Why Do Goldfish Die So Fast? | Aquarium Labs (2023)

Goldfish are normally very long-lived fish. In fact, owning a goldfish is more like entering a long-term relationship. They normally live for several decades when well cared for.

If your goldfish are dying quickly, it is a sign that something is wrong with either their environment or the fish itself. So, why do goldfish die so fast? Let’s talk about several reasons why you might find a dead fish one day.

Table of Contents

  • Poor Water Quality for Aquarium Fish
    • High Levels of Ammonia
  • Adding the Wrong Tank Mates to Your Goldfish Tank
    • Goldfish and Aggressive Tank Mates
    • Good Tank Mates for Goldfish
  • Was Your Goldfish a Carnival or Feeder Fish?
    • Keeping Cheap Feeder Goldfish as Pets
  • Did You Introduce Your Goldfish to the Tank Properly?
    • Temperature and Chemistry Shock
    • Proper Aquarium Setup
  • Death by Goldfish Disease
    • Signs of Sickness and Stress in Goldfish
    • Choosing a Healthy Goldfish
  • Wrapping Things Up
  • References:

Poor Water Quality for Aquarium Fish

Why Do Goldfish Die So Fast? | Aquarium Labs (1)

By far, the common reason why you might wake up one day to find a dead fish is because of problems with poor water quality. Goldfish are very hardy, hardier than most pet store fish, in fact.

They can thrive across a wide range of water temperature and chemistry levels. But if the water parameters stray into toxic regions, then your fish will die very quickly.

High Levels of Ammonia

Why Do Goldfish Die So Fast? | Aquarium Labs (2)

If you have been keeping fish for some time, then you’ve likely come across the term “ammonia” when reading about water quality. Ammonia is the main chemical that fish release as a waste product.

It is produced when fish metabolize protein. In nature, a body of water is usually so massive that fish waste doesn’t create any significant pollution. Ammonia and other fish waste substances are also fertilizers for aquatic plants and algae.

Separated from this web of aquatic life, ammonia can accumulate. If you have too many fish, the problem becomes even worse faster until you have goldfish dying from too much ammonia in the water. Symptoms of high ammonia include black or red patches forming in the skin, lethargy, and inflamed gills.

Excess food is another major reason why tank water becomes polluted. Rather than fish waste, the source is bacteria that start rotting the leftover food, releasing ammonia and lowering the water quality.

Regular water changes and a healthy nitrogen cycle are key to helping a goldfish thrive and live a natural, long life. Goldfish should also be kept in aquariums with filters instead of bowls. Goldfish bowls have no water circulation, change in temperature very quickly, no filtration system, and are far too small for these large, dirty fish. Hopefully, pet stores will one day stop carrying them.

Adding the Wrong Tank Mates to Your Goldfish Tank

Another reason why a goldfish dies is from keeping them in the same tank with aggressive or territorial fish. The nice thing about keeping goldfish is that they are very peaceful, easy-going pets. Even in an overcrowded tank, goldfish don’t pick at rivals, fight, set up territories, or bite. But this is not true of many other fish – in fact, even in a bigger tank, they may decide to make enemies out of your goldfish.

Goldfish and Aggressive Tank Mates

Why Do Goldfish Die So Fast? | Aquarium Labs (3)

Cichlids, large catfish, and certain barbs are just a few of the many aggressive fish out there that may pick on your goldfish. Fancy goldfish are at an even greater disadvantage – their bulbous eyes, slow movements, long fins, fleshy protrusions, and other growths make for obvious targets. And once they have been bitten, these regions can then catch a bacterial infection that may lead to death.

Even normally peaceful fish like plecostomus may decide to take advantage of a slow fancy goldfish. They sometimes attach to their sides, rasping on the nutritious mucus on their skin, which is very stressful to your pets and can cause infections and death.

Good Tank Mates for Goldfish

Tankmates for goldfish need to be considered carefully since they are so peaceful and defenseless. Good tank mates include other large cyprinids like koi, tench, and large vegetarian barbs like Tinfoil Barbs.

Peaceful bottom dwellers like loaches and catfish are also a good match, so they don’t mind cooler water conditions! And, of course, other goldfish are very compatible with one another!

Was Your Goldfish a Carnival or Feeder Fish?

Many aquarists had their first chance to keep a fish as a pet when winning a goldfish as a prize at the carnival! Or you might have decided to give aquarium fishkeeping a try since you had an existing tank, and a feeder fish is an inexpensive entry point.

In both cases, the vast majority of these pets end up dying. Why is that?

It turns out that healthy goldfish need filtration to provide clean water, good quality good, and the same other inputs as any pet. This naturally raises their cost a lot. Pet stores and carnivals both rely on mass-produced cheap feeder fish, which are raised in huge ponds and tanks, overcrowded to the extreme to save money.

When kept in an overcrowded tank, diseases can spread to every fish in the system in a few days. Feeder fish are often covered in ich, mouth rot, body fungus, and parasites.

And even if they don’t have any exterior issues to show their sickness, they are still very fragile from being raised, fighting off both disease and high ammonia levels constantly. Many are weeks or even days away from dying, no matter what you do.

So if you bought a feeder fish and it dies, then it’s more than likely not your fault.

Keeping Cheap Feeder Goldfish as Pets

That said, if your budget can’t be budged or you really want some smaller fish, then feeders can still make good pets. I would strongly recommend quarantining them for a few weeks in a separate tank before adding them to your main aquarium or pond.

This way, you can allow any diseases to manifest to be treated with medication, clean water, and good food.

Feeder goldfish can potentially live as long as any other healthy goldfish. Given how much stress they undergo on a daily basis their entire short lives, it’s unlikely.

But giving these fish a spacious new home with a loving owner instead of a quick death can be a real gift! Feeder goldfish are also good first pets for children who you aren’t sure will remain interested in the tank. This way, you aren’t spending as much as you would on fancy goldfish.

Why Do Goldfish Die So Fast? | Aquarium Labs (4)

Did You Introduce Your Goldfish to the Tank Properly?

If a new fish died within minutes or hours of introducing them to your new tank, then it’s possible that the problem lies with something in the new aquarium’s water.

One reason for sudden death in fish can be due to extremes in temperature. Any time you buy a new fish, you should never simply drop it directly into the aquarium.

Temperature and Chemistry Shock

The shock of hot or cold water can kill even hardy fish like goldfish. Instead, the bag of water and fish you received from the pet store should be floated inside the aquarium for around 15 minutes.

Assuming you came straight home from the pet store, the bag should hold more than enough oxygen. So no need to rush at adding your new fish to the tank!

If I have the time or suspect that the pet stores have water chemistry that is very different from mine, I will take even more time to acclimate my new goldfish.

If the pH is significantly different, say 8.0 vs 7.0 at home, adding a small amount of aquarium water every 15 minutes over the course of an hour will help the fish get used to the difference.

Remember, pH is a logarithmic scale, meaning that a pH of 7.0 to 8.0 represents a tenfold increase in ion concentration, which is a big deal for aquatic animal life!

Why Do Goldfish Die So Fast? | Aquarium Labs (5)

Proper Aquarium Setup

There is more to adding a new goldfish to your tank than just temperature and pH. Any tap water you use to fill the aquarium must be treated with a liquid, fast-acting dechlorinator before adding your pet fish.

Chlorine is added to tap water to kill any leftover bacteria and viruses that the water treatment plants may have missed or are found in old pipes along the way to your faucet.

However, chlorine is also deadly to healthy fish, as well as the beneficial bacteria that live in your filter and substrate. Goldfish die quickly when added to an aquarium filled with untreated tap water.

Death by Goldfish Disease

One of the fastest reasons why goldfish die so fast is because they had a disease that you were not aware of. Many infectious diseases are slow-acting and very obvious.

These include ich, which manifests as a sprinkle of white dots across the skin of the fish. Ich is rarely fatal unless your goldfish is already weakened by something else.

Many diseases are caused by an internal bacterial infection that may not be obvious when looking at the fish. You may see bloating, or the fish may have trouble with its buoyancy, which can be signs of a swim bladder or intestinal illness. Internal parasites are also not at all obvious and can go undetected for the entire life of your pet fish!

Signs of Sickness and Stress in Goldfish

A stressed fish will often act in predictable ways, regardless of the size or species. Clamped fins, lethargy, listlessness, passive floating, and a lack of appetite all signal to you that something is wrong with your fish. The exact cause could be a stressful shift in water temperatures or conditions, parasites, bacteria, or something else.

When you know your fish is stressed, take the time to look for actual injuries as well. Missing scales, small wounds, torn fins…All of these can indicate problems like aggressive tank mates, sharp aquarium decorations, or something else.

Is your goldfish losing weight? Are their colors pale? Are their eyes clear or cloudy? All the fish symptoms listed here can help you diagnose and treat problems before your fish ends up dying.

Choosing a Healthy Goldfish

Why Do Goldfish Die So Fast? | Aquarium Labs (6)

The best way to keep your goldfish from dying quickly is to choose healthy fish from the start! Take the time to study a goldfish you may end up taking home for a few minutes. Are its eyes clear and free of cloudiness or injuries? Is it actively swimming around its environment, with expanded fins and a natural motion?

Sometimes if you ask the pet store, employees will throw in a little food. This way, you can confirm that a potential new pet has a healthy appetite, especially if you are interested in a pricier goldfish.

What if you aren’t 100% convinced of a fish’s health but don’t see any immediate signs of illness? If you can, wait a few days before buying newly imported fish.

Often diseases come up because of the stress involved in shipping fish around the world. They are kept for days in dark, crowded conditions with no food. The fish will often get brief food and rest break at the distributor’s warehouse but eventually ends up being boxed again to be sent to a pet store.

And then, from there, they take one last trip to your home and their new home. All this moving around can be too much stress if they weren’t healthy to begin with.

Wrapping Things Up

Goldfish don’t normally die quickly. They are very hardy, long-lived fish that can live for many decades in the right conditions.

So the most likely answer to a goldfish dying too fast is that either the fish was about to die or there is something about your tank that killed it. Hopefully, the tips in this guide will help you sort out which is which!


Related Goldfish Questions:

  • How Do You Choose Healthy Goldfish?
  • Do Goldfish Even Have Teeth?
  • What Are Good Goldfish Filter Brands?
  • What Are Healthy Food for Goldfish?
  • Can Goldfish Get Seizures?
  • How Long Can Goldfish Survive Without Having Food?
  • Why Is My Goldfish Turning Red?
  • Why Is My Goldfish Turning White?
  • Author
  • Recent Posts

Kelly Stanley

By day, Kelly is a corporate analyst, but by night she's a long-time fishkeeper. She's loved fish for as long as she can remember, and she's always taken on more responsibility for her parents' tanks (both freshwater and saltwater).

At Aquarium Labs, she's dedicated to assisting more people discover pleasure in fishkeeping and teaching them how to develop into expert pet parents.

Latest posts by Kelly Stanley (see all)

  • Do Goldfish Need a Filter?
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  • Why Do Goldfish Chase Each Other?


Why did my goldfish die so quick? ›

Why? The fish can get ammonia poisoning from the still water, their own waste, and the stress of being so active in an undersized tank. The stress and ammonia poisoning will limit their lung capacity and they'll pass away.

Why do my fish keep dying when my water tests are perfect? ›

PH levels must be balanced for fish to thrive. If you notice your fish start to die in large numbers, it could be a sign that your water's pH levels are too high or low. Check with your local pet store which can monitor and regulate your tank's PH levels accordingly.

Why did my fish die immediately? ›

Poor water conditions

Whenever the tank has bad water or water not suitable for the fish's health, it leads to their death. Poor water condition is a big reason why most of the fish die in a fish tank. Therefore, if you are an aquarist, the priority should always be to maintain the water quality.

Why did my goldfish die after a few hours? ›

There are lots of reasons why a goldfish might die. These include: Unsuitable living conditions: For example, keeping your fish in a tank that is too small, or not using a filter. Poor water quality: There are lots of water parameters that you need to balance to keep your goldfish healthy.

Why did my goldfish die in 2 hours? ›

Remember, if your goldfish die quickly after you added them to your tank, it may be because it hadn't finished cycling, you didn't acclimate your fish properly, or they were already in poor health, such as suffering from a bacterial infection or parasite.

Why do my fish keep dying no matter what I do? ›

There are many reasons why fish in your tank keep dying. A few reasons include stress, incorrect tank setup, overfeeding, diseases, and much more. To a beginner, it could look like your fish died for no reason whatsoever.

Should I change the water if a fish dies? ›

A 50–60% water change should be conducted every 5–6 weeks to prevent any type of nitrate accumulations. If a fish dies or there is an outbreak of some disease, go for a 10% water change.

Do dying fish float or sink? ›

Most fish sink to the bottom of their habitats when they die but they become more buoyant as the process of decomposition takes over. Most fish are slightly denser than water, so sink immediately after death.

Why did my fish suddenly die during water change? ›

Because the fish live in the water and the changes happen gradually, they adjust to it. When a sudden, large water change occurs, it causes such a drastic shift in the water parameters that the fish often cannot tolerate it and they die.

Can fish grieve death? ›

In general, grieving is unlikely in fish - unless you have individually bonded fish which might be possible in some species.

Why do all fish die after changing water? ›

If the fish is dying immediately or after a day of water change, the water chemistry and temperature can be blamed. A lot of water parameters alter once you change the water, like water pH, hardness, temperature, micro and macronutrients, etc. An abrupt change may cause the fish to die immediately.

What is the lifespan of a goldfish? ›

Goldfish have a lifespan averaging about 10-15 years, with some varieties living up to 30 years when provided with proper care. Unfortunately, many goldfish do not reach their lifespan potential due to inadequate housing conditions. Housing needs to meet both their behavioural and physiological needs.

Should I bury my dead goldfish? ›

Burial is probably the most popular option for an honorable disposition. Cremation takes quite a bit of work, and throwing the fish into the trash can seems a little heartless, so most fish owners tend to decide on burial.

Why do my fish keep dying in my fish tank? ›

Stress is the number one cause for constantly dying fish, subsequently caused by many reasons related to water quality, unsuitable water parameters, poor aquarium ecosystem, poor fish acclimation, and aggression from other fish, to mention a few.

Why did my fish die in 3 hours? ›

You Didn't De-Chlorinate the Water

Tap water contains small traces of chlorine. This chlorine is safe for human consumption, but is very toxic to fish. If your fish died within a few hours of being placed in the tank, this is the reason.

How do I increase oxygen in my fish tank? ›

Increasing water movement is the quickest way to increase oxygen (O2) levels in a fish tank, as it allows more O2 to dissolve and carbon dioxide (CO2) to be released. This can be easily done using an air pump, performing large water changes, manually stirring the water, or placing a fan near the aquarium.

Do goldfish get lonely if one dies? ›

You might be surprised to learn that, no, they don't. At least, not as far as we know. Based on everything we know about goldfish, it is very unlikely that goldfish feel loneliness. It's normal to wonder whether your goldfish will get lonely if kept in a tank on their own.

Why is my goldfish floating on its back but still alive? ›

Positive buoyancy disorder, where the fish floats at the surface or on its side, is the most commonly presented form of swim bladder disease, especially in goldfish. Most likely, the cause is overinflation of the swim bladder.

How long can a goldfish stay out of water before it dies? ›

Goldfish can actually live for up to an hour out of water. This could be stretched even further is there is at least some water – a small puddle for example. Some goldfish have survived up to three hours on the floor, because some water came with them when they jumped out of the tank.

Why is my goldfish floating but still alive? ›

Many goldfish eat like ravenous Golden Retrievers, sucking in floating food at the surface. In doing so, they inadvertently suck in extra air, resulting in added volume to their swim bladder. Additional air in the swim bladder results in a positively buoyant fish, aka a floaty fish.

What is the best thing to do when your fish dies? ›

Tie it up in a bin bag and place it in the waste. You can bury fish in the garden although make sure you bury it deep enough to stop foxes digging it up, or cats. If your local fish store has asked to see the corpse keep it in the freezer as dead fish rot and smell very quickly.

Should you throw dead fish back in water? ›

Everyone wants the fish they release to survive. Treat those throw-back gently and with respect, and you never know – one of the fish you return to the water today could grow up to be a trophy on the end of you line tomorrow.

How do you keep a dying fish alive? ›

How to Save a Sick Fish
  1. Step 1: Check Your Water Quality. Poor water quality is the #1 cause of illness and disease in fish. ...
  2. Step 2: Fix Your Water Quality. ...
  3. Step 3: Check Your Fishes' Food. ...
  4. Step 4: Call Your Veterinarian About Your Sick Fish.
Feb 25, 2020

How long do you have to clean a fish after it dies? ›

Once fish are dead, it's best to clean them within two hours and eat them within 24 hours. You will need a method of holding your fish until you are ready to clean them. Some anglers use a stringer to keep the fish in the water. Other anglers place fish directly on ice in a cooler.

Can you keep dead fish in water? ›

It is best to weigh fish alive, but keeping dead fish cold and damp will help to prevent water loss if this is not possible. Keeping dead freshwater fish in ice water will result in weight gain if held for an extended period of time.

Can you throw dead fish in water? ›

This decomposition process releases toxic compounds into the water, including ammonia. These toxins can seriously harm other fish that may be in the tank and cause them to fall ill. Not to mention that if a fish died from a contagious illness, that too can spread to your other fish!

What happens if a fish dies but doesn't float? ›

It should also be noted that fish don't necessarily always float when they die. For example, if a fish dies with little to no air in its swim bladder, the act of dying doesn't magically make this bladder expand to increase buoyancy. In these cases, the fish will often sink, at which point decomposition will begin.

How do you calm down a stressed fish? ›

Ways to Reduce Fish Stress
  1. Change water frequently to keep nitrate and ammonia levels low. ...
  2. Check water temperature for consistency regularly to prevent stressful fluctuations.
  3. Provide an optimal filtration system like the Fluval Underwater Filter that captures debris and bacteria while ensuring proper oxygenation.
Mar 2, 2018

Do fish have feelings? ›

Nerves, brain structure, brain chemistry and behaviour – all evidence indicates that, to varying degrees, fish can feel pain, fear and psychological stress.

How do you tell if a fish is in shock or dead? ›

Check the fish's eyes.

Look at the eye as a whole. If they're sunken, your fish is dead or near death. Look for cloudy pupils, which is also a sign of death in most aquarium fish. If your fish is a pufferfish, walleye, rabbit fish, or scorpionfish, occasional eye cloudiness might actually be normal.

How do you know if your fish is sad? ›

Strange Swimming: When fish are stressed, they often develop odd swimming patterns. If your fish is swimming frantically without going anywhere, crashing at the bottom of his tank, rubbing himself on gravel or rocks, or locking his fins at his side, he may be experiencing significant stress.

Why did my goldfish die suddenly after water change? ›

Because the fish live in the water and the changes happen gradually, they adjust to it. When a sudden, large water change occurs, it causes such a drastic shift in the water parameters that the fish often cannot tolerate it and they die.

Why are goldfish so hard to keep alive? ›

Most goldfish aren't hardy and tough enough to stand little oxygen and lots of toxins in the water (especially the fancy varieties). So it's only a matter of time before they die.

Do goldfish float when they die? ›

Most fish are slightly denser than water, so sink immediately after death. However, like a drowned human, they become more buoyant over time as bacterial decomposition produces gases inside the body. Usually, enough gas builds up in body cavities to make the corpse float, like an inflated balloon.

What do goldfish look like before they die? ›

See if you notice any small, white or black spots on your fish. White spots may indicate that your fish has ich, which is a common parasite found in goldfish. Check for bloated or raised scales. If you see any bloating or protuberance where you've not seen one before, it could mean that your goldfish is ill.

Why do my goldfish keep dying in tank? ›

Stress is the number one cause for constantly dying fish, subsequently caused by many reasons related to water quality, unsuitable water parameters, poor aquarium ecosystem, poor fish acclimation, and aggression from other fish, to mention a few.

How long can a dead fish stay in tank? ›

It depends on what the cause of death was. If the water quality was perfect and all other fish, including members of its own species, appear OK and look free of disease you could restock within a week. Leaving it for a full seven days is best, as if others die within that time you'll know there's an underlying problem.

What is new tank syndrome in goldfish? ›

New tank syndrome leads to ammonia toxicity in the fish, which can quickly become fatal. Fish will often die suddenly, without warning. The aquarium water is frequently cloudy and smelly due to the excessive ammonia and nitrite levels.

What is the easiest goldfish to keep alive? ›

There are many varieties of goldfish, but beginners should start with long-body goldfish, including the comet, sarasa, and shubunkin varieties. Fancy goldfish with unusual body shapes are better for more intermediate fish-keepers.

How long are goldfish supposed to live? ›

Goldfish have a lifespan averaging about 10-15 years, with some varieties living up to 30 years when provided with proper care. Unfortunately, many goldfish do not reach their lifespan potential due to inadequate housing conditions. Housing needs to meet both their behavioural and physiological needs.

Can a goldfish live in tap water? ›

Goldfish cannot live in untreated tap water

Goldfish can only live in tap water when it has been properly treated to remove harmful chemicals. Tap water contains chemicals that will kill all of the 'good bacteria' in your tank.

Why is my fish pretending to be dead? ›

Some species play dead to fool other fish, often targeting scavengers as a food source. The Central American cichlid is a perfect example. In other species, though, this behavior might hint at a health issue.

What to do with a dead goldfish? ›

Tie it up in a bin bag and place it in the waste. You can bury fish in the garden although make sure you bury it deep enough to stop foxes digging it up, or cats. If your local fish store has asked to see the corpse keep it in the freezer as dead fish rot and smell very quickly.

Should you flush a dead goldfish down? ›

You're not supposed to flush the fish down the toilet, so how can you properly dispose of it? If unsure what to do with a dead fish, one option is to put it in a plastic bag and bury it in your backyard. You can also throw it into the garbage or even consider cremating your fish as well.

Do goldfish feel pain? ›

Fish do feel pain. It's likely different from what humans feel, but it is still a kind of pain.” At the anatomical level, fish have neurons known as nociceptors, which detect potential harm, such as high temperatures, intense pressure, and caustic chemicals.


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