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? It’s possible that the fish may have contracted an external or internal parasite during its journey. Wild-caught fish can be susceptible to multiple parasites. Unfortunately, most of the time aquarium fish don’t stay at the store long enough to make sure they are free of 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.
Hikari is well-known for their high-quality fish foods, but they also produce excellent fish medications under their Aquarium Solutions and Pond 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 has two active ingredients, formaldehyde & malachite-green chloride. It is safe for scaleless fish and invertebrates as well as live plants.
If your fish appears to have a lot of white salt crystals, it may be ich. 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. These are the steps to use Aquarium Solutions IchX
1. Perform a water change. Remove any chemical filtration (like activated carbon or Purigen) and UV sterilizers. 2. One teaspoon (5 ml), Ich-X for every 10 gallons water is recommended. 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 more powerful than Aquarium Solutions IchX. Follow the same directions, but use a dose of 1 teaspoon (5 ml), per 50 gallons. You can read the full article to learn more about how to treat ich.
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. wasting or skinny disease) – Gill and skin flakes (e.g. Gyrodactylus specie) – Hole-in the-head (HITH), disease (e.g. Spironucleus and Hexamita species)
ParaCleanse has praziquantel for worms and flukes. It also contains metronidazole for certain bacteria and protozoans. It is safe to use on scaleless fish, fish fry and shrimp as well as snails, shrimp, and aquarium plant species. 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 your aquarium and get rid all chemical filtration or UV sterilizers. 2. On Day 1, dose 1 packet of ParaCleanse per 10 gallons of water. 3. Dose 1 packet of ParaCleanse for every 10 gallons water on Day 3. 4. On Day 5, perform a 25% water change on the aquarium. 5. To give your fish the best chance of recovering and gaining weight, wait 2 weeks before you administer any other medication. 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] The majority of parasites can be eliminated by repeating the 5-day treatment once. If you really want to make sure your fish are clean, wait 2 more weeks and repeat Steps 1-4 for a third treatment.
Tapeworms eggs are not affected by most medications, so we have to wait until the new worms hatch and can be treated. After 2 weeks, we recommend that you do not redo them.
ParaCleanse can be applied to multiple fishes at once. It isn’t very harsh so it’s not necessary to do several treatments. However, it can be a little expensive on the wallet, so try putting your fish in a smaller quarantine tank so that there is less water volume to dose.
Should the fish be medicated with food or water? It can be difficult to manage medicated fish food. Fish that are feeling sick often don’t like eating much, or at all. Also, it can be hard to monitor how much medicated food each fish is getting, so some fish may be consuming too much medicine while others are consuming too little. If you are only treating one fish that is still eating well, then medicated food might be a viable option. If you are treating multiple animals, we recommend medications that dissolve in the water and treat the whole tank so that we can ensure every animal gets the right concentration.
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.
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.
PraziPro works in a similar way to ParaCleanse. It is safe for fish and invertebrates as well as plants and beneficial bacteria. PraziPro is used primarily to treat flatworms, tapeworms, flukes and turbellarians. Follow these 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. Allow the medication to sit for seven days. Then, repeat the process as many times as you like.
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. ParaCleanse is first treated for five days. Then, wait two weeks. We then do another 5-day ParaCleanse treatment, and then we wait a full month. The final step is the PraziPro 7-day treatment.
Pond Solutions CyroPro is specially formulated to treat external parasites like fish lice (e.g., Argulus species) and anchor worms (e.g., Lernaea species). Cyromazine is an active ingredient that prevents parasitic insects from molting their exoskeletons. Therefore, it is safe for fish, plants, and snails, but consider removing your shrimp, crayfish, and other crustaceans before treatment.
1. Do a water change on the aquarium or pond and remove any chemical filtration and UV sterilizers. 2. Give the CyroPro a good shake and 1 teaspoon (5 ml), per 50 gallons. 3. Repeat the treatment seven days a week for at least 21 days. (Restart the treatment regimen if you miss a treatment day.)
External parasites such as fish lice (seen in the photo above) and anchorworms can be seen to the naked eye. They are commonly found on pond fish, like goldfish or 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.
Fritz Expel-P is a fast-acting dewormer used to specifically treat parasites such as planaria, roundworms and nematodes (such as camallanus red worms), nodular worms, 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.
Fritz ParaCleanse recommends multiple treatments to ensure all eggs hatch. Follow the manufacturer’s instructions and recommended dosage:
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. Do a 25% water change after 24 hours. Make sure to vacuum the substrate using an aquarium siphon. This will remove paralyzed and irritated worms. 4. After 1 week, repeat the treatment to get rid of any new worms that hatched out. 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.