Fish parasites: helminths parasitizing sea and river fish

Fish parasites are dangerous organisms that can severely compromise human health. According to statistics, 75% of the entire world catch contains eggs of parasites, it is often impossible to see them with unarmed gas and it is possible to determine that the fish is infected only with the help of a microscope. Nevertheless, fish is a very valuable and useful product for the human body, therefore, you should not refuse to eat it, especially since not all helminths in fish are dangerous for people. In addition, with proper preparation, you can protect yourself and your loved ones from negative consequences. It is important to know fish worms - how they look (if you can see them), at what temperature parasites die in fish, how to properly prepare a product in order to prevent pests from entering the human body. Signs of specimen fish

Which fish have parasites

People often wonder if there are parasites in sea fish. For many it will be a discovery, but helminths are found not only in freshwater fish, in sea fish and other seafood there are also dangerous worms. In this case, a parasite can enter the body, which, in principle, does not live in this type of fish. This happens as a result of the feeding of large fish with smaller fish. If you follow safe cooking techniques from seafood, all parasites die, and the dish becomes absolutely safe. Only those who like to enjoy rolls, sushi and other treats that are prepared without heat treatment of the product are at risk. They are threatened with anisakids, which will cause problems with the gastrointestinal tract, and subsequently provoke a stomach ulcer. It will take a lot of time, effort and money to get rid of the parasites and diseases that they caused, is a piece of the roll worth such sacrifices? Parasites in pollock are Chinese fluke, Siberian fluke, broad tapeworm and some others. In red fish: pink salmon, salmon, chum salmon, there is a broad tapeworm, roundworms, feline fluke, phylometroidosis and others. Solitaire in fish

Fish parasites

There are also enough parasites in river fish, most often helminths can be found in grayling, it is not expensive, which means it is in demand among the population. Having cut the grayling, you can often see the white-glazed in it. Often, nematodes can be seen in the liver of crucian carp, helminth larvae look like small balls, and it is quite easy to see them. However, in freshwater fish, you can often find worms that, although they look like parasites, are not such - they are freshwater leeches. With sufficient heat treatment, all freshwater fish parasites die. Parasites in river fish: Chinese fluke, trematodes, tapeworm, broad tapeworm, plerocecloids and others. It is impossible to unequivocally answer the question in which fish there are no parasites, we can only say that helminths are less common in fish living in the sea and even in those of them that swim in very cold water. However, it is impossible to name the type of fish that is not susceptible to helminthic invasions.

General classification of worms

Infectionists divide parasites in fish into conditionally safe for humans and dangerous. Conditionally safe include:

  • Helminths . Almost all types of helminths parasitizing in fish do not cause anything other than an eating disorder in humans. There will be no danger at all if you remove the fish intestines before preparing the dish and wash the carcass thoroughly. Further, the fish should be well thermally processed. In this case, you will get a tasty and healthy dish that will be completely safe.
  • Cystidicolafaryonis . This parasite is most often found in smelt, a fish of the salmon family. It is not dangerous for humans, but heat treatment must be carried out at the proper level.
  • Schistocepharmos in most cases infect carp, this parasite is not dangerous for humans, however, if pets become infected with them, this will lead to serious consequences, therefore, after cleaning the fish, the insides must be well disposed of. best to bury.
  • Trienoforusnodulosus is often found when cutting burbot, but it can also parasitize in other species. In humans, it cannot cause any problems if the fish is thermally processed well.
  • Philometra parasitizes inside carp. It poses a great threat to the inhabitants of freshwater waters, but is safe for humans.

Parasites in fish are dangerous to humans:

  1. Diffillobothriumdendriticum . Found in freshwater bodies of water. The fish for this parasite is an intermediate host, after the larvae enter the human body, they grow into a worm 1 m long.
  2. Diphyllobothriumalatum lives in the gills of burbot, perch and pike. In the human body, the larva develops into an adult up to 50 m long.
  3. Tapeworm in fish is also dangerous to humans. It can be found in different types of fish - herring, bream, roach, blue bream, pike and many others.

Wide ribbon

Wide tapeworm is an insidious species of helminths, the largest parasite living in fish. Basically, freshwater carps and salmon fall prey to this type of parasite. Fish become infected by eating contaminated shellfish. The body of the worm resembles a long ribbon, hence the name of the species.

  1. A larva moving independently in water (keracidium) and two parasitic stages (procercoid): in the cavity of mollusks, crustaceans, and then in fish - this is the life cycle of tapeworms.
  2. The tapeworm has oval yellow eggs. They develop in fresh water reservoirs. In a favorable environment (if the temperature is not lower than 15 ° C), the embryo begins to develop. In colder water, it is viable for up to six months.
  3. The crustaceans swallow the larva, and the fish swallow the crustacean or smaller fish. After a month, the larva grows up to 5 cm in the body of the fish.
  4. Helminths fully mature in the last host.

Seliternaya fish

Infected fish have a swollen belly. An autopsy reveals the worm itself, but its larvae cannot be seen without special magnifying devices.

They live: The last owner of the tapeworm can be a person if he eats infected fish that has not undergone prolonged heat treatment. When frozen, the tapeworm larvae survive. If tapeworms were noticed when cutting fish, then it is advisable not to eat it, since there is a high probability of the presence of larvae in the meat. It is better to refuse such fish.

Cat Fluke

This is how flatworms are called - flukes . The parasites are small (their length does not exceed 18 mm), pale yellow in color. Helminths develop first in a mollusk in the body and fish of the cyprinid family. Last hosts: humans and animals, such as bears, which feed on raw fish. The cat fluke is viable for at least three decades, or even more, inhabiting the human body. The worm got its name from the cat, in whose liver it was first discovered at the end of the 18th century. fluke has female reproductive organs and male ones. Between them is a uterus full of small eggs. Worms are called suckers because of the suckers with which they cling to the walls of the owner's organs. Cat fluke

The feline (Siberian) fluke develops in several stages:

  1. Feces in which the eggs of infected animals end up in the aquatic environment.
  2. They settle in the body of mollusks, develop there, grow for several months (up to 10). Then they leave the owner and find a new one.
  3. With the help of the tail, the larvae move freely in freshwater reservoirs, remain viable for up to 12 months.
  4. They penetrate through the skin into the fish organism, thus losing their tail, overgrowing with a shell.
  5. Together with infected fish, worms enter the human body if the fish meat has not been sufficiently processed.

In humans, fluke settles in the organs of the gastrointestinal tract, such as the pancreas, bladder, and liver. A person becomes infected with helminths by eating sick fish: bream, rudd, roach. Infected people may not be aware of the presence of feline fluke in their bodies. Trematodes belong to the class of flukes with a flat, leaf-shaped body covered with a shell. Trematodes are attached to the nipples (those that live in the bloodstream do not have them). Trematodes have a difficult life cycle. The intestines of mammals, fish, birds are the place of their parasitism. At first, like other worms, they choose molluscs; then their owners are fish (sometimes there may not be a second intermediate owner).

  1. Adult parasites live in the intestines of fish-eating birds: herons, gulls and others. Bird excrement with worm eggs ends up in the water.
  2. Under favorable conditions, larvae emerge from them. With the help of cilia, they move, find the liver or gonads of the mollusk, and get inside.
  3. The larvae throw off their cilia, become a motionless load that grows. It reaches a certain stage of development, bursts, new larvae, similar to worms, emerge from it. They have no tail or genitals.
  4. They get rid of molluscs, move through the water, where they enter the fish's body, settle in any of the organs (even the eyes), losing their tail.
  5. By eating such fish, birds become infected. And only in them in the body parasites reach sexual maturity, lay eggs, repeating the life phase.

Belt worm

Remnets is the longest tapeworm (it can be more than a meter in length), parasitizing in fish. People call the yellowish-white parasite the tapeworm. An individual who has not reached sexual maturity lives in a fish, the fish is an intermediate host. The last owner of helminths is birds that eat fish. It is in their intestines that the parasite will become sexually mature, ready to reproduce.

Most often, the victims of helminths are bream, but parasites do not disdain:

Living in fish, worms feed on its juices, grow, squeezing fish organs, which is why their work is interrupted. Often, fishermen watched bream swim on the surface of the water, unable to go to the depth. The parasite is to blame. Developing in fish, it damages its swim bladder. You can eat such fish, you need to thoroughly clean it, rinse it, cook it at a high heating temperature. It is possible that the taste of sick fish is inferior to healthy ones, since it could not fully feed and develop. Solitaire in fish

Philometra is a parasite that lives under the gills of fish of the carp family, and can live under the scales. Thin worms no more than 15 cm long, red. The presence of parasites is indicated by black specks on fish scales. Red parasites occur: The meat of the infected fish falls apart and tastes unpleasant. So that parasites do not harm human health after eating sick fish, it is pre-cleaned of worms, washed well, and cooked at a high heating temperature. Worms are the most dangerous for humans, despite their small size (up to 5 cm long). They live in marine life: Sometimes parasites are called herring worm. Anizakids live in cod, but they are smaller. Worms have the same life cycle as other worms. But not only adults can destroy their master, but even the larvae. They bite into the intestinal walls of their owner, causing mechanical damage, destroying the work of organs. From their vital activity, toxins accumulate, poisoning the body. Anisakids in fish

Diseases of the person who ate the contaminated fish

Eating contaminated fish can put people at great risk to their health. Infected fish, improperly cooked, can cause dangerous diseases, even fatal ones.


Diphyllobotriasis causes wide tapeworm. It has been a parasite in the human body for at least 10 years, but there are known cases of helminths in the small intestine for up to 40 years. During its life, pieces of the worm come out in the toilet. Treatment of diphyllobotriasis

People become infected with diphyllobothriasis if they eat raw or poorly cleaned and cooked fish. Sometimes it is difficult to identify the disease. It proceeds in different forms, but large parts of the parasite's body are always visible in the feces of a person. The patient may feel dizzy, feel weak, infrequent pain in the abdomen. The disease can manifest itself 2 months after infection. Moreover, children get sick more severely than adults, although the clinical picture is the same. Diphyllobothriasis affects the human body:

  • mechanically;
  • allergic, toxic;
  • neuro-reflex.

Ulcers and atrophy are formed in the places of attachment of the helminth in the intestine. The work of the gastrointestinal tract is disrupted, anemia develops. The disease is detected when visiting a doctor, in the course of laboratory tests, blood tests and patient complaints. When the correct diagnosis is made, the person fully recovers during the treatment started. The causative agent of the disease is a flat worm, the length of which is no more than 20 mm, and the width is up to 4 mm. Parasites live in the liver, bile ducts, pancreas in animals and humans. If you do not start treatment on time, the disease becomes chronic. The clinical picture is similar to the manifestation of opisthorchiasis. The clonorch worm or Chinese fluke is the causative agent of the disease. In the first half month after infection, the disease does not make itself felt. Then symptoms appear, depending on the severity:

  1. A person has general weakness, diarrhea, abdominal discomfort. This is a mild form of the disease.
  2. Poor appetite, stomach ache, fever, the patient is losing weight for no reason - signs of a moderate form of the disease.
  3. Sharp pains in the right hypochondrium, high temperature, the liver and spleen increase, become inflamed, the skin becomes covered with a rash, as the human body is poisoned by the waste products of parasites. Symptoms indicate severe illness.
  4. Diseases of the liver and pancreas develops: pancreatitis, cholecystitis, cholelithiasis.

To prevent the dangerous disease of clonorchiasis from acquiring a severe chronic form, it is necessary to consult a doctor in time, who will prescribe a full-fledged treatment. The disease caused by the larvae of the ligature is ligulosis or tapeworm. Doctors consider the disease not too dangerous for people. The person feels mild malaise, discomfort, loss of appetite. It is necessary to consult a doctor who will prescribe a course of treatment for helminths. Parasites are visible to the naked eye. Contamination can be avoided if the fish is cooked at high heat, cleaned thoroughly and rinsed.


The causative agent of the disease is a trematode. She lives in the small intestine. The clinical picture of the disease:

  • violation of the digestive process;
  • allergic manifestations;
  • heaviness in the abdomen, rumbling, discomfort, pain;
  • decreased appetite, weight loss.

In children, the disease is more severe. Nanofietosis is completely cured by anthelmintic therapy. The main thing is to seek help from a specialist.


Opisthorchiasis is one of the most dangerous diseases caused by the feline or Siberian fluke. A flatworm or fluke lives in the pancreas, bile ducts. It is sometimes found in the liver and gallbladder. Worms and larvae enter the human body not only after eating sick fish. Even the one who cleans an infected carcass is at risk, since the larvae are small and difficult to see.

  1. The disease has a latency period of 21 days. The initial phase of the disease proceeds without signs. Feel weakness, malaise, increased sweating, abrupt increase in temperature.
  2. Later, the infected person constantly has a headache, abdominal discomfort, which develops into pains that become more frequent and stronger. Then the desire to eat disappears, nausea, loose stools or constipation.

With the correct diagnosis and treatment initiated, the person will fully recover. It is undesirable to delay the visit to a doctor in order to avoid complications that can lead to serious consequences, such as cirrhosis of the liver. Opisthorchis Felineus

Fish species most susceptible to infestation

Not all fish species, both marine and freshwater, are equally susceptible to infection by various parasites. The most susceptible species susceptible to parasite infestation include:

  • Carp . Living in the middle zone, this common inhabitant of various reservoirs rarely becomes the cause of infection. Living within the Far East, this fish often becomes the object of infection with clonorchiasis.
  • Yazya . It is believed that the ide is an omnivorous fish, therefore it is most susceptible to infection with the Siberian fluke, which can cause many dangerous ailments.
  • Bream . Found in the middle lane, as well as in warmer regions, this fish is a carrier of ligulosis.
  • Perch , which, if eaten without careful processing, can become infected with ligulosis and diphyllobothriasis. Diphyllobotrium latum larvae are found in the gills of fish. This parasite poses a serious health hazard.
  • Lin . As a rule, this fish lives in reservoirs with dense thickets of aquatic vegetation, as well as a muddy bottom. In such conditions, the cat fluke develops well, which can cause such an ailment as opisthorchiasis.
  • Pollock . This seafood, which is often found on store shelves, can infect a person with anisacidosis, a very dangerous disease.
  • Flounder . Many helminths can settle in this fish, so it is generally not recommended to eat it without heat treatment.
Note to the hostess! Cooking dishes from the above fish species requires high-quality heat treatment. These types of fish are not recommended to be consumed lightly salted, and even more so, raw.

How to protect yourself from parasite infestation

Knowing that fish can contain various parasites, you should adhere to the cooking technology, subjecting the fish to heat treatment. These technologies include:

  • Cooking.
  • Fry.
  • Hot smoking.
  • Deep Ambassador.
  • Deep freeze.

If the fish is cooked for at least 20 minutes, then any types of parasites will die in it. If the fish is fried, then this is another quite effective way to get rid of parasites, since the temperature regime is higher than during cooking. Hot smoking also allows you to neutralize parasites, but the duration of processing should not be less than 2 hours. In addition to temperature treatment, there are two more options that allow you to protect a person from infection with helminths - these are deep salting and deep freezing. Salt destroys all types of parasites within 2 weeks. If large fish is used for salting, then the processing terms should be increased. You can also destroy parasites with the help of deep freezing, at a temperature of -40 degrees. In such conditions, the parasites die within 24 hours. Before such a technological procedure, the fish is thoroughly washed under running water. As you can see, there are enough ways to disinfect fish, so it is not problematic to use any of them. Recently, it has become fashionable to eat fish without proper heat treatment, since most of the beneficial components, such as minerals and vitamins, are retained in such dishes. But then you need to be 100 percent sure that the fish meat does not contain parasites, otherwise healthy food will turn into serious health problems over time.