Do Fish Die of Old Age? The Signs of an Aging Fish

Some aquarium fish are quite expensive to buy, so when you splash your hard-earned cash on a pet fish, you want to know how long the creature is likely to live.

But do fish die of old age, or is some health issue more likely to see a fish off before it reaches its natural life expectancy?

Well, yes, many fish do die of old age, provided they are given the optimum care and an appropriate environment to live in.

However, most aquarium fish die from disease or health problems related to poor water conditions, incorrect diet, or injuries caused by tank mates or aquatic predators.

To learn more, read this helpful guide on the likelihood of your fishy friend dying of old age and much more!

How Long Do Fish Live?

As you can see in the following examples, the average lifespan of fish varies significantly, depending on the species.

That said, it’s important to note that these are just general guidelines, and factors such as water quality, diet, genetics, and the overall care the fish receives can all influence the lifespan of an individual fish.


There are around 200 different varieties of goldfish, all of which have an average lifespan of between 10 and 20 years.

I once had two Fantail Fancy goldfish that survived for around 12 years until they finally died of what was apparently old age.

However, there are always exceptions to every rule, and the goldfish that holds the current world record for longevity is held by a fish called Tish that was won by a family at a funfair in 1956. Tish died at the ripe old age of 43!

Betta Fish

Can Betta fish Die of Old Age

In contrast, the ever-popular betta fish usually lives between two and three years, although some can survive longer if given the proper care.


Fancy Guppies

Guppies are a perennial favorite among aquarists and are well-known for their flamboyant colors and prolific breeding habits.

These beautiful little livebearers constantly produce dozens of young, which is just as well, considering their average lifespan is only one to three years!


Types of Koi

Koi are beautiful pond fish that are popular around the world, gracing many ornamental garden ponds.

These brightly-colored coldwater fish are known for their longevity, typically surviving for several decades, with some reaching ages of 50 years or more, so yes these fish die of old age.


can clownfish live alone

Clownfish were made famous by the film “Finding Nemo” in which one of these beautiful marine fish played a starring role. Consequently, every kid who went to the movies to see Finding Nemo wanted a Clown Fish!

Clownfish have an average lifespan of six to 10 years, but they have been known to live up to 20 years in well-maintained aquariums.

It’s just as well that these little movie stars have a pretty good life expectancy, considering that you can pay around $25 for one of the more common varieties and up to $1,500 for a rare species!

Do Fish Die of Old Age?

Generally if fish die of old age it’s uncommon, like humans and some other animals and birds do.

Instead, the fish’s life expectancy is heavily influenced by many variables, such as disease, food availability, changing habitat, and general environmental conditions.

In addition, factors, including fluctuations in water quality and temperature and whether the fish falls prey to predators, can play a role in determining an individual fish’s lifespan.

All that being said, some fish species can live for amazing lengths of time before dying, apparently of old age.

For example, some varieties of sturgeon are known to live for up to 100 years, while some deep-ocean fish species, like the Greenland shark, can survive for centuries!

What Are the Signs of Old Age in Pet Fish?

As your fish get older, they generally show several signs of aging, rather like people do.

Decreased Activity Levels

Old fish tend to move around less than their younger tank mates, spending more time resting or hiding rather than swimming, chasing each other, and darting around the tank.

I once owned two large Fancy goldfish that definitely became less active as they aged. Their decreased activity levels became more and more obvious the older the fish became, until at 12 years of age, both my goldies preferred to chill out, hanging motionless in the water or even resting on the bottom of the tank for hours without moving.

Slower Movement

Fish entering the later stages of their lives typically swim with less agility, moving more slowly and with poorer coordination than they had in the past.

Fading Colors

Some fish species are vibrantly colored and incredibly beautiful when they are young, but with age, their colors become to fade and become less bright.

This is often especially noticeable in species that rely on a display of bright colors for territorial displays or spawning, such as betta fish.

Loss of Appetite

Older fish are often less interested in food, and their appetite is reduced, possibly because they are less active, so they don’t require as much energy.

You might also notice that your old fish has become fussier and takes longer to eat his meals.

So, if you have younger, faster fish in the same tank, I advise feeding the oldie in a separate part of the tank, possibly using a feeding ring to ensure everyone gets their fair share.

Buoyancy Issues

Some older fish have problems remaining buoyant and swimming on an even keel, sinking or floating abnormally, possibly because of weakened muscles or age-related swim bladder problems.

Poor Immune Response

Elderly fish often have weaker immune systems than their younger counterparts, making them more vulnerable to diseases, infections, and attacks by parasites.

In addition, old fish typically take longer to recover from diseases.

Physical Abnormalities

Some fish species develop visible signs of physical abnormalities as they age, including growths on the body or a hunched spine.

Reducing Spawning Behavior

Old fish typically show a loss of interest in spawning, and behaviors like courtship displays and territorial aggression might cease altogether.

All these signs vary depending on the species of fish, their individual health, genetic makeup, and overall condition.

However, if you do some research so that you know your fish’s average lifespan, you can be alert to changes in the fish’s behavior, appearance, and appetite that might indicate your pet is approaching the end of his life.

What Do Aquarium Fish Die of?

If you are wondering if aquarium fish die of old age, the answer is no, not usually. So what does cause their death?

Poor Water Quality

Most fish species are highly sensitive to the water parameters in the tank environment in which they’re kept, such as water temperature, pH, ammonia, nitrite, and nitrate levels.

If these parameters are unstable, or if the water quality deteriorates, stress and various health issues will result, ultimately killing the fish.

So, you’ll need to carry out regular water testing to ensure that the parameters in your fish tank are within what’s acceptable for your livestock.

Incorrect Diet

To keep your fish healthy, it’s crucial that you feed them a correct diet in the right amounts.

Generally, fish are carnivores, omnivores, or herbivores, with some species being specialist feeders or preferring a diet that’s rich in meaty protein with a small amount of plant matter.

Again, it’s essential that you do some research to find out what food your fish need to thrive.


Overfeeding is a common cause of death in pet fish. Some species, like goldfish, are extremely greedy and will eat whatever you offer them, which can lead to serious health problems.

Unless you keep a carnivorous species that only require infrequent feeding, I recommend offering your fish two daily feeds of just enough food to last them a couple of minutes.

Insufficient Oxygen

Fish need to breathe dissolved oxygen to survive, and if the oxygen levels in the aquarium are too low, it can cause stress and even suffocation in extreme cases.

Usually, if you have an efficient filter system, the surface agitation it provides will facilitate sufficient gaseous exchange to keep the water well-oxygenated.

I also like to keep plenty of living aquarium plants since they remove carbon dioxide and produce oxygen through photosynthesis.

Incompatible Tank Mates

Some fish species are aggressive or highly territorial, so they don’t do well with others in a community setup.

Belligerent behavior can lead to stress, physical injuries, fights, and even death, so it’s essential that you research and choose fish species that are compatible in terms of size, temperament, diet, and environmental requirements.

Disease and Parasites

Probably the most common cause of death in aquarium fish is diseases caused by bacteria, viruses, fungi, or parasites.

These conditions can weaken the fish’s immune system, often resulting in death if the cause is not promptly diagnosed and treated.

Poor Acclimation

When introducing new fish to an aquarium, it’s crucial to acclimate them to the tank’s water conditions properly.

If you simply throw the fish into the aquarium without acclimating them first, you will stress and shock the fish, making them more vulnerable to disease outbreaks and other health issues.


Stress can be caused by factors such as sudden changes in the fish’s environment, improper handling during transportation or tank maintenance, aggressive tank mates, or inadequate hiding spots.

Prolonged stress weakens the fish’s immune system, making them more susceptible to diseases and generally shortening their lifespan.

How Do I Know My Fish Is Dying?

Do Fish Die of Old Age

Here are some common indicators to look out for that typically indicate your fish is dying or in poor health.

Behavioral Changes

Several behavioral changes are telltale signs that your fish might be on its way out.

If your fish becomes lethargic, loses interest in food, or starts hiding more frequently, it could be a sign that its life is coming to an end.

Abnormal Swimming Patterns

If your fish begins swimming erratically in the fish tank, such as upside down, floating at the surface, or sinking to the bottom, that usually indicates a serious, potentially fatal health issue.

Loss of Appetite

In my experience, when a fish stops eating, that’s a sign that something is seriously wrong and could spell the end for your fishy friend.

That said, keep in mind that some fish species naturally have intermittent feeding patterns, so it might not be curtains for your fish just yet!

Changes In Appearance

Again, many of my fish developed obvious physical changes shortly before they died, including discolored patches, lesions, cloudy or bulging eyes, sores, or signs of fin rot.


If the fish’s gills appear inflamed and its breathing is labored, that can indicate that the fish’s life is ending.

Of course, all those signs could indicate that the fish is suffering from some kind of bacterial infection that could be treated successfully with an over-the-counter medication that you’ll get from your local pet store.

However, if you know that the fish is approaching the end of its natural life expectancy, treatment might not help.


Sometimes, when an elderly fish is sick and has no chance of recovery, the kindest thing to do is euthanize it.

Some years ago, I owned an old goldfish that was showing many of the aforementioned signs of sickness. I tried treating the fish with various medications without success, and in the end, I decided that the best thing for the poor creature was to put it to sleep.

The easiest way to euthanize a fish is to use a sedative, such as TMS, which you can get from your vet, or a natural alternative, like clove oil, which is cheap and readily available from drug stores.

You remove the fish from the main tank and put it into a small container, add your chosen product to the water, follow the dosage instructions on the product packaging, cover the container, and wait. My poor old fish was dead within a matter of 15 minutes with no signs of stress or struggling.

I know that’s a sad ending, but I felt I’d done the right thing by ending the fish’s suffering.

Final Thoughts

I hope you enjoyed this article. If you did, please remember that sharing is caring!

We’ve looked at the question “do fish die of old age” and determined that most do not, especially Aquarium fish. They will most likely die from disease, health condition, or problems caused by poor water quality or stress.

If you keep your fish in a well-maintained environment, feed them a high-quality, correct diet, and keep stress to a minimum, your fishy friends should live full and happy lives. Who knows, they might even exceed their natural life expectancy!

What’s the oldest fish you’ve ever owned? Tell us in the comments box below.

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