Identifying Those Tiny White Worms in Your Aquarium

What Are These Tiny White Worms in My Fish Tank?

The Spruce / Kaley McKean

Any aquarium hobbyist that has noticed tiny white worms in their fish tank likely has one of two issues they to address. The more common worm, the Detritus Worm, is naturally found in many aquariums, and any overpopulation can be fixed with proper maintenance. The less common Planaria worms are a more complex problem.

Before making any changes to your tank, be positive about which white worm you’re dealing with. Only then can you know if the careful use of a de-wormer or just a good cleaning is what is required. Misinformation about the correct use of de-wormers and overuse of de-wormers often leads to harming and killing of fish by mistake.

Detritus Worms

Detritus Worms are annelid worms; this is the phylum that includes the segmented worms such as earthworms and leeches. They look like thin, pointy, white-brown strings that wiggle through the water and between pebbles. Detritus Worms are detritivores, meaning that they only eat decomposing plant and animal waste material; they will not harm your fish.

It is not uncommon for an aquarium to have Detritus Worms, as they can be introduced through a variety of means. For instance, they may have come in with a new fish or plant, and may even have been present in any gravel swapped in from another tank.

Quite often, Detritus Worms are not even seen. They tend to live in between the pebbles of gravel where they eat the debris left over from feeding or deposited by your fish. You may only notice them when they get sucked into a tank cleaning vacuum. Detritus Worms may actually be a beneficial symbiotic organism in your tank system as they help to keep your tank clean.

Removing Overpopulated Detritus Worms

When you see Detritus Worms coming out of the gravel frequently, that means that a problem has occurred in your tank. It can be shocking when your normally clean water becomes filled with hundreds, if not thousands, of tiny white worms, especially if you don’t know what caused the bloom. But it is important to not treat a Detritus Worm issue with de-wormers or any medications; these will not take care of the problem and may cause an inadvertent fish kill.

An overabundance of annelid worms can occur when tank maintenance has been lacking. Insufficient cleaning schedules or overfeeding of fish can cause Detritus Worms to reproduce rapidly and get out of control. Reduced dissolved oxygen or pH levels that are too low (both are symptoms of unclean water) will cause Detritus Worms to seek more oxygen. The worms will flee their gravel home, traveling up the water column toward the surface.

Worm removal begins by giving your tank a thorough cleaning. Use a gravel vacuum and change the water to remove the majority of the Detritus Worms and also their food sources. Secondly, be sure to check your filtration system for any issues. As a proper oxygen level is required to keep worms at bay, the well-maintained filtering system is essential to their prevention.

Going forward, regularly clean the substrate, review your feeding practice, and assure that your tank is not overstocked with fish. Ensure that they are getting enough proper food without creating too much waste.


Planaria (singular, planarium) worms are not as common as Detritus Worms, but they are much harder to remove. These are flatworms; most are brought in with pond plants, especially if acquired from a local pond or natural water source. If you’ve introduced those recently and then noticed white worms, chemical treatment is required.

Planaria are flatworms in the class Turbellaria; they are found in both freshwater and saltwater environments the world over. They are quite small, but if you can examine them closely enough, you’ll see eyespots as well as protrusions on both sides of their widened heads. Quite often, these are the worms that are crawling across the glass inside an aquarium.

They are related to flukes and tapeworms but are evolutionarily more ancient than the Annelid Worms (which are not «flat» worms). These ancient worms are asexual animals, meaning they can reproduce without mating. Even after cutting one into pieces, you’ll have a new worm for each piece.

What makes these worms problematic is that they are both scavengers and carnivores. Although they will not harm your healthy fish, they love to feast on fish eggs and therefore are dangerous if you are breeding egglaying fish. They may also prey on gills and eyes of weakened adults.

Eradicating Planaria

If you do indeed have a Planaria problem, it’s a serious issue. While Detritus Worms can number in the thousands, Planaria troubles are often caused by just a few flatworms that are difficult to locate. This is why getting rid of Planaria requires chemical treatments. But as chemicals may also harm your fish population, you’ll want to be absolutely sure of the presence of Planaria before seeking the solution.

Thoroughly research each of the following chemical products before using them to predetermine if they will be safe for your species of fish. Vulnerable invertebrate species like snails and shrimp should be removed. Sharks, silverfish, lionfish, piranhas, bottom feeders, and certain scaleless or Metynnis fishes may also be sensitive to some worm eradication treatments. Any worms on these tank residents must be removed manually with blunt tweezers or a quick salt or freshwater dip.

With all de-wormers, be sure to use the precise recommended dosage from the manufacturer. Too much can cause a fish kill. Also, these products require strict adherence to safe handling instructions. The recommended de-wormers for killing Planaria include:

  • AAP Clout Parasite Treatment (or any product containing Trichlorfon) is a neurotoxin and this seems to be the most effective.
  • API General Cure may be less effective but is an alternative to Clout.
  • Levamisole HCI is a general de-wormer, though it should be used with caution and may not be as effective as other options.

All of these products can be found at American Aquarium Products & Supply, which also has information about their safe handling and application.

Intestinal worms in humans and their symptoms

Intestinal worms, or parasitic worms, are simple organisms that feed off the human body. Many people recognize the more common varieties, such as tapeworms and hookworms, but may be less aware of the others.

Intestinal worms can cause many symptoms in the body, some of which are similar to the symptoms of other gut disorders. A quick and thorough diagnosis is crucial in each case to avoid complications.

Doctors may use antiparasitic medications or other treatments to help get rid of the worms. Although intestinal worms may seem scary, most people respond well to treatment.

In this article, we take a look at the different types of intestinal worm and the symptoms that they can cause. We also examine how people can get intestinal worms and what the treatment involves.

Each species of intestinal worm may cause different symptoms, and the symptoms may also vary from person to person.

However, some common signs and symptoms of intestinal worms include:

In some cases, the person may start passing segments of the intestinal worm in their stool.

In rarer cases, the intestinal worm may lead to severe blockages in the intestine, making it difficult for the person to have a bowel movement.

There are many different types of intestinal worm that can affect people. Below, we look at some of them in more detail.


A tapeworm is a type of flatworm that lives in the intestine, where it attaches itself to the intestinal wall. Most people with tapeworms experience either no symptoms or very mild symptoms.

There are a few different types of tapeworm. Some tapeworms live in water, and drinking unclean water may allow them into the body. Other tapeworms live in meats, such as beef or pork, and ingesting unclean or raw meats may expose the person to them.

Tapeworms are flat and tend to be long, usually between 3 and 10 meters depending on the type of worm. The Centers for Disease Control and Prevention (CDC) estimate that there are fewer than 1,000 new cases of tapeworms each year in the United States.


A hookworm is a worm that usually enters a person’s body through unsanitary soil. The name of the worm describes the way that one end of its body tapers off into a needle or hook shape.

The CDC state that, according to estimates, 576 to 740 million people in the world have a hookworm infection.

Hookworms take up space in the small intestine, where they lay eggs, which pass out of the body through the feces.

When the eggs hatch, the larvae can potentially enter through the skin of another person. People are at risk if they come into contact with the fecal matter or with soil containing contaminated feces as fertilizer.

Most people with a hookworm have no symptoms. Some people may show typical gastrointestinal symptoms, and this may be more common with first-time infections.


Flukes are another type of flatworm. Flukes may be more common in animals, although it is possible for humans to contract these parasitic worms as well.

Flukes are small and have a rounded leaf shape. Humans get them by accidentally eating or ingesting them, either in drinking water or freshwater plants, such as watercress.

Once inside the body, adult flukes occupy the bile ducts and liver.

Some people do not have any symptoms, but others may experience symptoms months or even years after first ingesting the parasite. These people may experience inflammation of the bile ducts or complete blockages. They may have an abnormally large liver or unusual readings on a liver test.


A pinworm is a small, thin roundworm that is about the size of a staple.

Pinworms are relatively harmless and sometimes live in the colon and rectum of humans. Someone who has the worms can pass them onto someone else through direct contact or by sharing a contaminated object with them.

Pinworms commonly cause itching around the anus, which can be severe enough to make sleeping difficult. Symptoms appear during the night as this is when the female pinworms crawl out of the anus to lay their eggs on the surrounding skin.

Other symptoms are usually mild, and many people do not experience any.


Ascariasis is similar to a hookworm, although it is only a few inches long. It lives in contaminated soil, so it only enters the body when people ingest the eggs. Inside the body, this worm lives in the intestines.

People with an ascariasis infection often show few to no symptoms. However, severe infections may cause intestinal blockages or impair growth in children.


Trichinella worms are another type of roundworm that may pass to humans who eat undercooked or raw meats that contain the live larvae. The larvae then grow in the intestines.

On reaching their full size, the Trichinella worms may leave the intestines and live in other tissues, such as the muscles.

Symptoms vary with a trichinosis infection. In addition to common gastrointestinal symptoms, some people may experience:

  • chills
  • muscle aches
  • joint pain
  • swelling of the face or eyes

Heavy infections may cause breathing or heart problems or make it difficult for the person to move. Very severe cases may lead to death.

Trichinella infection is rare in the U.S., but it is more likely to affect people who eat wild meats, such as bear, pork, or seal.

As a 2016 study notes, over 3.5 billion people around the world have an intestinal parasite infection.

The vast majority of these infections occur in developing countries where sanitation is poor. However, intestinal worms are still possible in developed areas.

Some people may be more at risk of contracting an intestinal worm. These people include those with a weakened immune system, such as older people and people living with HIV.

Pregnancy does not increase the risk of getting intestinal worms, but intestinal worms may pose a more significant health risk for people who are pregnant. Some antiparasitic medications may not be safe during pregnancy.

Anyone who is pregnant and has an intestinal worm should work closely with their doctor throughout their treatment.

Doctors may order several different tests to help them diagnose intestinal worms. These tests may include:

  • fecal tests to check for signs of infection
  • blood tests to detect some types of parasite
  • colonoscopy, which uses a thin camera to check the bowel for parasites
  • imaging tests to check other organs for signs of damage from the parasite
  • tape tests

A tape test involves placing a piece of tape over the anus as the person sleeps to check for signs of eggs.

Anyone who suspects that they have an intestinal worm should see a doctor.

Although intestinal worms sound a bit frightening, treatment is often straightforward. In some cases, the person may not need any treatment at all. A healthy immune system may be sufficient to manage some types of tapeworm without the need for medication.

In other cases, doctors will use one or more antiparasitic medications to get rid of the intestinal worm.

Doctors will sometimes choose to monitor the person first to see if their body can take care of the worm before moving on to medication. During this period, the individual should report any symptoms to the doctor.

Some signs and symptoms may indicate that further treatment is necessary. These may include:

  • vomiting
  • high fever that lasts for more than a couple of days
  • extreme fatigue
  • dehydration
  • changes to the color of stool
  • blood in the stool

Before commencing a person’s medical treatment, the doctor has to identify the specific type of intestinal worm. The type of worm will determine the best treatment option.

Doctors often prescribe praziquantel (Biltricide) to clear out a tapeworm. This drug paralyzes the worm, forcing it to detach from the intestinal wall. It then helps dissolve the worm so it can pass through the digestive system and leave the body during a bowel movement.

In the case of hookworms, doctors prescribe anthelmintic drugs, such as mebendazole or albendazole.

Triclabendazole may help treat flukes, while pinworm infections often respond well to both over-the-counter and prescription drugs.

Intestinal worms may increase the risk of certain health issues in the body. Some intestinal worms may make it difficult for the body to absorb protein or cause a loss of blood and iron, which could lead to anemia.

Intestinal worms may also affect a person’s ability to pass food through the intestines. This issue could ultimately lead to an intestinal blockage, which requires immediate treatment.

Some types of intestinal worm may also lead to human cysticercosis, which is a potentially serious disease that can damage the eyes and cause seizures.

While it may not be possible to get rid of all possible sources of intestinal worms, it is still essential to take certain steps to avoid them where possible.

One of the more important aspects of prevention is basic sanitation. For instance, people should always wash their hands both before and after using the toilet to avoid possible exposure. Washing the hands before cooking or handling food is also crucial.

Many intestinal worms enter the body through the food that a person eats. As a result, it is essential to follow some safe food practices:

  • Thoroughly cook pork, beef, and other red meats to an internal temperature of 145°F.
  • Always cook poultry, such as chicken and turkey, to an internal temperature of 165°F.
  • Ensure that cooked fish reaches an internal temperature of 145°F.
  • Never eat undercooked or raw meats.
  • Use separate cutting boards for meats and vegetables.
  • Thoroughly wash and peel all fruits and vegetables.
  • Only use clean water.

When visiting a developing country or a place where sanitation is lacking, avoid swimming in sources of unclean water or walking barefoot in areas where contamination with fecal matter is possible.

Many intestinal worms are uncommon in the U.S., largely due to proper hygiene and cooking practices.

Some common worms, such as pinworms, do not pose much harm. In most cases, a thorough course of treatment can help clear up the issue.

However, anyone who suspects that their symptoms come from an intestinal worm should see a doctor as soon as possible for a diagnosis and treatment. Most people respond well to treatment.

What Are Pinworms? How Do You Get Infected?

In this Article

In this Article

In this Article

Pinworms are small, thin, pin-shaped worms that sometimes live in the human colon and rectum. They are also called threadworms. They’re about one-quarter to one-half inch long — about the size of a staple. The females do their work while an infected person sleeps: They leave the intestine through the anus and deposit their eggs on the surrounding skin.

How Do You Get Them?

By accidentally swallowing or breathing in their eggs. You could eat or drink something that’s contaminated with them and not know it. The eggs can also live on surfaces like clothing, bedding, or other objects. If you touch one of these items and then put your fingers in your mouth, you’ll ingest the eggs.

About a month later, the eggs hatch in your intestines and mature into adult worms. Female pinworms move to your anus area to lay their eggs. This causes anal itching. If you scratch the area, the eggs cling to your fingers and get under your nails. If you touch other surfaces or objects, you could spread the worms.

Are They Contagious?

Yes. Pinworm infection occurs most often in school-aged children. It’s also easily spread to family members and caregivers.

People who live in crowded spaces, like institutions, have a higher risk of getting pinworm infections.

What Are the Symptoms?

Most people who are infected don’t have any. If you do, they might include any of the following:

  • Anal itching, especially at night
  • Restless sleep
  • Itching of the vaginal area — if adult worms move to the vagina
  • Feeling irritable
  • Abdominal pain that comes and goes

Talk to your doctor if you have severe anal itching — especially at night.

Most of the time, pinworm infections don’t cause serious problems. In rare cases, and especially if you have a lot of them, the pinworms can travel from the anal area up the vagina to the uterus, fallopian tubes, and around the pelvic organs. This can cause inflammation of the vagina — what doctors call vulvovaginitis.

Tape Test

If you, your child, or someone in your household has symptoms of pinworm infection, call your doctor and ask about the tape test. Simply take a clear piece of tape and press the sticky side to the skin around the anus. Do this as soon as you or your child wake up — before you use the bathroom, shower, or get dressed. The pinworm eggs will stick to the tape.

You’ll need to repeat this test three days in a row, then take all the pieces of tape to your doctor. He’ll view them under a microscope.


What’s the Treatment for Pinworm Infection?

You’ll need to take medications that kill the worms.

Your doctor may recommend an over-the-counter treatment like pyrantel pamoate (Reese’s Pinworm Medication, Pin-X). He might also prescribe medication to everyone in your household to prevent infection and re-infection.

The most common prescription medicine for pinworms is albendazole (Albenza). You might have mild stomach upset while you’re taking it. And, you may need to take at least two doses to get rid of the worms completely.

For best results, the infected person and everyone in your house (including caretakers) should be treated at the same time.

How Can I Prevent Pinworms?

Pinworm eggs can live on hard surfaces and in clothes and bedding for two to three weeks. In addition to your regular household cleaning, you’ll want to do the following things to stop the spread of these pests:

  • Pinworms lay their eggs at night. Wash your anal area in the morning to reduce the number of eggs on your body. Shower to prevent possible re-contamination in bath water.
  • Don’t bathe with anyone or share towels during treatment and for two weeks after final treatment.
  • Change your underwear and bed linens each day. This helps remove eggs.
  • Wash bedsheets, nightclothes, underwear, washcloths, and towels in hot water to kill pinworm eggs. Dry them on high heat.
  • Don’t scratch your anal area. Trim your child’s nails so there’s less space for eggs to collect. Discourage nail biting.
  • Wash your hands with soap and water after using the bathroom, changing diapers, and before handling food. Teach your kids to do the same.


Sub Navigation


Find an Agency

Top FAQs


News and FAQs

Top FAQs

I Want To

Main Content


Fish Parasites & Diseases

Fish, like any animal, are exposed and susceptible to a wide range of diseases and parasites. In fact, it is unusual to find a fish completely free of disease organisms. It is normal to see a few dead fish from time to time. These fish usually die as the result of natural causes. Severe losses of fish due to disease organisms are rare in a natural environment. Most severe losses occur when fish are stressed due to unfavorable conditions, such as poor water quality.

Disease problems are most noticeable in the spring when fish are in a weakened state after winter and during the stressful spawning period. Also, as the water warms in spring, living conditions are better for growth of disease organisms.

There are no practical, and few safe methods, for treating disease problems in ponds. Disease outbreaks in ponds simply must run their course. Prevention or repression of disease is best accomplished by stocking only healthy fish from reputable sources and by maintaining a favorable pond environment.

With the exception of the broad fish tapeworm, fish parasites are not harmful to humans. Proper cooking destroys parasites, including tapeworms. Some of the more common parasites and diseases are described below.

Black-spot disease

These parasitic flatworms appear as tiny black spots on the skin, fins and flesh of fish. No method of control is available for the elimination of this problem. This organism does little harm to the fish. The main problem associated with black-spot is the unsightly appearance it may cause. Skinning infected fish will remove most black spots.

The life cycle of the parasite is quite complex. A fish-eating bird (typically a great blue heron or kingfisher) eats an infected fish. The black spot or worms are released and grow to sexual maturity in the bird’s intestine. The adult worms pass eggs with the bird’s droppings. When the eggs reach water, they hatch into free-swimming organisms which then penetrate snails for further development. Finally, after leaving the snails they burrow into the skin of fish and form a cyst. The fish surrounds the cyst with black pigment that gives the disease its name. If an infected fish is consumed by a bird, the cycle repeats itself.

Yellow grub

The yellow grub (or white grub) is also a larval flatworm with a life cycle similar to parasites causing black-spot disease. The parasite appears as yellow or white spots in the flesh, often 1/4 inch long. While unsightly, it is harmless to man and in many cases can be removed during the cleaning process.


The most common fungus is saprolegnia and appears as gray-white threads resembling cotton balls growing on fish or fish eggs. Fungus usually occurs as a secondary infection caused by handling, parasites or bacterial attack. There is no practical way to control fungus in pond situations. Fungus rarely causes a fish to die, but can often be found on weakened or stressed fish before they die.

Ichthyophthirius «Ich»

Ich is a large, ciliated, single celled animal (protozoan) that can be positively identified under a microscope by its horseshoe shaped nucleus (center). It is common on warm-water fish, and occasionally found on cold-water fish.

In the early stages of Ich, infected fish usually rub against the pond bottom in an effort to rid themselves of the parasite. This protozoan can be very harmful to fish. Losses due to «Ich» often occur.

The elimination of «Ich» in a pond situation is virtually impossible. Problems resulting from the parasite can be minimized by maintaining good water quality in the pond and by making sure only healthy fish are stocked


Lymphocystis is a viral disease that causes a yellow or white wart like growth on the fish’s body. Lymphocystis subsides naturally only to return, much like a cold-sore in humans. Generally, little harm is done to the fish but the infection is unsightly.

Bacterial Diseases

Bacterial diseases are common in all fish and occur most often when environmental conditions, such as water quality, are not favorable. Inadequate oxygen levels in the pond can stress fish and make them susceptible to bacteria infections. These infections are often associated with spring die-offs in fish ponds. As the water warms during the spring, fish weakened by the winter months are often invaded by harmful bacterial that can cause death. This weakened condition can also be enhanced by frenzied spawning activity that further stresses the fish.

Bacterial losses are one of the most commonly noted causes of fish loss during May and June. No control is available for the treatment of bacterial problems in ponds. Fortunately, bacterial problems rarely reach epidemic proportions in ponds.

No comments

Добавить комментарий

Your e-mail will not be published. All fields are required.