How to Get Rid of Parasites in Fish Tank? – 3 Effective Ways

how to get rid of parasites in fish tank

No aquarist wants to see their fish get sick, making the question of how to get rid of parasites in fish tank units a valid concern. As aquarium hobbyists, we feel sad when we see our fish not eating, moving sluggishly, or showing signs and symptoms of parasitism.

Veterinarians can help you determine the parasite infecting your fish. However, you can also observe some measures to get rid of little white worms and other harmful organisms in the fish tank.

Keep reading to learn how to remove parasites from the aquarium and out of your fish’s life.

Types of Parasites in Fish Tank


Choosing the correct fish medicine for parasites requires understanding the two major fish parasite categories: ectoparasites and endoparasites.

Ectoparasites live on the fish’s body surface, including the fins, skin, scales, mouth, and gills. Examples are Trichodina nobilis, Oodinium, Gyrodactylus, and Dactylogyrus.

Meanwhile, endoparasites live in fish body organs, blood, gastrointestinal tract, and other tissues. Examples of fish endoparasites are trematodes (flukes), cestodes (tapeworms), and nematodes (roundworms).

Treating internal parasites in fish is a must because they can damage internal organs and cause death.

Here is a list of some of the most common parasites in fish tanks.

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  • Ichthyophthirius or Ich – causes “white spot disease,” appetite loss, abnormal hiding, and incessant rubbing against objects
  • Fish lice – very tricky to spot because they camouflage themselves
  • Anchor worms – can be challenging to remove, often causes bleeding on fish
  • Leeches – blood-sucking parasites
  • Flukes – affect the skin or gills
  • Piscinoodinium – causes “gold lust disease”
  • Hexamita – causes lesions on fish head and white stringy feces


What Causes Parasites in Fish Tanks?


Aquarium fish parasites do not enter the fish tank by themselves. The most common method of parasitic infestation in aquariums is the introduction of new fish (especially wild-caught) into the aquarium without undergoing quarantine.

It is the most natural way to cause parasitic infections in fish.

Most fish parasites are microscopic and live inside the fish or other organisms that fish eat (i.e., small snails and shrimp). When fish eat these organisms, they also ingest the parasites.

Introducing new fish to the aquarium can spread parasites to the original fish tank “inhabitants.” Quarantining new fish for up to six weeks can help prevent such a spread.

If the new fish do not get sick within the quarantine period, you can safely introduce them to the aquarium. If they become ill, you can give them parasite treatment and consider adding the fish to the stock after full recovery.

Ways to Get Rid of Parasites in Fish Tank

What to prepare: Treating fish parasitism requires fish parasite medicine. You can ask your veterinarian about the most appropriate medication.

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Method 1: Eliminate detritus worms.

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You might have seen leech- or earthworm-like tiny brown worms in fish tank units, especially on aquarium substrate (i.e., pebbles and sand).

These parasites are not harmful to fish. On the contrary, detritus worms maintain fish tank cleanliness and ensure a healthy and well-balanced aquaponics ecosystem.

Sadly, they can multiply and reduce oxygen and nutrient levels. Hence, it will be wise to remove these worms.

For this method, you need a gravel siphon, sponges, and two buckets.

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  • First, unplug the fish tank filter.
  • Fill one bucket with fresh replacement water, and leave the other empty. The empty bucket will hold the dirt, debris, and worms you siphon from the fish tank.


The setup requires you to draw worm-filled water from the tank and empty it into the bucket. Replacement water enters the fish tank from the other bucket once you remove 10 to 15 percent of the water.

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  • “Vacuum” the fish tank’s bottom and sides. Often, the siphon will have a button for you to press to activate it. Squeezing or shaking the device may also work.
  • Slowly refill the fish tank with the replacement water and test it for water quality, including pH.
  • Perform this technique weekly for several weeks.



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Method 2: Remove Ich parasites.

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Ichthyophthirius or “Ich” is a rampant freshwater fish parasite. Quarantining fish is necessary to prevent the parasite from spreading and infecting other aquarium inhabitants.

For this technique, you can use an anti-parasite product formulated specifically for Ich. A good example is PetCo’s Imagitarium Parasite Remedy, which is also effective against other fish parasites.

Ich formulations have different procedures. For example, Ich-X requires aquarists to clean the fish tank before treating it with the anti-parasite.

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  • Aquarium hobbyists must also remove UV sterilizers and chemical filtration devices.
  • Follow the recommended dosage, which is a teaspoon of anti-Ich medicine for every 10 gallons of aquarium water. For instance, you can treat a 40-gallon fish tank with four teaspoons of the formula.
  • Repeat the treatment every day for three days or more. Every time, change a third of the water and avoid pairing the product with other medication.



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Method 3: Get rid of other parasites with Praziquantel.

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An anti-Ich medication might be insufficient if you see symptoms of internal parasites in fish.

In this case, a more appropriate solution is Praziquantel. This medicine can fight hole-in-the-head disease, skinny disease, and skin-and-gill fluke infections.

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  • The first step requires aquarists to clean the fish tank and keep all UV sterilizers and chemical filtration systems away.
  • Read the Praziquantel manufacturer’s dosing instructions. For instance, ParaCleanse requires a packet for every 10 gallons of aquarium water (i.e., four packets for a 40-gallon fish tank). This dose is for the first day.
  • Repeat the dosing regimen on Day 3 (resting on Days 2 and 4).
  • Replace a quarter (25%) of the fish tank water on the fifth day.
  • Help the fish recover by feeding them high-roughage and high-fiber food (i.e., spirulina, daphnia, brine shrimp, and algae wafers) during the next two weeks. This diet helps the fish pass dead parasites from the intestinal tract.
  • Repeat Steps 2 to 4 (dose on Days 1 and 3 and water change on Day 5).


You can perform a third treatment cycle (five days treatment + two weeks recovery) to ensure parasite-free fish tank inhabitants.


Frequently Asked Questions


How do you know if you have parasites in your fish tank?

Observing your fish for any unusual behavior and physical changes should give clues about the possibility of having a parasite in aquarium units.

For example, frequent rubbing of the fish’s body against an aquarium object can indicate anchor worm infection. You might also notice inflamed body parts or whitish-green threads extending from the fish’s skin.

Other signs include oversecretion of mucus on the fish’s body, unusually fast gill movements, reddish skin, deformed fins, listlessness, protruding scales, bloating, salt-like spots, and frequent gasping for air at the water surface.

What temperature kills parasites in fish tank?

Ninety (90) degrees Fahrenheit is enough to kill parasites in fish tank units, especially Ichthyophthirius multifiliis or “Ich.”

Elevating the water temperature to this level for several days should eliminate these parasites without harming fish as they adapt to the temperature change.

What eats parasites in aquarium?

Yunnanilus cruciatus (hovering Zebra loach), Rhinogobius rubramaculatus (red-spotted Goby), and Macrobrachium peguense (boxer shrimp) can eat and kill worms in fish tank units, especially Planaria (flatworm).

Other species that can get rid of worms in fish tank units include Botia, Macropodus opercularis (Paradise fish), Betta splendens (Siamese fighting fish or Betta), and Anentome helena (hornet snail or assassin snail).

What is the average lifespan of parasites in a fish tank?

Freshwater aquarium parasites have a highly variable lifespan, ranging from three days to five weeks. The life cycle variability depends on water temperature (50 degrees for five weeks and 70 degrees Fahrenheit for four days).

It is also worth noting that parasites can have direct (fish-to-fish) and indirect (involving at least two hosts) life cycles. They can also have a free-living and parasitic phase, impacting the parasite’s lifespan.


How to get rid of parasites in fish tank units is an issue not to be taken lightly by a newbie or seasoned aquarist. Although the methods we shared in this article are straightforward, parasitic infections deserve a more professional approach.

Veterinarians can diagnose the correct parasitic infection affecting your fish and wreaking havoc in the tank. Only with a conclusive diagnosis can vets determine the best possible treatment plan.

It seems more prudent, on our end, to prevent parasitic infections by quarantining all new fish species for several weeks before adding them to the aquarium.