What Are The Signs of A Sick Oscar Fish

Oscar fish is one of the beautiful colored fish that is usually part of aquariums. Sometimes, they are on the receiving end of the diseases and lose their beauty. In swear cases, mortality happens. It is better to understand Oscar fish diseases and the factors behind these diseases. Moreover, how to treat sick Oscar fish, is another important aspect to see their beauty in the tank. You will find all of these things in the following.

Do Oscar Fish Get Disease

Yes, Oscar fish get disease. There are several diseases that Oscar fish can receive. Some of the most common diseases are listed in the following.

Hole in the Head (HITH) Ich Fin and Tail Rot
Columnaris Dropsy Neon Tetra Disease
Popeye Disease Scoliosis Gill Flukes

What Causes Oscar Fish Diseases

Hole in the Head (HITH)

A hole in the head is a common disease among cichlids and Oscars. It is also known as Freshwater Head and Lateral Line Erosion (FHLLE). It is mostly associated with the old fish, due to a decrease in the immune system.

Many reasons behind this HITH disease:

  • Hexamita parasites infect the intestinal tract, which leads to the said disease
  • Imbalanced nutrition
  • Use of activated carbon and other chemical filter media.
  • Overcrowding.

More info about why fish have a hole in the head


Ich is also known as white spot disease or Ick. Ichthyopthirius multifiliis parasite is responsible for this. It can be transmitted to aquariums through equipment, plants, or new fish.

oscar fish diseases

Fin and Tail Rot

Fin and Tail Rot is another common preventable bacterial disease among Oscar fish aquariums. Aeromonas or Pseudomonas bacteria is the main root of this disease.

Several reasons cause it:

  • Poor water conditions
  • Overcrowding
  • Company of aggressive fish.


Columnaris is another bacterial disease among Oscar fish. It is also known as cottonmouth disease. Flavobacterium columnaris cause of this ailment.


Dropsy is another Oscar fish disease. It happens due to gram-negative bacteria. This bacterial infection can prove lethal and even a reason for fish death. It causes fluid accumulation in the gills or body cavity.

Popeye Disease

It is another Oscar fish disease. It is caused when a fish becomes super excited, runs toward some decoration or object, and hits the eye with that. Popeye’s disease in betta fish is also a very common fish disease.


Scoliosis is also known as bent spine or broken back disease. The back of the Oscar fish becomes a C shape.

It is usually caused by the following reasons:

  • Deficiency of vitamin C.
  • Injury
  • Genetic disorder
  • Certain infections

Gill Flukes

Flukes are a parasite born from Oscar fish disease. Here are some reasons for gill flukes.

  • Poor water quality
  • Overcrowding
  • Malnutrition
  • The company of some aggressive fish.

how to treat sick oscar fish

The Signs of Sick Oscar Fish

How to treat sick Oscar fish can be well answered, once you understand better the signs of a different Oscar fish disease. Loss of appetite, weight, discoloration around the affected area, and lethargy are common signs that indicate a sick Oscar fish. The rest of the signs are discussed in the following.

Hole in the Head
  • Excessive small holes around the eyes, on the head, and along the lateral line pattern.
  • Mucus (a white slimy fluid) coming out from the holes.
  • The wound or lesions usually appear white, red, or grayish.
  • The most prominent sign is the appearance of numerous white spots on fish skin.
  • Fish often rub against aquarium walls, decorations, and rocks.
  • Increase in gill moment.
  • Instead of spreading its fin, fish close its fin to the body.
Fin and Tail Rot
  • Ragged appearance of fin or tail.
  • Fish try to bring the fins close to the body in case of pain.
  • Deteriorating edges of fins and tails.
  • Pale grayish patches appear all around the fish.
  • Rapid gill moment.
  • Pale grey or yellow slimy substance around the fins.
  • Swimming pattern changes.
  • Try to rub itself along the surface of different objects.
  • Fish hang on the surface.
  • The body size increases, due to the fluid build-up in body organs.
  • Difficulty in swimming.
  • Increase gill moment and cause difficulty in breathing.
Popeye Disease
  • One or both eyes became bigger and bludging out.
  • Redness is there.
  • Clear curvy spine.
  • Lose swimming style and show unwanted spiral moments.
  • Rest in some altered posture.
Gill Flukes
  • Rapid gill moment.
  • Redness around the gills.
  • Fish rub themselves against the objects or aquarium wall.
  • Excessive mucus on the gills.

How to Treat Sick Oscar Fish

Treatment is an important aspect after proper diagnosis. Some general precautions are required for every disease. Along with these general treatment methods, you also need to know about specific methods about how to treat sick Oscar fish.

General Treatment for the Disease

Here are some general treatments to adopt as you find some sickness signs in your Oscar fish.

  • Check the Water parameters

Check the water parameters with test strips whether they are normal or if some fluctuation is there. If there is some variation, then bring them back to a normal level. Here are some general parameters to check, i.e., pH, hardness, ammonia, nitrate, and nitrite levels. Don’t forget to check the water filtration condition.

  • Quarantine

Quarantine the sick Oscar fish to avoid the spread of disease in the rest of the tank.

  • Balance nutrition

Provide a balanced nutritional diet to sick fish.

  • Calm the environment

Make the aquarium environment more peaceful by following these instructions.
Set the lighting time, according to the fish, plants, and tank’s capacity.
Introduce the compatible fish and plants in it.
Replace the sharp edge objects with round face objects to avoid any injury.

  • Consult with a vet

Consult with a veterinarian in case of any abnormal sign or moment in your Oscar fish. It will help to prevent your fish from falling into serious sickness in time.

sick oscar fish

Hole in the Head (HITH)

  • Use the antibiotic specifically designed for the hole in the head. Generally, vets recommend metronidazole or nitrofurazone.
  • Provide supplementary vitamins C and E to boost the immune system.
  • Reduce the noise-creating component from your fish tank.


  • Raise the water temperature by 2 degrees centigrade.
  • Remove the carbon filter.
  • Give them an aquarium salt bath.
  • Malachite green and formalin help to cure the disease.

More treatment about treat Ick fish disease.

Fin and Tail Rot

  • Give them a dose of antibiotics. Erythromycin and tetracycline are found useful.
  • A salt bath is also fruitful.


  • Using antibiotics, i.e., sulfonamides or furan helps to treat Columnaris-affected Oscar.
  • Gradually decrease the water temperature.
  • Remove the carbon filter or any other chemical filter media.


  • Epsom salt baths help to reduce the swelling.
  • Use antibiotics, i.e., SeaChem’s KanaPlex or Mardel Maracyn II.

Guide to treating dropsy or bloating in fish.


  • Use antibiotics, i.e., kanamycin or erythromycin to treat Popeye.
  • Anti-fungal medicine is also suggested in case of any fungal attack on the affected area.
  • An aquarium salt bath is also a better option.


  • Increase vitamin C dose in affected fish diet to improve the skeleton.

Gill Flukes

  • Praziquantel and formalin are specifically formulated for the gill fluke parasite.
  • A salt bath is another useful option to heal from gill flukes.
  • Increase oxygenation of the tank with an aeration strip kit.

Blue oscar fish

In Closing

These are some of the most common Oscar fish diseases. It is better to understand it at a very early stage to avoid any unwanted results. Moreover, following how to treat sick Oscar fish section to treat them in time, or consult the Vet for a proper deeper treatment.

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