What Are Signs of Old Age in Aquarium Fish?

If your fish are getting slower, eating less, looking less healthy than before, or have even come down with strange discoloration problems, chances are that they’re starting to get old.

Not many organisms die because they’re old; they die because the older they are, the more likely they are to be fatally hurt by a disease that would not have been as dangerous in their younger years.

What are the Signs of Old Age in Aquarium Fish?

If you’re looking for more signs that your fish has reached the last parts of its years in your tank, then read on.

They’ve Reached the End of Their Lifespan

One of the most obvious ways you can know whether your fish’s behavior is because of its age is to check its lifespan.

Most fish have a lifespan of around 3-5 years, with the average lifespan of a regular aquarium fish being 7 years, although there are species that even live to 90 years, like the Koi fish.

Goldfish can live up to 15 years, so if you’ve had the same Goldfish since your school days and are now starting your first job, it is possible that your fish is officially old.

In most instances, you can find out more about the particular fish you have by asking the shopkeeper that you purchased the fish from.

They have a better idea and can speak from experience about how long different fish can survive in an aquarium.

Many fish don’t live out their full lives while being in the wild, because predators and the environment can often get in the way.

However, while living in the ideal aquarium conditions, fish are able to live a lot longer than they would otherwise.

This is why your local shopkeeper will have a more precise idea of the lifespan of a fish that you keep in your aquarium.

They Start Losing Weight

Like anyone suffering from old age, many fish will start to lose weight as they get older.

You’ll start to notice that they have a little indent behind their skull, a sign that they’ve started to lose body mass.

You’ll see the indent in the space between their skull and their spine.

You might also notice that their spine has started to lose its natural curvature and leans towards one side—a symptom that they can no longer retain their shape because of weakness.

You might notice that along with losing a lot of weight, your fish might become longer than they were before.

This might be a trick that your eyes are playing on you when your fish starts looking thinner.

Their Eyes Start Bulging

Another element of old age is other organs in the fish’s body going out of proportion.

When a fish starts to lose too much body mass at once, the natural shape and size of the other organs in its body will start looking too large to fit the rest of its body.

Your fish’s eyes might start bulging out of its skull.

They’ll look like their eyes aren’t meant for the size of the body they have, although this is only because the rest of the body is smaller than it should be.

Their Skin Becomes Discolored

Like anyone suffering from old age, a fish will start to undergo discoloration in different parts of its body as the years go by.

You will notice that its natural color will start to fade. It is even possible that the fish’s body starts looking translucent.

This could be for a couple of reasons, like being underweight and old at the same time.

Also read: Can Betta Fish Change Color (or Lose Color)?

They Start Eating Less

Sometimes, when your fish has been stressed out and is aware of their slowly dying state, the anxiety can make them start eating lesser.

If you have noticed that the food you place in the aquarium has been left untouched and your fish is avoiding eating it, your fish could be getting old.

One way to check if your fish is healthy is by encouraging it to eat a pea and checking to see what its poop looks like.

Many fish owners use this tactic to find out whether their fish is suffering from some digestive problems that are stopping it from its usual eating practices.

Appetite is one of the first things you should look out for if you want to spot when a fish is on the verge of death.

This is because eating and reproducing are the main functions of many wild animals and when they stop engaging in these very functions, it is usually not a good sign.

One reason why the loss of appetite becomes a major player in a fish’s death is that if your fish has the potential to heal or recover from an illness, it needs the nutrients that will give it the energy to do so.

When your fish stops eating, it is best to get it checked by a vet as soon as possible, because the more you wait, the more it is likely to succumb to whatever illness it is going through.

They Start Floating on Their Side

The most common way to tell that your fish is getting old is when it starts swimming or floating on its side in the tank.

Many times, a fish that is old becomes too tired to swim and starts floating instead.

They’ll stay in the same place in the tank for hours, and may even sink to the bottom and stay in an isolated corner.

If you’re well equipped with your fish’s regular swimming habits, you will be able to tell if it is behaving differently than it usually does.

The only way to know this is if you are an avid observer of your fish and spend time watching over them in your free time.

If you notice that your fish has either stopped swimming or has undergone a drastic change in the way it used to swim before, then it is possible that it is either sick or has gotten too old to keep swimming the way it used to.

When a fish starts swimming slower and becomes less active, it could be the aftereffects of old age.

They Have Trouble Breathing

When a fish starts experiencing trouble breathing, it is often a telltale sign that it is suffering from something serious.

When you notice that your fish needs to make extra effort to take breaths in, it could be because there is an issue with its gills.

If you want to know whether your fish is having trouble breathing, you can do this by counting the number of times the covers of their gills move up and down.

After figuring out how many times their gills should be moving when they’re healthy, you’ll know if there’s an issue in the way it is breathing right now.

Sometimes, There Are No Signs of Old Age in Fish

Many times, a fish will die without any signs of old age or any illness.

Fish are very sensitive to even the slightest changes in their environment and being old makes it harder for them to get through any major changes.

Sometimes, your fish will appear to be perfectly fine. It will be swimming around and eating properly and then suddenly die the next day.

The reason why fish often do not show any symptoms of old age or suffer from any terminal disease is that they do not express themselves very visibly.

Only someone who has been around fish for many years and is aware of the changes in their moods can tell whether a fish is in distress or behaving differently than usual.

Another reason why fish often do not show any signs of illness is because of evolution. When fish live in the wild, they are often spotted among a school of fish for being weaker than the rest.

They are picked out and eaten for showing any visible signs of illness. This is why your fish has probably adapted a mechanism for appearing well even when it isn’t.

Although this might have worked for them in the wild, it becomes a major cause of their death when they could have been helped by a worrying aquarist.

What Should You Do if You Suspect a Disease?

If you aren’t sure whether your fish is dying of old age or if it has some fatal disease that could be affecting the rest of the fish in the tank, then you should place your fish in a quarantine tank until you have resolved the issue.

A quarantine tank places the fish away from all the other inhabitants of the aquarium, in case there is a disease that it has which could spread to other members of the tank.

Similarly, it also helps you understand whether there was something in your tank that was causing the fish to fall ill.

If your fish’s health improves after being shifted to another tank, it is possible that the water contained a toxin that was affecting your fish’s health.

Many times, the signs of an old fish are intertwined with other diseases, so keeping it in a quarantine tank will help determine if you’re only seeing the symptoms of old age, or if there is a disease that could be hurting your other fish too.

Final Words

In case your fish is actually suffering from old age, keep it in a tank environment that won’t add any stress to it.

Fish are very gentle and can often be difficult to understand.

Once you’re certain that there is no pertinent disease that your fish is suffering from, the most you can do is make sure that it lives its last few days in a comfortable environment.

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