When someone mentions a pet fish, one of the first associations that come to our minds are certainly goldfish. Indeed, these amazing little creatures have been among the most common aquatic pets for many years now.

They can cause various concerns among their human keepers pretty often. Have you ever noticed your favorite pet constantly opening its mouth for a while? Well, you are not alone.

This happens quite commonly actually, and sometimes for harmless reasons. Other times, however, you will have to intervene, so it is good to know how to distinguish the various causes.

Goldfish Opening and Closing Mouth

So, here are the most common reasons why goldfish are constantly opening their mouth:

– Normal Behavior

Before we even begin describing the possible negative scenarios, let us be clear about one thing: fish opening their mouth is, most of the times, a completely natural and normal behavior.

So, unless you are not sure about your water parameters or the environment that your fish is surrounded by, there is absolutely nothing to worry about.

Goldfish breathe through their gills. And such gills sometimes get slightly obstructed by food residues or similar debris, so they occasionally have to rinse them off.

And the only way to do that is by opening and closing their mouth for several times in a row. This does not mean that your fish are in any kind of danger, but rather performing some occasional maintenance.

– Asking for Food

Goldfish are fairly intelligent creatures that can interact with their human keepers once they start feeling comfortable around them. Therefore, if you recently have not fed your pet, it may be simply asking for food.

If there are no visible distress indications and the testing water kit shows normal values, your fish may be hungry. However, that does not have to mean that you need to provide them food whenever they are asking for it.

Overfeeding may soon become a huge problem not just for the fish which eats too much, but also for the other fish which live in that tank, as ammonia may spike quickly enough.

You should always follow a consistent feeding schedule in order to provide your pets the right nutrients in apposite quantities.

– Lack of Oxygen

If you notice your goldfish opening its mouth in a quick pace, it probably means there is an issue with water oxygenation.

In fact, when there is not enough oxygen for them to breathe, they will try absorbing some more by opening their gills in a faster rhythm. Also, your pet may stick to the tank top during such conditions, panicky gasping for air.

Sadly, goldfish are often sold at local fairs or even pet stores in simple glass bowls. This is obviously not an appropriate home for any fish, but many inexperienced owners are unaware of that, and often end up accidentally suffocating their fish. Other common situations include overstocked tanks or non-filtered tanks.

You should provide your pets with the right levels of oxygenation. This can be obtained with a proper filtration system, regular partial water changes, or apposite aeration devices such as air stones.

– Poor Water Quality

Intricately connected to a lack of oxygen, poor water quality also leads to your pets suffocating. And, while they do, they will obviously be gasping for air.

All fish produce waste during their daily routine, but it is up to their humans to maintain their water pristine clean. Otherwise, such waste will soon lead to increased levels of ammonia and nitrites, which can be extremely dangerous.

The only way to be sure of your water quality is to regularly test it. Along with that, you should perform partial water changes every now and then, as well as have a filter.

– Stress or Disease

Stressed fish breathe more rapidly, and that is a fact. Therefore, if you have ruled all of the previous reasons out and you are still not sure what is causing your pets breathing in such way, try checking their environment out.

Perhaps your goldfish have now grown to a fair size and they feel cramped around their too small tank, or you have accidentally added too many fish to their community. Wrong pH levels, inappropriate food and travel may all be serious stress triggers.

Alternatively, your beloved pet may be suffering from a disease which affects its gills and blocks normal breathing possibilities. In that case, you should be able to notice other indications such as visible redness or any other obstruction across its gills, a lack of appetite, an odd behavior.

– High Temperature

Too warm water may block the oxygenation process and suffocate your goldfish, forcing them to desperately gasp for air. This is quite easy to confirm, as the only thing you have to do is to check your thermometer. 

You should regularly keep track of your water temperature levels and adjust the heater accordingly.

– Aggressive Tank Mates

If your beloved pets are being bullied by some aggressive tank mates, this will cause serious stress and compromise their wellbeing. This is intricately linked to general stress disorders.

How to Keep Your Goldfish Happy?

Keeping your goldfish happy is not a difficult task, but it is neither that simple as placing them into a bowl and leaving them onto your desk. Here are some simple guidance points which you can apply:

  • Goldfish require a decently sized tank just as any other fish does. Depending on the sub-species, a general starting size is 20 gallons.
  • Once you find an ideal tank, you should now set it up properly, including a filter and a heater. And remember to get a high-quality thermometer as well as simple testing kits.
  • Make sure to regularly clean their home by performing partial water changes and by constantly testing the water parameters.
  • Feed your fish with appositely designed food and avoid overfeeding them at all times.
  • Monitor your pet’s behavior to ensure they are not suffering from stress or diseases.

Wrapping Up

Goldfish cannot talk, but they certainly can show signs of distress.

Therefore, asking yourself why your pet keeps opening its mouth is a great sign of responsibility, and such behavior should always be observed to rule out the possible complications it may lead to.

Written by Fabian

Hey, I'm Fabian, chief editor at Aquarium Nexus. I really enjoy the aquarium hobby and love sharing my experience with others. If you have any questions feel free to contact me or leave a comment below.

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