Common Goldfish Diseases

Listed below are the most common diseases goldfish contract.

Once you have looked through the common goldfish diseases and identified the ailment your goldfish may be suffering from, click on the link to take you to treatment options.

Many treatment options are similar if you are unsure exactly what is troubling your Goldfish.  The most important thing to establish is whether the disease is fungal, bacterial or caused by parasites. 

Swim bladder disorder is one of the most common Goldfish diseases in fancy Goldfish varieties.

Swim Bladder Disorder

Symptoms: Fish is unable to swim normally because of buoyancy or balance problems.

Swim bladder disorders cause fish to float to the surface or sink to the bottom.  The most common cause is indigestion/constipation brought on by poor quality food.

Goldfish attacked by fungus.

Fungus (Saprolegnia ferox)

Symptoms: Patches of white cotton wool on the fins or body.

Adult fish louse.

Fish Louse (Argulus trilineatus)

Symptoms: Goldfish rubbing themselves vigorously on the sides, bottom and objects within the aquarium or pond.

The lice are fairly translucent, about an eighth of an inch in diameter, and lay flat against the body of the fish.

Anchor Worm (Lernaea cyprinacea)

Symptoms: Initially it looks like a bony splinter protruding at an angle from the fish’s body.  Over time the irritation causes a bloody red patch that has a small thread protruding from the center.

Black moor displaying Ich infestation.

Ich (Ichthyophthirius multifiliis)

Symptoms: Pinhead size white spots covering the body and fins.

Tail Rot Or Fin Rot

Symptoms: Tips and leading edges of fins become ragged, gradually moving inwards towards the base of the fin.  Mainly affects the caudal fin.

Congested Fin Veins

Symptoms: Blood vessels in fins become swollen and red.  Fins will start to split if left untreated.  The parasite Cyclochaeta is often associated with this condition but it may be an opportunistic infestation.

Goldfish displaying pine cone or dropsy disease symptoms.


Symptoms: The scales of the fish extend giving the fish the appearance of a pine cone.  The scales start to extend from behind the head moving along the fish’s body. The fish’s body will appear bloated.

Pond Pest Or Red Pest (Bacterium cyprinicida)

Symptoms: Blood red patches appear on the fish’s body.  This is hard to detect on red fish.  Clamped fins and loss of appetite will indicate something is wrong.

Water Bubble Eye with a small ulcer above the pectoral fin.


Symptoms: Ulcers appear as a red, pink/red or white open sore on the body.  They are caused by bacteria attacking the skin and surrounding tissue.  The cause of the bacterial attack can be poor water conditions, injury or parasites.

Ulceration (Achlya)

Symptoms: Filminess of the eyes and swollen gills.  It must be treated swiftly.

Flukes (Gill Dactylogyrus, Skin Gyrodactylus)

Symptoms: Twitching of fins and sudden movements of the fish as if startled.  It attempts to rub off the flukes by scraping itself against the gravel or objects in the pond or aquarium.  Both flukes are barely visible to the naked eye.  If one fish has them, it can be assumed the whole aquarium population has them.

Skin flukes are most easily seen on Black Moors as tiny white worms about 1mm long.

Costia disease is a small protozoan parasite that attacks Goldfish.

Costia (Ichthyobodo necatrix)

Symptoms: Similar to flukes with twitching of fins and flashing.  Red or white patches common on the body and fins.  Labored breathing is an indication the parasite has infested the gills.  Fins will often split and fray in advanced cases.

Velvet (Oodinium sp.)

Symptoms:  Almost invisible on gold goldfish, but is quite evident on dark colored fish as a powdery light tan covering.  Heavily infested fish have a hazy appearance and swim in a listless manner near the surface.


Symptoms: Fish swims in a listless or unbalanced manner.

Excreta will hang from the anal pore for a length of time and may be light colored or have gas bubbles interspersed in it.

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