Parasites in Fish and How to Avoid Them

January 25, 2023

Fish is an excellent source of many essential nutrients and a great food to include in your diet. However, fish can also expose you to harmful parasites that can negatively impact your health. Fish, especially raw fish, is a very common source of parasite exposure. These can be fully grown helminths (worms) as well as microscopic larvae or eggs. Single-celled protozoa can also be contracted from consuming raw or undercooked fish.

In this article, we will discuss some of the common parasites in fish and how you can avoid getting infected by a parasite.

What Are Parasites?

A parasite is an organism that lives inside another host organism and sustains itself at the expense of that organism. There are both internal and external parasites. Internal parasites refer to worms and protozoa, whereas external parasites refer to ticks, lice, and fleas—creatures that live on the body rather than inside it. (1)

To learn more about the different types of parasites that can infect humans, read our article "Most Common Types of Parasites."

Types of Parasites Found in Fish

parasites in fish

There are three types of parasites in fish that are of greatest concern to public health: roundworms (nematodes), flatworms or flukes (trematodes), and tapeworms (cestodes). According to the Food Safety Authority of Ireland:

“The most common roundworms that can infect humans are from the family of Anisakidae and include Anisakis spp., Pseudoterranova spp., Phocascaris spp., and Contracaecum spp.

The most common flatworms or flukes involved in human infection are liver fluke worms belonging to the family Opisthorchiidae and some species of intestinal fluke worms belonging to the Heterophyidae and Echinostomatidae families. Human infections caused by fish tapeworm are most commonly caused by the genus Diphylloborothrium.” (2)

These are the most common fish parasites in humans. However, not all of the internal parasites in fish infect humans as well.

Humans can be infected by parasites in freshwater fish as well as parasites in salt water fish. Roundworms are found in saltwater fish around the world, whereas tapeworms are commonly found in coldwater freshwater fish. Flatworms or flukes are commonly found in freshwater fish in warm or temperate waters. (2)

Fish become infected with parasites in a variety of ways. Some become infected from direct contact with other fish, such as contact of the skin or gills with other contaminated fish. This is a more common way that ectoparasites are transmitted.

Other internal parasites in fish often have complex life cycles that sometimes involve multiple hosts. For example, a parasitic worm may attach to the intestinal wall of a fish, which then dispels eggs that are eaten by a shrimp or other species that are in turn, ingested by another fish. With some parasite life cycles, larger marine mammals like sea lions or dolphins can also be involved.

How Do Humans Get Infected with Parasites from Fish?

sushi

Humans can become infected with a parasite by consuming a fish that contains live parasites. While humans may not have been involved in the natural life cycle of the parasite, they can be suitable hosts for a variety of parasitic organisms.

Essentially, we can become infected from eating fish that have parasites in them, which most often happens with raw fish (sushi, for example) or undercooked fish.

Sushi is a very common food source of internal parasites. There is an inherent risk with eating sushi that contains raw fish, though some very skilled sushi chefs are trained to identify and remove parasites from fish. Salmon is another type of fish that commonly contains parasites. With all fish, especially those more known for contamination, it is vital to thoroughly cook the fish to kill any potential living parasites that could result in an infection.

What Health Risks Do Parasites in Fish Pose to Humans?

human parasite infection

If consumed, a live parasite in a fish can inhabit your body and use you as a host organism. This means it will steal nutrients from you, eliminate waste inside you, and reproduce its offspring. Clearly, this is not something you want to happen.

In many cases, people can have parasitic infections with little to no symptoms. In other cases, parasites can cause serious health issues. Some health issues caused by parasites may also resemble other common ailments, making it challenging to diagnose correctly.

Some of the symptoms that parasites can cause in humans include:

Skin bumps or rashes
Weight loss, increased appetite, or both
Passing a worm in your stool
Abdominal pain
Diarrhea
Nausea or vomiting
Sleeping problems
Gas or bloating
Anemia
Aches and pains
Stomach pain or tenderness
Feeling tired/fatigued
Allergies
Weakness and general feeling unwell
Fever
Dysentery (loose stools containing blood and mucus)
Rash or itching around the rectum or vulva

To learn more about parasites, read our article “How to Test for Internal Parasites.”

How Do You Get Rid of Parasites from Fish?

If you have a parasitic infection, you will need to take antiparasitic herbs or medication to kill the parasites, parasite eggs, and parasite larvae. This is best done with a proper parasite detox protocol. It may take several days to several weeks to get rid of a parasitic infection, depending on the severity of the infection.

The best approach is to diligently consume a parasite detox formula according to the recommended directions and to follow an antiparasitic diet as well. Eating antiparasitic foods and consuming antiparasitic herbs will kill the parasites and adequately eliminate them from your body, alleviating the symptoms caused by the infection.

Our Parasite Detox Tonic may help to eliminate the adult, larva, and egg stages of many different species of harmful organisms.† The herbs in our formula are 100% sustainable and wildcrafted, which means no pesticides, preservatives, chemical fillers, or genetically modified ingredients.

How to Avoid Parasites from Fish and Other Food

cooked fish

The best thing you can do is to avoid getting a parasitic infection in the first place. This can be done by always cooking your fish thoroughly and avoiding foods with raw fish (sorry sushi lovers).

While raw meats are a common source of parasite exposure, these organisms can be found in other raw foods, such as fruits and vegetables. For this reason, it is recommended to rinse your fruits and veggies in a non-toxic wash. You can make one of these at home with purified water and key lime juice or buy some natural vegetable washes online or from many natural health markets. Avoid washing them in tap water unless purified, as tap water may also contain harmful chemicals.

If you are traveling, be sure to drink only bottled or purified water, and to always eat cooked food—especially in countries with poor sanitation. You can also take a daily dosage of our Parasite Detox tonic while traveling as a precautionary measure.

Summary

Fish are a great source of many essential nutrients. Unfortunately, they are also a common source of exposure to intestinal parasites. Many people get infected with parasites from consuming fish, particularly raw or undercooked fish.

To avoid getting a parasite from fish, cook your fish thoroughly and avoid eating sushi or other foods with raw fish. To eliminate a parasitic infection, following a protocol involving antiparasitic herbs or medications is essential.

If you suspect that you may have a parasitic infection, consult with your doctor for testing and treatment.