Guppy Diseases, Parasites, and Treatment

By Nadine Oraby | 2020 Update

Just like any creature on the face of the earth, there is no such thing as a truly independent organism. Tons of parasites and microorganisms exist that can cause diseases and harm.

What are some guppy fish diseases? A few common guppy fish diseases include ich, hole in the head disease, and gill flukes. Most guppy fish diseases are easier to prevent than curing or giving treatments to sick fish.

Common Guppy Diseases & Treatment Methods (Video)

This article is not too scientific, but it can hopefully be helpful in keeping your guppy fish healthy and safe in its lifetime.

General Overview

Since guppies can fall sick for so many reasons, the simplest things one can do is to keep the water parameters stable. Make sure that the tank cleanliness is maintained and feed them suitable and healthy foods.

Responsible fish keepers make it a habit to inspect their fish daily for signs of illness and put the sick ones in quarantine. In case a fish dies in the community tank, experienced fish keepers remove it immediately from the water as the dead fish might contaminate it.

Like most creatures, too much stress can weaken a guppy fish’s immune system. This makes them much more susceptible to infections and parasitic infestation caused by contaminants in their environment.

Guppies have a calm behavior, so you should choose other fish that are equally sociable if raised together to at least alleviate a stressful, tension-filled habitat for both kinds.

Trivia: Types of Parasites

There are two main categories of parasites, namely:

  • Microparasites: microscopic organisms such as parasitic viruses, bacteria, fungi and protists that typically multiply directly inside a host.
  • Macroparasites: larger organisms such as worms, insects, ticks, vertebrates and plants that usually leave their produced offspring on a host to substantiate further infections or disease.

Parasites show adaptations for locating their preferred host species and for establishing themselves on or in them. Included among these adaptations are methods for feeding from host tissues and for maintaining transmission from host to host.

In a typical multi-host life cycle, a parasite infects different hosts at different stages of its development, making specific adaptations as it passes from one host to another.

Parasites of the Guppy fish

Parasites that attack aquatic creatures are contagious. If this happens, it is advisable to immediately remove the infected fish from the tank and continuously monitor it through a portable container.

This will help you avoid contaminating or spreading the parasites to other fish in the tank.


There are two types of flukes that affect guppies

  • Skin flukes
  • Gill flukes

A skin fluke binds or attaches to the fish skin and causes severe swelling, while the gill flukes attack its gills, turning them pink. This makes the fish breathe heavily or harder. Often, such fish are found near the water surface where breathing is easier.


Also known as ich/ick or white spots, this is the most common type of freshwater fish parasite.

The signs that your guppy fish is infected by white spots may include the white spots themselves along with rapid loss of appetite, rubbing against objects, flashy movements, and hiding unusually.

This ich is contagious, so the immediate solution to avoid its spread to the other tank inhabitants is to put the infected fish into quarantine.


A kind of parasitic diplomonads related to giardia, which are mostly present in animal intestines.

It is also known as the cause of “hole in the head” disease in fish. This is an internal parasite that strikes the fish when its immune system is weakened through age, stress or poor water conditions.


Also termed as velvet (oodinium), it is a microscopic parasite causing the fish scale to have golden patterns appearing (named the “gold lust” disease).

It almost has the same symptoms as the ich; the only difference is the golden color of the spots.


All these creatures know is to feed on blood. They suck all the blood their body can contain, and leave as soon as they’re full.

Blood loss could be fatal to a small fish such as a guppy, so leeches should immediately be removed from the guppy’s body very carefully.

Pulling it off suddenly can cause infection if it leaves the leech’s suckers in the guppy’s body. So, as a remedy, scrape off the hooked sealant of the suckers from the small end to the larger in order to totally remove its attachment.

Anchor Worms

These parasites occupy the guppy’s body by piercing its flesh and burying itself inside the fish. Its head is anchor-shaped and protrudes a small worm-like or white tentacle extending outside the guppy’s body. So, it cannot easily be pulled off as it may slice the body of the fish or it may cause a profusely bleeding wound.

Fish Lice

Same as the anchor worms, this is a member of the copepod family/ crustaceans.

This parasite is hard to diagnose because it hides itself by camouflaging its body in the color of the fish.

One of the symptoms apparently seen in an infected fish is rubbing its body against the hard decors or sides of the tank.

Camallanus Internal Worm

Is one of the most common parasites in guppies. It can reach 0.8 inches in length, extending out of its anus, brown or orange in color and moving like worms.

There is no definite cause or source about where this parasite comes from, but most of the observed cases are found in guppies raised in outdoor ponds and fed with live organisms like Cyclops.

Protozoan Guppy Disease

This disease can be harmful to any kind of fish. The protozoan parasites hook to the gupppy’s skin and slowly enters the body until they reach its bloodstream.

Protozoan parasites usually comes from unheated tanks with bad water conditions.

Treatments for Guppy Fish Parasitism

Given below is a detailed list of treatments for various forms of guppy fish diseases.

Treating Flukes

Treat the whole aquarium with it if diagnosed early and avoid adding new fish without observing them in quarantine.

Treating Ich/Ick

Slowly raise the tank water’s temperature, and then add the medication for the fish or aquarium salt with a ratio of one teaspoon to a gallon of water measurement.

Keep doing this for about 4- 7 days before slowly decreasing the temperature back to normal. Then do a partial water change of about 70 percent by siphoning (placing a bent tube with one end longer used to gradually draw off liquids).

Treating Hexamita

The recommended treatment for this is administering Metronidazole either as supplementary food or if the fish is not eating, administering it through a bath treatment.

Dosage for metronidazole is usually around 10 milligrams per gram of food, for 5 consecutive days, although you should consult a professional for your fish’s specific case.

Treating Velvet/Piscioodinium

This can be treated early with copper medication. But make sure to administer it to affected fish in a separate tank, as it is deadly to other creatures such as snails and shrimps.

Copper can’t be washed out from a tank, so it is better to use disposable containers during the treatment process.

Turning off or lessening light fixtures of the tank can be a big help in completely curing the disease. Once the fish is symptom-free, you can go back to performing 70-90% water changes.


The best thing to do is to grip the infested fish and remove the worm from the occupied area form its anchor head using tweezers while taking them to quarantine.

Dunk it in a bucket of water to aspirate the bleeding area while removing as many worms as you can. After removing all the possible number of worms therein, treat the fish tank with either potassium permanganate (dip or bath for the fish) at 100mg per 2.5 gallons of water, formalin dip 2-4 ml per 2.5 gallons of water for about 30 minutes.

The fish may go dizzy with these solutions in the water so it should be removed from it immediately. Aquarium salt 1-2 tablespoons, when added to the tank’s water, may help prevent further infections after leaving the guppies a gaping wound. Antiparasitic feeds (such as Disco-worm, Fluke tabs, and Clout) may also help.

Treating Fish Lice

It can be treated effectively by using a water-soluble insecticide called Dipterex (Dylox neguvon) but be sure to accurately follow the recommended dosage as it is acutely toxic to fish.

The dose should be 1 part dipterex to 1 milliliter to 790-1320 US gallons of water.

Actually, fish lice drop off after sucking blood from the fish within two hours so after falling off, bathe the fish with 2 teaspoons non-iodized salt per gallon of water for a couple of days.

But if possible you can manually remove the bigger lice using tweezers or dabbing them with cotton buds dipped in a 50/50 solution of kerosene and turpentine.

Just be careful not to get any of the solution to their eyes, gills, or mouth. And to prevent it, sterilize everything you put in your fish tank or pond, especially the plants.

Treating Protozoan Guppy Disease

Partial water changes with heating can prevent this. Malachite Green or formalin solution can cure this disease if diagnosed early, and for the advance stages Copper based medicine such as Seachem Cupramine should be used.

Other Guppy Fish Diseases

Some other diseases can harm Guppies as well. Along with stressful factors that weaken their immune system and their sudden adaptation to a new habitat in captivity/domestication. Here are the most commonly diagnosed diseases in fish with their certain treatment or home remedies.

Fin and Tail Rot

An infection usually caused by a bacteria or fungus that grows on the nipped fins, or sometimes by ammonia burns or poor water quality.

Their fins and tail cause difficulties in swimming for the fish. It is important to diagnose first what causes the rotting (bacterial infection or fungus) to know which treatment system should be administered.

If the fin or tail is not damaged but has a visible sign of mild rotting, it might be caused by bacteria. But if they are damaged and severely rotten, it is caused by fungus.


Separate the affected fish to quarantine to treat it individually. For bacterial infection, use water-soluble antibiotics such as Tetracycline, Maracyn, Maracyn 2, or Seachem Paraguard.

For fungal infection, medications such as Erythromycin, Trimethoprim, Sulfamidine, or Minocycline can be used for severe cases. If you don’t want to use synthetic treatment drugs, you can prevent it by adding 1-2 drops of Tea Tree oil or 1 ounce of sodium chloride (tonic salt) per gallon of water. And of course, keep your tank water’s pH level and conditions stable.

The pH level should be around 7-8 and the ammonia, and nitrates should not exceed more than 40 ppm.

Columnaris and Mouth Fungus-

Also known as “cottonmouth”, it looks like a fungal infection, but in fact, it is caused by a bacterial colony. It is highly contagious affecting more female guppies than males and can wipe out the entire guppy fish population in the tank if not treated the right away.

The bacterial colony usually forms mostly on their mouth or middle area or their body, causing difficulty in swimming, loss of appetite and eventual paralysis of the body.


As soon as the symptoms are seen, start treatment immediately using Maracyn antibiotics or formalin (add 2-4 ml per gallon only).

Start adding aquarium salt 1 teaspoon per gallon of water with a 50% water change and leave it there until the fish are cured, or use potassium permanganate baths for your fish for 30 minutes (do not exceed dosage of 10 mg per liter of water for each bath, as this is a powerful oxidizing chemical that might burn your fish).


This is also caused by a bacterial infection which may come from feeding them too many bloodworms or prolonged, heightened stress levels. Distinct symptom include severe swelling, discoloration and sometimes raised and distorted scales that look like spine cones.


Usually, this disease cannot be treated because the bacteria inflicts damage to the internal organs of the fish rapidly, so by the time the symptoms begin to manifest, there is no remedy until the fish dies, unfortunately.

Just prevent the disease by providing your guppy with a variety of high quality and healthy food and always ensure good water quality.


Use antibiotics such as Maracyn 2 or API Furan 2 for treatment, then do water changes as often as you can, to at least prolong its survival.

Popped Eyes

The cause of this fish disease is still unknown, making it hard to treat. It can be secondary to any bacterial infection, fungus, dropsy, internal parasites or tuberculosis as a symptom. It may not be deadly, but it can cause blindness.


The popped eye isn’t curable because the cause is still unidentified. All you can do is to prolong the guppy’s life because administering treatments might harm it more than actually help.

Swim Bladder Disorder

This is usually caused by stress like moving from shallow to deep water or unstable water parameters such as high ammonia levels. The Swim Bladder is an internal organ which is filled with air that controls the buoyancy (ability to float) of the fish keeping its current water depth and balance while swimming.

If the fish is sick, initial symptoms may include floating at an angle. If there is inflammation in the swim bladder, the fish belly gets swollen.


Swim bladder disease can be cured by not feeding the fish for 3 days straight before feeding it cooked peas.

Fish Tuberculosis

This disease is caused by a certain myobacterium. Symptoms include appetite loss, discoloration, fin and tail rotting, hollow-belly, ulcers on the body or around the anus. Fish tuberculosis makes the fish go inactive and die slowly.

Tuberculosis in fish has no cure and can be passed on to the other fish if they consume its dead body, so once there is a casualty remove the cadaver immediately. Be careful with dealing with a fish (live or dead) infected with tuberculosis as it can easily spread to human beings. Make sure that you use gloves while touching the fish and the water.

Related Questions

Are Guppies sensitively susceptible to parasites or contagious diseases? Yes, most specifically if they suffer too much stress!

Can we find a remedy for Guppy diseases in our kitchen? Yes, you can use salt, as slight water salinity is intolerable to some parasites.

Can fish diseases be passed to humans? At times, yes, like fish tuberculosis. But most of the rest would stay limited to affecting fish.


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