this when it’s a symptom of a health issue.

Axolotl Open Mouth Behavior – Causes

Axolotl open mouth is completely normal in the following situations:

  • Going to the surface to take a gulp of air
  • Yawning
  • Birth defect
  • During deeding or when digesting their food

On the other hand, axolotl open mouth can be a symptom of a health problem such as:

  • Impaction
  • Stress induced by poor water conditions such as water temperature, water hardness, ammonia and nitrate spike or lack of oxygen
  • Improper nutrition

Let’s take a look at these causes in a bit more details.

They Are Just Yawning

axolotl open mouth

Axolotl open mouth can be normal behavior in some situations such as yawning. Yes, axolotls yawn! Normally, when they do this, they also tend to flip their gills back and forth.

The reason axolotls yawn is slightly different than in humans. Axolotls yawn when they’ve had too much food. If they feel the food starting to come back out, they will “yawn” keep it down. It’s almost like they are about to be sick but yawn to prevent it.

Birth Defect

If your axolotl is born with a certain birth defect, they might have their mouth open. Normally, this is the result of inbreeding. As long as your axolotl is acting normal, eating fine and their water perimeters are fine, the open mouth can be down to a birth defect.

Feeding and Digesting

Axolotl open mouth sometimes looks like a smile. Normally, they will “smile” with their mouth open before, after or during feeding. This is how they are swallowing or digesting their food. That’s totally normal and nothing to worry about.

In addition, axolotls will also open their mouth as a stretching technique before eating their food. This helps them loosen up to fit as much as they can fit in one go.


If the axolotl open mouth behavior is something new and persisting, it’s likely to be because your axolotl is impacted.

Axolotls tend to try and eat anything that can fit in their mouth. That’s why picking safe decorations for their tank is essential.

Impaction can be caused by your axolotl swallowing any of the following:

  • Pebbles
  • Snails
  • Gravel
  • Sand

If your axolotl’s mouth is permanently gaping or continuously opening and closing, it can be because they are trying to dislodge whatever is stuck in their digestive track.

Impaction – Symptoms

To be sure that your axolotl open mouth is the result of an impaction, you must check for other relevant symptoms such as:

  • Lack of stool
  • Bloating. Monitor the belly to see if the size has changed. Normally, bloat is obvious to the naked eye. To read the full guide on bloating, head over here Axolotl Bloated Belly? Causes And Treatment For Bloated Axolotl
  • Lack of appetite. This can be either reduced appetite, no appetite at all or the axolotl trying to eat the food but then spitting it back up

Impaction – Treatment

Once you have determined that your axolotl open mouth problem is caused by impaction, you have two options for treatment – fridging or surgery. If fridging doesn’t help resolve the issue, you’ll have to take your axolotl to the vet for a surgery.

Fridging Process

Follow these steps for successful fridging process:

  1. Place your axolotl in a small tub of dechlorinated water
  2. Make sure the axolotl is fully submerged
  3. The water in the tub should be a few degrees cooler than the water in the tank but not as cold as the fridge
  4. The fridge should be around 41°F but no more than 46.4°F
  5. Once the axolotl has acclimatised to the water temperature in the tub (which should be in a few hours’ time), it’s time to put the tub in the fridge.This will help them become accustomed to the cooler temperatures without causing too much stress
  6. The tub would also require daily water changes, using already cooled dechlorinated water. The water used for the change should be kept in the fridge so that temperature shock does not occur.
  7. Avoid feeding them during the process. They will have reduced appetite at these cooler temperatures if they did not already from the impaction
  8. Fridge your axolotl for 5-7 days
  9. When you take your axolotl out, gradually increase the temperature up to what they are used to before placing them back in the tank
  10.  Make sure the tank water has been fully cycled and tested multiple times

To read the full guide on constipation and impaction in axolotls, head over here Constipated Axolotl? What Causes It and How To Treat

Poor Water Conditions

Axolotl open mouth behavior can be the result of poor water conditions such as:

  • Water temperature too high
  • Lack of oxygen
  • Spike in ammonia or nitrate
  • Water hardness

Water Temperature Is Too High

If the tank water temperature is too warm, it can cause various health problems for your axolotl.

Axolotl open mouth can be a sign of stress and discomfort triggered by the water being too warm.

How To Fix It?

The ideal water temperature should be kept at 60° F – 64 ° F. It’s also as important to ensure that the temperature doesn’t fluctuate and stays the same throughout the day and night.

Possible causes for the water temperature raising too high include:

  • The tank’s location exposed to direct sunlight
  • The tank is near an electronic device such as TV, PC, laptop, etc

If any of the above apply to your situation, you should immediately fix it. Furthermore, if you haven’t already, you should provide plenty of places to hide for your axolotl such as a little cave like the one below.

A quick way to decrease temperature is to place frozen water bottles in the tank and keep replacing them once they melt. It’s essential to keep checking the temperature whilst doing this as it’s essential to maintain the same temperature and avoid fluctuations.

Lack Of Oxygen

As axolotls normally breathe using their gills and lungs, they can be seen gulping closer to the surface. Although, this is totally normal, if the axolotl open mouth is constant, it can be a sign of a problem. This can be caused by the lack of oxygen in the tank.

The ideal oxygen saturation in your axolotl’s tank should be in the range of 70-100. You can test the water oxygen levels by using the kit below.

How To Fix It?

If the oxygen levels are too low, you can increase them by:

  • Adding air stones
  • Air bubbler
  • Use your filter outflow to break the water surface

Spike In Ammonia or Nitrate

Spike in the ammonia or nitrate levels in the tank water can cause stress and discomfort for your axolotl. If that is the case, you might observe your axolotl mouth either being constantly open or continuously opening and closing.

So, what are the perfect levels for ammonia and nitrate? The ammonia and nitrate levels should be 0.

To test the water, you can use the kit listed below

How To Fix It?

To lower the ammonia levels, you need the following:

  • Good filter
  • Regular water changes
  • Cleaning up any leftover food immediately after feeding

To lower nitrate levels, you need the following:

  • Test your tap water for nitrates to ensure it’s not contributing to the issue
  • Water changes are the quickest and most effective way of lowering the nitrate levels
  • Add ghost shrimp to the tank. However, they might not last long as axolotls love to snack on them
  • Continue testing the water daily

Water Hardness

Axolotls should be kept in slightly hard water. If the water hardness is not right, it can make your axolotl stressed and subsequently you might observe them opening their mouth more than normal. Soft water can result in axolotl open mouth behavior as a result of stress and anaemia.

The ideal water hardness for your axolotl tank is:

  • KH should be 3-8deg (53-143ppm). KH is the amount of carbonates and bicarbonates in water
  • GH should be 7-14deg (125-250ppm). GH is the general hardness which measures the hard minerals in the water

You can test the water hardness using the kit below

How To Fix It?

To fix the water hardness, you can simply add salts to the water such as the ones below

Improper Nutrition

If you’re not feeding your axolotl a nutritious diet, it will cause them stress and discomfort. As a result of the stress induced by improper nutrition, you might observe your axolotl keeping their mouth open.

Don’t feed your axolotl only blood worms as they are not nutritious and are more like junk food. Another bad choice is brine shrimp which should only be fed to hatchling.

How To Fix It?

You need to ensure that you’re feeding your axolotl a nutritious diet such as earth worms or pellets nightcrawlers, red wigglers, etfc. Feeding them the correct diet will prevent stress related health problems for your axolotl.

Final Thoughts

Normally, the condition axolotl open mouth is triggered by stress and discomfort from impaction, improper nutrition, or poor water conditions.

On the other hand, your axolotl opening their mouth can be normal behavior in the following situations:

  • During, before or after feeding
  • Going to the service to get a few gulps of air
  • It’s result of a birth defect

If you’re worried about your axolotl’s open mouth behaviour, it’s important to first test the water perimeters and also check for other symptoms by answering the following questions:

  • Are they eating?
  • Is there stool?
  • Are they acting like their usual self?
  • Any changes in their appearance?

Always take into consideration all present symptoms before treatment. If the recommended steps in this article haven’t helped your axolotl and you’re still worried, you should take them to a specialised vet.

Frequently Asked Questions FAQ

Why Is My Axolotl Thrashing and Swimming Franticly?

If your axolotl is thrashing around or swimming franticly, it means something is causing them stress. Possible stressors in this situation include:

  • Water temperature too high
  • Ammonia or nitrate levels are too high
  • Injury

The first thing to do is to test your water parameters and go from there.

To find out about all the possible causes and solutions to your axolotl thrashing, head over here Axolotl Thrashing And Frantic Swimming? When To Worry

Is Axolotl Bumpy Skin A Cause Of Concern?

Axolotl bumpy skin can be a sign of a health problem. When axolotls develop lesions, bumps and lumps on their skin, it means that something in their environment isn’t right. This can be anything from poor water conditions to incorrect diet.

The first thing to do if your axolotl has developed skin problems is to check their water parameters.

To find out more about axolotl bumpy skin, head over here Axolotl Bumpy Skin – Bumps, Lumps, Warts, Lesions? When To Worry?



My name is Iliyana and I'm a passionate animal lover and pet owner. As there is significantly less information online about unusual and exotic pets, I decided to found this website and recruit expert writers to help pet owners.

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