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Signs My Oscar Fish Is Dying | Difference Between Healthy And Dying Fish

Signs My Oscar Fish Is Dying | Difference Between Healthy And Dying Fish

Oscars are hardy fish that enjoy long lifespans. When brought up in the right environment, they can easily live past their 20th birthday.

I hate to admit this, but I want to be honest and upfront with you guys. My oscar fish died a couple of days ago. He was just 6 years old. 

And I knew beforehand that his days were numbered. The fish was always diseased. I provided the frail fish the best care I could, but diseases always got better of him. 

My oscar, monikered Jack, breathed its last a few days ago. In the days leading up to doomsday, the fish showed various ominous signs like turning pale and panting.

In this article, I’ll explain in detail what the oscar fish look and behave like before kicking the bucket. 

Keep reading to know! 

Signs My Oscar Fish Is Dying 

The telltale signs that signify the oscar fish is dying are loss of appetite, faded colors, clamped or/and injured fins, weakness, labored breathing, flashing, and erratic swimming/shimmying. 

Remember that not all oscars will display all the signs mentioned above. Also, I don’t claim that the answer above is conclusive by any means. The fish may show various other signs before passing away. 

Having said that, the fish may also show just a couple of signs. For instance, the major red flags when my oscar was sick and on the brink of death were clamping, lack of appetite, and extreme fatigue. The color, too, was noticeably faded. 

Oscar fish are incredibly hardy and can withstand a range of harsh conditions. However, once the disease strikes, lack of treatment can knock down even the toughest oscar fish. 

If you believe your oscar fish is sick, move it to the hospital tank as soon as possible and start the treatment immediately. A stitch in time saves nine. 

Let’s have a look at some of these signs of a dying oscar fish in detail below:

Loss Of Appetite

Oscars have a big appetite. It wouldn’t be wrong to say they are gluttonous fish. They look forward to feeding time and consume food rather greedily. 

However, when death is approaching, the fish often loses its appetite. This is one of the most common signs of impending death. 

My oscar fish’s appetite gradually decreased over a few weeks before it breathed its last. 

Loss Of Color 

Some fish, like discus, turn dark when stressed or sick. In oscar’s case, the opposite happens. The fish turns pale. 

So, if you find the oscar losing its color rapidly, know that something is wrong with the fish. Try to determine its cause as fast as you can and act quickly. 

Clamped Fins 

Clamped fins were one of the first signs of my oscar fish dying. A fish has clamped fins when holding its fins flat against its body. 

Clamped fins are often linked with parasitic infections. It could also mean the fish is profusely stressed. 


Panting or labored breathing is another obvious sign of something wrong with the oscar fish. 

Besides increased respiratory rate, you will find the fish near the water surface gasping for air. 

Abnormal Behavior 

Oscars aren’t exactly social butterflies. But when death is approaching, they will act more reclusive than ever. 

The fish may become irritable and aloof and spend most of the time at the base resting. The fish may also swim erratically. 

Hiding Behavior 

It’s only natural for a fish to hide away when under the weather. Even fish as assertive and aggressive as oscars prefer hiding when they’re not feeling the best. 

If you find your oscar hiding most of the time, you can be certain that something is wrong with the fish. 


Flashing refers to the action when the fish rubs its body against different objects in the tank. It is a very common symptom of different kinds of fish diseases like ich. 

The fish can sustain injuries when flashing, which can lead to grave health conditions in their own right. 

Staying At The Base

Oscars are active swimmers that spend a good chunk of their time cruising through the middle of the water and occasionally foraying to the bottom to find food scraps. 

But with death approaching, the oscar fish often loses any motivation to swim and will spend most of its time resting quietly at the base.

So, we have discussed the signs of a dying oscar fish. But what about a healthy specimen? How can you tell apart a healthy oscar fish from a sick one?

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Signs Of Healthy Oscar Fish 

  • Active and effortless swimming 
  • Good appetite 
  • Rich and clear body coloration 
  • Fins are held erect 
  • Well-proportioned body

Common Oscar Fish Diseases 

Oscars are hardy fish, but they also have their Achilles heel. The five most common oscar fish diseases are hole-in-the-head disease, dropsy, popeye disease, ich, and fin and tail rot. 

Let’s quickly go through them. 

Hole-in-the-Head (HITH) Disease

Hole-in-the-head disease is so common amongst oscars that it is often known as Oscar Disease. Unfortunately, we’re yet to know the exact cause behind this grim ailment. 

However, it is speculated that the possible culprit is a flagellate parasite called Hexamita. This parasite is strongly linked with foul water quality, vitamin and mineral imbalance, overcrowding, and improper nutrition. 

Signs Of HITH Disease In Oscars:

  • Lack of appetite 
  • Large holes and sores 
  • Mucous secretion from the holes
  • White sore on the head and around the eyes
  • Pitting lesions on lateral line and head

HITH Treatment For Oscars:

HITH disease has a high mortality rate. Needless to say, it is fatal if left untreated. According to an Iranian case report, this disease can be treated with metronidazole. 

Also, the condition can be partially or fully reversed by removing all activated carbon. You will have to carry out greater than 90% water change to reduce the effects of activated carbon. 


Ich, also known as white spot disease, is a rampant problem in the hobby. It is caused by a protozoan parasite known as Ichthyophthirius multifiliis.

The parasite responsible for causing ich breeds prolifically and has a complex life cycle, making it tricky to eradicate it completely. 

The parasite thrives the best in warm water and attacks the fish with the weakest immune system. It finds its way into the tank by attaching itself to any new addition like a new fish or plant. 

Signs Of Ich In Oscars:

  • Decreased appetite 
  • Reddened fins 
  • White spots across the body 
  • Listlessness 
  • Flashing 
  • Increased gill movement

Ich Treatment For Oscars:

Depending on how fast you detect and start the treatment, ich can be entirely harmless or downright dangerous. At Urban Fishkeeping, we use the Ich-X solution by Aquarium Solutions to eradicate ich.

Bear in mind that we still don’t have any drug or chemical that can kill ich when it resides in the fish’s skin and gills. All treatments target ich when the parasite is in water. 

All in all, it’s quite tricky to annihilate ich completely. Here’s a link to our detailed guide on treating ich using the Ich-X solution. 

Fin And Tail Rot

Bacterial infection is most commonly the reason behind fin and tail rot. We don’t exactly know what bacteria causes it, but the usual suspects are Aeromonas spp., Cytophaga spp., Flexibacter spp., Flavobacterium columnarae., and Pseudomonas spp.

Just like the hole-in-the-head disease, fin and tail rot happens when the fish is stressed by poor environmental factors like foul water, overcrowding, and low oxygen levels. 

The infection can also occur in tissue damaged by abrasions and wounds. 

Signs Of Fin And Tail Rot In Oscars:

  • Lack of appetite
  • Spending more time on the surface 
  • Bloody, tattered, or blackened fins
  • Lethargy 
  • Slime production

Fin And Tail Rot Treatment For Oscars:

Antibiotics are most commonly used to treat fin and tail rot. If the fish is severely affected, it will have to undergo surgery to remove the infected tissue. 

If it’s a minor case, the tissue will regenerate, and the fins will regrow. It can be treated with over-the-counter medications like oxytetracycline, tetracycline, and chloramphenicol. 

It’s best to consult a vet before starting any treatment. You should also perform a 20-30% water change before the treatment. Adding aquarium salt can also be helpful. 

Popeye Disease 

Popeye, also known as exophthalmia, is characterized by painful bulging of the eyes. The eyes swell and bulge from the socket. 

It is most commonly caused due to poor water parameters and could potentially result in blindness due to loss of an eye. The building is due to fluid buildup in the eye socket. 

The severity of popeye disease can vary quite a bit. In simple cases, the eyes will only experience a moderate amount of swelling. 

In more severe cases, the cornea can be damaged, causing permanent blindness. 

Signs Of Popeye Disease In Oscars:

  • Swollen and bulging eyes 
  • Cloudy eyes 

Popeye Disease Treatment For Oscars 

3 distinct aspects must be addressed when treating popeye disease: corneal damage, fluid buildup behind the eyeball, and secondary bacterial infection. 

Treating popeye can be difficult. Therefore, it’s best to seek professional help as soon as possible. 

You can correct any water quality issue and perform a water change, use antibiotics (recommended by the vet), and add some aquarium salt. 

Even if the treatment successfully saves your oscar, the fish may end up losing the affected eye. While most fish can adapt to being blind in one eye, it will severely deteriorate their quality of life. 

Dropsy Or Bloat

Dropsy or bloat isn’t exactly a disease per se, but it’s a condition triggered by underlying health issues like liver dysfunction, parasites, or infections. 

Dropsy/bloat is characterized by fluid accumulation in the fish’s body, giving it a swollen appearance. 

Often aggravated by environmental triggers, dropsy resolves on its own when the stress is relieved, or the underlying disease is treated. 

Signs Of Dropsy/Bloat In Oscars:

  • Swollen stomach 
  • Protruding eyes 
  • Raised scales 
  • Pale gills 
  • Redness of fins and skin 
  • Swollen anus 
  • Panting
  • Erratic swimming 

Dropsy/Bloat Treatment For Oscars

If bloating is due to constipation, it can be treated by withholding food, performing a big water change, and increasing the water temperature by a couple of degrees.

You can also add aquarium salt, which aids in the osmotic balance of the fish’s body by making the water’s salinity closer to the fish’s blood salinity. Lastly, don’t forget to consult the vet for an antibiotic prescription. 

Frequently Asked Questions 

What Makes Oscar Fish Die?

Disease, coupled with lack of care, causes an oscar fish to die untimely. The most common diseases seen in oscar fish are hole-in-the-head disease, ich, tail and fin rot, dropsy, and popeye disease. 

What Does A Sick Oscar Look Like?

A sick oscar fish will have faded colors and clamped fins. The fish will lose its appetite and prefer hiding. It may also swim erratically and behave skittishly. 

What Is The Life Expectancy Of An Oscar Fish?

The average lifespan of an oscar fish is 15-20 years. However, they often die untimely at a young age owing to their poor upbringing. 

Why Is My Oscar Fish Laying On The Bottom?

The reason behind an oscar fish laying on the bottom could be something as harmless as sleep and overeating to something grim and serious like parasitic and bacterial infections. 

Some other possible reasons include wrong water parameters, swim bladder disease, or just a weird habit. 

Why Is My Oscar Fish Laying On Its Side?

An oscar fish often lays on its side to express stress or submission. However, the fish could also be suffering from swim bladder disease, which compromises its buoyancy. 

Here’s an article that explains 7 unusual reasons why oscar fish lay on its side. Don’t forget to check it out. 

Related: Why Is My Oscar Fish Lying On Its Side? 7 Possible Reasons Why!

Why Does My Oscar Look Pale?

Oscars look pale when they’re sick or stressed. It could also be due to hole-in-the-head disease, which causes white discoloration on the head.

Depending on the condition’s severity, the fish can turn almost white. 

What Does Ick Look Like On An Oscar?

Ich manifests as small white spots dotted across the fish’s body. The parasite penetrates through the skin or gills, burrows under the surface, and eats away the fish’s skin. 

The infected fish will scrape its body against different objects in the environment.

How To Save My Oscar Fish From Dying?

If you think your oscar is dying, the first thing to do is transfer it to the hospital tank so whatever disease it has doesn’t latch on to others. Next, check the water parameters and correct them immediately if anything is off. 

Next, you can add some aquarium salt and raise the temperature slightly. 

What Are Signs Of Stress In Oscar Fish?

The number one sign of stress in oscar fish is erratic swimming behavior. The fish will swim frantically, often crashing at the bottom. Increased hiding behavior, flashing, and fading colors are also linked with stress. 

Final Words: Signs My Oscar Fish Is Dying 

Oscars are hardy fish with a long lifespan. But their lives are often cut short due to illness and stress stemming from a wrong environment and diet. 

When death knocks at an oscar’s door, the fish will lose its motivation to eat or stay active. The fish’s colors will look faded, and breathing will seem labored. Flashing, clamped fins, and shimmying are also signs of disease, indicating death if not treated on time. 

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