How to Treat Parasites In Aquarium Fish

How to Treat Parasites in Aquarium Fish

When you buy an aquarium fish, did you know that it has traveled from a fish farm to a wholesaler to a pet store before it got to you? This means that your fish could have acquired an internal or external parasite. Wild-caught fish are especially prone to carrying parasites, if not multiple types at the same time. Aquarium fish are often not kept in the store for long enough to check for parasitic diseases. If your fish has visible parasites on its body, a swollen abdomen, skinny disease, hole-in-the-head, or strange-looking, discolored poop, you may need to treat it with one of the following antiparasitic medications.


1. Ich-X

Hikari are well-known for making high-quality fish meals. However, they also produce great fish medications under the Pond Solutions and Aquarium Solutions product lines. After testing dozens ich medicines in the United States we found Ich-X to be the most effective for treating ich, white spot disease, other external protozoan parasites, and mild fungal infections. Ich-X is used to treat all fish entering our fish shop before they are sold to customers. It contains formaldehyde as well as malachite blue chloride. It is safe to use on scaleless fish, invertebrates and live plants.

If you notice that your fish is covered in tiny, white salt grains, it might be ich. It should be treated immediately. That’s why it’s good to always have first aid medications like Ich-X on hand.

There are two types: Aquarium Solutions IchX for small aquariums, and Pond Solutions IchX for larger tanks with 50 gallons and more. To use Aquarium Solutions Ich-X, follow these steps:

1. Do a water change and clean the aquarium. Take out any chemicals (such as activated carbon and Purigen) or UV sterilizers. 2. For every 10 gallons of aquarium water, add 1 teaspoon (5ml) of IchX. 3. Every 24 hours, change one-third of the tank water and repeat the dose. 4. Keep your treatment going for at least three more days after you have seen any symptoms of the disease.

Pond Solutions IchX is stronger than Aquarium Solutions IchX. Therefore, follow the same instructions but use a dosing ratio of 1 teaspoon (5 ml of medicine) per 50 gallons. For more details on how to recognize and treat ich, read our full article here.

2. ParaCleanse

Fritz ParaCleanse is another well-tested medication that we use to preventatively treat all new fish that enter our retail store, and it can be safely used in conjunction with Ich-X. It is used to cure internal parasites and some external parasites, such as:

– Tapeworms (e.g., skinny or wasting disease) – Gill and skin flukes (e.g., Gyrodactylus species) – Hole-in-the-head (HITH) disease (e.g., Hexamita and Spironucleus species)

ParaCleanse has praziquantel for worms and flukes. It also contains metronidazole for certain bacteria and protozoans. It is safe for fish, fish fry (scaleless), shrimp, snails, and aquarium plants. Follow the manufacturer’s recommendations if your fish is suspected to have one of these parasites. Don’t give the medicine half-doses as it may not be effective.

1. Clean the aquarium and remove any chemical filtration and UV sterilizers. 2. Dose 1 ParaCleanse packet per 10 gallons water on Day 1. 3. Dose 1 packet of ParaCleanse for every 10 gallons water on Day 3. 4. Perform a 25% water change at the aquarium on Day 5. 5. You should wait for your fish to gain weight and recover before giving them any other medications. Feed your fish foods rich in fiber and roughage to help them get rid of dead worms. 6. After 2 weeks, repeat the 5-day treatment by following Steps 1-4. (The medicine doesn’t affect eggs, so we need to wait for the new larvae to hatch. This is why it takes stores 2 weeks to get rid of all internal parasites. 7. [Optional] Repeating the 5-day treatment two times will eliminate the majority of parasites. You can make sure that your fish are healthy by waiting 2 weeks before repeating Steps 1 through 4.

Tapeworms eggs do not react to most medications. We must wait until the new larvae hatch so that we can treat them. After 2 weeks, we recommend that you do not redo them.

ParaCleanse is not very harsh, so multiple treatments are generally safe for your fish. ParaCleanse can be costly so you might consider putting your fish into a smaller quarantine to reduce the amount of water required.

Do you medicate fish’s water or fish’s food? This is a tricky question. Fish that are feeling sick often don’t like eating much, or at all. It can also be difficult to keep track of how much medication each fish is taking. This could lead to fish consuming too many medications while others are eating too little. Meditated food may be an option if you only have one fish that is eating well. For multiple animals we recommend medication that dissolves in the water. We can then treat each animal with the same medication.

This treatment plan works with the three-part quarantine med trio. Once you have successfully treated your new fish with a seven-day soak using ParaCleanse or Ich-X and Maracyn then proceed to Step 5.

3. PraziPro

PraziPro has a higher concentration of praziquantel, so we recommend using it when ParaCleanse isn’t quite strong enough or if we’re seeing a problem with certain shrimp parasites like Vorticella and Scutalleria japonica.

Similar to ParaCleanse, PraziPro is safe for fish, invertebrates, plants, and beneficial bacteria, and it’s primarily used to treat tapeworms, flukes, flatworms, and turbellarians. These are the steps to use PraziPro:

1. Clean the aquarium and remove any chemical filtration and UV sterilizers. 2. Shake the bottle well and dose 1 teaspoon (5 ml) of PraziPro per 20 gallons of water. 3. Let the medication sit for 7 days. You can repeat the dosage as often as you need, but not more than three times per day.

Wild-caught fish often contain lots of parasites that may require three rounds of treatment to fully deworm.

In our personal tanks, we’ve use PraziPro as part of the deworming process for our puffers. We first treat ParaCleanse 5 days, then wait 2 weeks. Then we do a second 5-day treatment of ParaCleanse and then wait a month. As our final deworming step, we apply the PraziPro 7 day treatment.

4. CyroPro

Pond Solutions CyroPro was specifically formulated to deal with external parasites like anchor worms and fish lice (e.g. Argulus) Cyromazine is an active ingredient that prevents parasitic insects from molting their exoskeletons. It is safe for plants and fish. However, you should consider removing any shrimp, crayfish or other crustaceans prior to treatment.

1. Do a water change on the aquarium or pond and remove any chemical filtration and UV sterilizers. 2. You should shake the bottle and add 1 teaspoon (5ml) CyroPro to 50 gallons water. 3. For at least 21 consecutive days, change the water and continue the treatment every 7-days. If you miss a day of treatment, you can restart the treatment.

External parasites, such as fish lice (seen below) and anchorworms, are easily visible to the naked eyes and can often be found on pond fish such as goldfish and Koi.

The water changes that occur before CyroPro are used to restore dissolved oxygen, remove excess nutrients, and decrease the population of water-borne parasites.

5. Expel-P

Fritz Expel-P, a fast-acting, dewormer, is used to treat parasites like roundworms, planaria, nodular and hookworms. Infected fish may exhibit signs such as anemia, a swollen stomach, red worms leaking into the anus, rapid breathing, or loss of appetite.

The active ingredient is levamisole hydrochloride (HCl), which causes paralysis and death of the worms, but it will not harm your biological filtration, aquarium plants, invertebrates, or healthy fish.

Like Fritz ParaCleanse, multiple treatments are recommended to ensure that all the eggs have hatched and can be affected by the medication. Follow the manufacturer’s recommendations and dosage guidelines:

1. Clean your aquarium and get rid all chemical filtration or UV sterilizers. 2. Dose 1 packet of Expel-P per 10 gallons of water. 3. After 24 hours, do a 25% water change, making sure to vacuum the substrate with an aquarium siphon to remove any paralyzed worms. 4. You can repeat the treatment once more worms have hatched after one week. 5. Continue the weekly treatments as needed until the worms have disappeared or the fish are regaining weight again.

Bonus: Aquarium Salt

If you do not have access to these medications, aquarium salt is useful for the treatment of external parasites (but isn’t as effective for internal parasites). The salt works by dehydrating the parasites to death before the fish (which have more mass and stored water) are affected. For complete instructions, see our full article on how to treat sick fish with salt.