Colorful, active, calm, and low-maintenance, platy fish are a great addition to any freshwater aquarium.
But like any living creature, they can fall prey to sickness and parasites that can negatively impact their health.
In this article, we’ll explore some of the most typical ailments that affect platy fish, including their symptoms, treatments, and ways to avoid them.
Before you can treat them, you need to identify the signs of illness in platies. Then you can figure out the root problem and provide suitable treatment.
List of Diseases Commonly Seen in Platies
1. Shimmies

Shimmies are a common issue among platy fish, characterized by erratic swimming or remaining motionless at the bottom of the aquarium.
This condition can arise due to various factors, including stress, subpar water quality, low water temperature, or insufficient minerals in the tank water.
Symptoms:
- Jerky swimming or staying still
- Clamped fins
- Loss of appetite
- Lethargy
Treatment:
- Improve water quality by performing regular water changes and testing for ammonia, nitrite, nitrate, pH, hardness, and temperature.
- Add aquarium salt at 1 teaspoon per gallon to provide minerals and electrolytes
- Provide hiding places and plants for platy fish to feel secure
- Avoid overcrowding and aggressive tank mates
2. Wasting Disease
Platy fish may contract wasting disease, a bacterial infection that targets their digestive system.
Symptoms of this illness include weight loss, emaciation, a concave stomach, and occasionally the passing of white feces.
Symptoms:
- Weight loss
- Emaciation
- Sunken belly
- White feces
Treatment:
- Isolate infected fish in a quarantine tank
- Feed medicated food with antibiotics such as metronidazole or tetracycline
- Maintain good water quality and hygiene
3. Ich

Ich, also known as white spot disease, is a parasitic infection that affects platy fish, resulting in the development of white spots on their fins and body.
This condition is incredibly contagious and can quickly spread throughout the aquarium if left unchecked.
Symptoms:
- White spots on the body and fins
- Scratching against objects
- Rapid breathing
- Clamped fins
Treatment:
- Increase water temperature to 80°F (27°C) to speed up the life cycle of the parasite.
- Add Seachem Paraguard or aquarium salt at 1 teaspoon per gallon to kill the parasite.
- Treat infected fish in a quarantine tank but apply the treatment at the tank level.
- Keep up the treatment for 4 to 7 days until all spots are gone.
- Gradually lower temperature to normal levels.
- Perform a large water change and clean the substrate thoroughly.
4. Swim Bladder Disease
Swim bladder disease is a prevalent condition that interferes with the buoyancy of platy fish.
Several factors can trigger this disorder, including excessive feeding, constipation, injury, infection, or genetics.
Symptoms:
- Difficulty swimming
- Floating at an angle or upside down
- Balance issues
- Distended belly
Treatment:
- Isolate affected fish in a quarantine tank.
- Fast the fish for 2 to 3 days to relieve constipation.
- Feed the fish with boiled and peeled peas or daphnia to clear their digestive tract.
- Add aquarium salt at 1 teaspoon per gallon to reduce swelling and stress.
- Maintain good water quality and temperature
5. Fin and Tail Rot
Fin and tail rot is a bacterial ailment that can cause the fins and tails of platy fish to appear frayed, ragged, or discolored.
This condition is typically a result of inadequate water quality, stress, injury, or parasitic infections.
Symptoms:
- Frayed, ragged, or discolored fins and tail
- Redness or inflammation at the base of the fins
- White edges on the fins
- Fins falling off in chunks
Treatment:
- Improve water quality by performing regular water changes and testing for ammonia, nitrite, nitrate, pH, hardness, and temperature
- Isolate infected fish in a quarantine tank
- Add Seachem Paraguard or API Fungus Cure at the recommended dose to treat the bacterial infection
- Remove any sharp objects or aggressive tank mates that may injure the fish
6. Velvet
Velvet, also referred to as gold dust disease, is a parasitic infection that affects platy fish, resulting in fine yellowish-green dust on their body and gills.
This condition is highly contagious and can spread rapidly throughout the aquarium if left unaddressed.
Symptoms:
- Fine yellowish-green dust on the body and gills
- Scratching against objects
- Rapid breathing
- Clamped fins
Treatment:
- Increase water temperature to 80°F (27°C) to speed up the life cycle of the parasite
- Dim the lights or cover the tank with a dark cloth to inhibit parasite growth.
- Add Seachem Paraguard or API Super Ick Cure at the recommended dose to kill the parasite
- Treat infected fish in a quarantine tank but apply the treatment at the tank level
- Keep up the treatment for 4 to 7 days until all dust is gone
- Perform a large water change and clean the substrate thoroughly.
7. Fungal Infection
Platy fish can experience fungal infections, which can lead to the development of cotton-like growths on their fins, body, mouth, or gills.
This ailment typically arises from factors such as inadequate water quality, stress, injury, or secondary infections.
Symptoms:
- Cotton-like growths on body, fins, mouth, or gills
- Loss of appetite
- Lethargy
- Redness or inflammation
Treatment:
- Improve water quality by performing regular water changes and testing for ammonia, nitrite, nitrate, pH, hardness, and temperature
- Isolate infected fish in a quarantine tank
- Add Seachem Paraguard or API Fungus Cure at the recommended dose to treat fungal infection
- Remove any dead or decaying matter from the tank
8. Gill Flukes
Gill flukes are parasitic worms that attach themselves to the gills of platy fish and feed on their blood supply.
This infestation can result in respiratory distress, inflammation, and secondary infections.
Symptoms:
- Rapid breathing
- Scratching against objects
- Mucus on gills
- Redness or inflammation of gills
Treatment:
- Isolate infected fish in a quarantine tank
- Add Seachem Paraguard or API General Cure at the recommended dose to treat gill flukes1
- Maintain good water quality and oxygenation
9. Camallanus Internal Worm
The Camallanus internal worm is a type of parasitic worm that can infect the intestines of platy fish, resulting in weight loss.
Symptoms:
- Red, thread-like worms emerging from the anus of the fish
- Abdominal bloating
- Wasting
- Disinterest in food
- Slower growth and reduced breeding
Treatment:
- Administering anthelminthic medication such as Levamisole or Fenbendazole
- Removing any crustaceans that may act as intermediate hosts for the worms
- Performing regular water changes and maintaining good water quality
10. Fungal Infection
Platy fish are susceptible to fungal infections, which can result in the formation of cotton-like growths on their fins, body, mouth, or gills.
This ailment typically arises due to factors such as subpar water quality, stress, injury, or secondary infections.
Symptoms:
- Cotton-like growths on body, fins, mouth, or gills
- Loss of appetite
- Lethargy
- Redness or inflammation
Treatment:
- Improve water quality by performing regular water changes and testing for ammonia, nitrite, nitrate, pH, hardness, and temperature
- Isolate infected fish in a quarantine tank
- Add Seachem Paraguard or API Fungus Cure at the recommended dose to treat fungal infection
- Remove any dead or decaying matter from the tank
11. Viral Hemorrhagic Septicemia
Viral hemorrhagic septicemia is a viral infection that can cause bleeding, organ failure, and eventually death in platy fish.
Unfortunately, there is no cure for this highly contagious illness.
Symptoms:
- Bleeding from eyes, mouth, gills, or skin
- Darkening of body color
- Bulging eyes
- Swollen abdomen
- Erratic swimming
Treatment:
- There is no treatment for viral hemorrhagic septicemia
- Euthanize infected fish humanely to prevent further suffering and transmission
- Disinfect the tank and all equipment with bleach or potassium permanganate
12. Pop-eye
Pop-eye is characterized by the development of bulging eyes that result from fluid accumulation or infection.
The cause of this condition can be attributed to a variety of factors, including poor water quality, injuries, parasites, bacteria, or fungi.
Symptoms:
- Bulging eyes
- Cloudy eyes
- Redness or inflammation around the eyes
Treatment:
- Improve water quality by performing regular water changes and testing for ammonia, nitrite, nitrate, pH, hardness, and temperature.
- Isolate infected fish in a quarantine tank
- Add Seachem Paraguard or API Melafix at the recommended dose to treat the infection
- Treat any underlying conditions that may cause pop-eye, such as parasites, bacteria, or fungus.
Final Thoughts
I hope that this brief overview has provided you with valuable information on diseases that can afflict platy fish, their indications, and remedies.
To keep these fish healthy and content, they require suitable care and attention.
You can ensure the well-being and longevity of your platy fish by following some basic guidelines such as keeping the water quality high, feeding them a balanced diet, avoiding overpopulation and anxiety, quarantining new or sick fish, inspecting your aquarium frequently, and consulting a veterinarian if necessary.
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