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What To Do When Your Fish Is Dying? Try These 5 Things!

What To Do When Your Fish Is Dying? Try These 5 Things!

Credits: Matt Elsberry (Creative Commons license)

A pet fish dying is a very bitter experience. Although we don’t share an explicit bond with fish as we do with furry pets, they really grow on us in unexpected ways. Don’t they? That’s why today we will discuss what to do when your fish is dying. 

Let’s begin!

What To Do When Your Fish Is Dying?

If you think your fish is dying, there are certain things you can do to help it recover from the illness or make the death experience as comfortable as possible. For that, make sure the correct water parameters are met and quarantine the fish for treatment if necessary. If the symptoms persist, you should consult a vet immediately. 

Check The Water Parameters 

The one-size-fits-all attitude is the number one reason behind untimely death in fish. The fish may prefer hard or soft water, cold or hot water, and freshwater or saltwater depending on where it comes from and its genetic coding. 

So, the number one thing to do is check the water quality in the tank. 

For that, we recommend using liquid-based kits like this one from API Freshwater Master Kit. Don’t waste your money on those silly strips that are accurate and expensive on top of that! 

Here’s a quick glance at water parameters:

Freshwater Parameters 

ParameterFreshwaterAfrican CichlidBrackish
Temperature72 – 82°F72 – 82°F72 – 82°F
pH6.5 – 7.57.8 – 8.57.5 – 8.4
Nitrate< 50 ppm< 50 ppm< 50 ppm
Carbonate Hardness4 – 8 KH10 – 18 KH10 – 18 KH
General Hardness4 – 12 GH12 – 20 GH12 – 20 GH

Marine Parameters

ParameterSuggested Level:
Reef Aquarium
Suggested Level:
FOWLR Aquarium
Average Level:
Coral Reefs
Specific Gravity1.023-1.0251.020-1.0251.025
Alkalinity8-12 dKH8-12 dKH6-8 dKH
Ammonia (NH3)Nil Nil Near Zero
Nitrite (NO2) Nil Nil Near Zero
Nitrate – Nitrogen (NO3)< 1.0 ppm< 30 ppm0.25 ppm
Phosphate (PO4)< 0.2 ppm< 1.0 ppm0.13 ppm
Calcium350 – 450 ppm350 – 450 ppm380 – 420 ppm
Magnesium1250 – 1350 ppm1150 – 1350 ppm1300 ppm
Iodine0.06 – 0.10 ppm0.04 – 0.10 ppm0.06 ppm
Strontium8-14 ppm4-10 ppm8-10 ppm

As specific as I’d love to be, the above charts display general parameters. It’s wise to google the exact parameters for your fish species and try to achieve that. 

Fix The Water Parameters 

Fish are susceptible to foul water. And 9 out of 10 times, it is a polluted tank that’s causing the illness. To lower the nitrate and ammonia concentration in the tank, you can perform partial water changes, add live plants, cut back on feeding, and upgrade to a bigger tank or more powerful filtration mechanism. 

You can also use this aquarium water clarifier by Algone that effectively removes both nitrate and ammonia, as well as the cloudy appearance of the tank. 

Also, keep an eye on the pH and temperature. 

However, you mustn’t make fast corrections. Fish don’t adapt well to sudden environmental changes. This will severely stress out the fish and backfire in the worst ways possible. 

All the changes should be made gradually over a couple of hours or days. For instance, don’t use ice cubes or ice packs if you need to lower the water’s temperature. Instead, rely on a fan or the air conditioner. 

Quarantine The Fish 

Quarantine the sick fish as soon as you identify it. For this, fill the hospital tank with as much mature water as you can spare from the main aquarium. 

Feed and perform water change as usual. 

Treat The Fish With Salt Bath 

A salt bath can often be the best medicine for a sick fish. It can impart numerous health benefits. But note that if your fish is already on medications, you can only give it a salt bath before you give it any other medications. 

You can use sea salt, aquarium salt, kosher salat, or pure Morton’s rock salt. If possible, we recommend using natural sea salt that doesn’t have any additives. They’re high in minerals. 

Use a medium-sized clean container. Add tank water to it or use freshly dechlorinated water if the tank water isn’t safe for use. 

Next, add one teaspoon of salt for each gallon of water and stir it till it dilutes. Then, transfer the fish to the container and keep it there for 3-4 minutes. 

If the fish shows any signs of discomfort or stress, move it to the main tank immediately. 

Feed Sparingly 

In the wild, fish eat small, frequent meals. So, make sure that you follow a similar pattern in the tank. Overfeeding or starving your fish will both have negative repercussions. 

Small feedings are also easier on your aquarium’s filtration system. 

You can give blanched veggies and live food as occasional treats and zero in on commercial fish food from a reputed brand for a staple diet. 

Most commercially manufactured fish foods are specifically formulated to fulfill all the nutritional requirements. 

And remember, once you open any type of fish food container, you can only feed from it for around 6 months. After that, you’ll need to toss it in the dustbin. 

Consult A Vet

I admit, calling a veterinarian can burn a big hole in one’s pocket. On top of that, it’s hard to find a vet that specializes in treating fish. But sometimes, calling the vet and seeking professional help is the best thing you can do. 

The vet will ask for a record of complete history like what species are kept together, what fish are affected (size, age, species), water parameters, and any new addition to the tank. So, make sure you go equipped with all the knowledge you need. 

You will also need to bring a sufficient amount of the original tank water provided that it’s safe. 

Recommended Readings!

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Do Fish Feel Pain? 

Yes, of course. Fish can very much feel pain. Growing scientific evidence has dispelled the myth that fish are nothing more than a bunch of protein swimming mindlessly in water bodies. 

Fish have highly developed nervous systems and pain receptors that make them capable of experiencing a broad spectrum of pain, like being suffocated and pierced by a hook. 

How To Tell If Your Fish Is Sick? 

The following are the signs of a sick fish 

  • Loss of appetite 
  • Lethargy and weakness 
  • Lack of socialization 
  • Clamped fins 
  • Flashing 
  • Shimmies 
  • Loss of buoyancy 
  • Gasping for air/panting 
  • Erratic swimming patterns 

I’ll explain some of the main signs in brief below.

Clamped Fins 

Fish have clamped fins if they tightly hold their fins closer to their body. And fish aren’t supposed to clamp their fins – they’re supposed to open the fins. 

If you find your fish clamping its fins often, the chances are that the fins are also frayed (damaged or torn). 

Clamped fins are a common sign of many diseases in fish. Therefore, it’s essential to deduce the right reason by gauging some other signs as well. 


Flashing is a behavior depicted by fish to get rid of the itchy sensation in their bodies. This symptom is most commonly associated with parasitic infestations. 

Since fish don’t have limbs, they rely on their surroundings to scratch themselves. Therefore, rare occurrences of flashing are not a cause of worry. However, if your fish flashes often and you fail to take the right intervention, the fish may die from flashing too severely. 


Shimmies refer to a behavior where the fish rocks and shakes its body from side to side in an almost snake-like slithering motion. It’s especially common in livebearers like mollies, guppies, and swordtails. 

The number one cause behind shimmies is cold water. The fish then try to warm their body by ‘shivering.’ If the right water conditions (especially temperature) are met, this symptom will often disappear on its own. 

Lack Of Socialization/Change In Schooling Behavior 

Most aquarium fish we raise in our homes are ‘schooling’ fish – meaning they prefer to swim in a group of their own species. So if there’s plenty of space in your tank, you will easily and often observe schooling. 

However, a sick fish will refrain from swimming in a school or engaging in any social activity. Instead, it will appear aloof and retire to one corner of the tank. If you find a fish displaying such behavior, make sure to observe it if anything’s wrong with it. 

Loss Of Buoyancy 

Loss of buoyancy is often caused by bloating or the malfunctioning of the swim bladder. If it’s due to bloating, you need to fast your fish for a couple of days (3 days approx.) and feed peas (cooked and skinned) on the 4th day. 

If it’s due to the malfunctioning of the swim bladder, which in turn is due to an abnormality or an injury, you need to seek professional help for your fish. 

Erratic Swimming Pattern 

Fish usually have a set preference of where they swim, depending on the species. For instance, bettas and danios are known to be surface-dwellers. On the other hand, angelfish will swim throughout the tank.

So, if the fish changes its swimming pattern or swimming region, this should be a matter of concern. 

As stated in the list above, lack of appetite, labored breathing, and lethargy are equally concerning. 

Now, let’s look at a few signs of a healthy fish. 

Signs Of A Healthy Fish 

  • Rich coloration of the body and the gills 
  • Good appetite 
  • Erected fins 
  • Swims actively and effortlessly 
  • Alert and social
  • Well-proportioned body 

Why Do Fish Die?

As much as we don’t like to admit it, we don’t understand fish anatomy or bodily functions as much as we should or would like to. So, we’re often taken by surprise when we find a fish lying motionless at the bottom with frayed fins and bulging eyes, don’t we? But, don’t worry – we’ve all been there. 

Here are a few common reasons fish die in an aquarium:

  • High levels of ammonia, nitrite, and other harmful compounds
  • Low levels of oxygen in the tank result in suffocation 
  • Big and sudden water changes 
  • Sudden change in temperature 
  • Exposure to cleaning detergents, perfumes, and soaps 
  • Overfeeding or underfeeding 
  • Lowered immunity due to stress 

When To Euthanize A Fish?

  • When an untreatable disease occurs
  • When breeding for specific features 
  • When there’s an ecological threat 
  • When the fish is too old

When An Untreatable Disease Occurs 

If your fish has a highly contagious or untreatable disease, the best thing you can do for the ailing fish and the rest of the tankmates is to euthanize it. 

Some common conditions that demand euthanasia are when the fist displays severe dropsy, doesn’t respond to medications, is repeatedly prone to diseases or is the host for infectious pathogens in the tank. 

When Breeding For Specific Features 

When breeding fish for selective characteristics, we often have to euthanize (cull) the fry that don’t appear to be good candidates.

Culling may seem inhumane at first glance, but leaving the fry in the wild to fend for themselves is far more dangerous to the environment. The fry can very much grow to become an invasive species and threaten the very existence of native species.

When There’s An Ecological Threat 

Continuing from the pointer above, a fish is a good candidate for euthanasia if it can possibly contaminate the area’s natural environment and outcompete the local species. 

When The Fish Is Too Old

This is very subjective. If your fish is old but living its best life, there’s absolutely no need to euthanize it. On the other hand, if your fish is constantly sick and is a potential breeding zone for deadly pathogens, maybe it’s time to put it out of its misery. 

Can You Flush A Dead Fish? 

No, you should not flush a dead fish. This isn’t just disrespectful to your beloved pet but also can potentially cause ecological disruptions. 

First thing – our septic systems, as robust as they look, aren’t designed to handle anything other than feces and toilet paper. 

Next, if the fish wasn’t actually dead by any chance, it may make its way into the local waterways, where it can disrupt the existing ecological system and threaten the very existence of the native species. 

The second pointer may seem far-fetched, but you’d be surprised to know the number of times this has happened and wreaked havoc! 

Also, don’t throw the fish outside or feed it to other animals. 

What you can do is bury the fish in a safe place or cremate it. 

Frequently Asked Questions 

Credits: The Reptilarium (Creative Commons license)

How To Save A Dying Cichlid? 

To save a dying cichlid, first, make sure the water parameters in the tank are correct. If they aren’t, gradually bring them to the right levels. You can also transfer the fish to the hospital tank, quarantine it and use necessary medications like a salt bath depending on the diagnosis. 

If the symptoms don’t subside in a few days, you might want to seek professional help. 

What To Do When Your Betta Fish Is Dying?

If your betta fish is dying, first, get to the root of the problem and identify the source of the disease. Then, if necessary, transfer the fish to the hospital tank and use appropriate treatment.

Final Words: What To Do When Your Fish Is Dying?

A fish’s untimely death is a tragic event. However, if you are able to dissect what’s causing the problem at the right time, you might just be able to save it. 

Look for any symptoms of illness or stress as mentioned above. Also, check if the water parameters are suitable or not. Once you are able to diagnose the problem, apply necessary treatments. And if the disease is contagious, don’t forget to immediately transfer it to the hospital tank. 

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