My Quarantine Process for New Aquarium Fish Updated February 2023

Aquarium Fish Quarantine

One of the biggest mistakes for beginner fish-keepers is to dump the new fish, water and all, into an already established tank. Pet store fish are usually stressed from their trip from the breeder to the store, causing their immune systems to weaken. They are further stressed from the the trip from the store to your house. Many fish fall sick and die within the first two weeks of their purchase. How do we prevent our new fish from dying? The answer: a Quarantine Tank (QT for short)!

Blog post recently updated February 2023

I can't believe it, it's been almost 10 years since writing this blog post about aquarium fish quarantine an aquarium fish disease. Looking through the article, I found many dead links and advice and recommendations that were outdated. Many of the medications I had recommended were no longer available. I spent many hours editing and finding new sources of fish medications. 
Please note that your first remedy for sick fish is tank maintenance: water changes, substrate vacuum, and filter maintenance. 
You will also notice that my blog now has ads and affiliate links. Please show your support and purchase a needed item for your aquarium from one of my links. It costs you nothing and pays a small percentage to me. Thank you!

Quick Links

Week 1 Quarantine Week 2 Quarantine Imported Fish
Fish Diseases and Treatments
Ich (White Spot Disease) Fin Rot
Hexamita/Hole-in-the-Head Disease Swim Bladder Disease
Fish Bloat
Fungal Diseases Nematodes
Tape Worms Flukes
Potassium Permanganate Treatment

Quarantine for Aquarium Fish Starts the Day Before Purchase

Before you visit the pet store to buy your fish, have a quarantine tank ready with already aged,  heated, and aerated water. 

Equipment for Fish Quarantine

  • 5 Gallon Sterilite Plastic Tote (Use 10 to 28 gallon glass tanks for more fish. 1" of fish per gallon.
  • Aquarium filter or
  • Sponge filter (plus airline tubing, and an air pump)
  • Heater
  • Measuring spoons (buy a set for fish only)
  • Fish Net

Water treatments:
  • Dechlorinator
  • Methylene blue

Plastic Instead of Glass Aquarium

From reading the fish forums, I learned that many fish-keepers complain that they have no space for a quarantine tank, or it seems that a QT is too expensive since it's used so rarely. Why use an expensive, large, fragile glass tank, when you can use a small plastic storage bin? I use a Sterilite plastic container from Target. 

5 galling plastic container from Target
Sterilite Plastic Container

It has a small footprint of approximately 15"x10"x11" and is 5 gallons if filled 75%. It's see-through, has a lid, and easy to pick up and move around, even if it's half-full!**

**If you purchase more than 3 small fish, or buy larger fish, consider buying a dedicated 10 to 29 gallon tank for quarantine. More fish require more water and more space. I used a 29 gallon tank to quarantine discus fish.

Aging Tap Water

Fill your 5 gallon plastic container with tapwater and place a 25 watt heater and an airstone, and let the tank run overnight. The following day your tap water will have been aged and made safe for new fish. Aging tap water eliminates CO2 from the water which can cause stress to your new fish. Imagine what it would be like to breath in carbonated water. Ouch! I also add some dechlorinator neutralize any chlorine and chloramines in the tap water. I use Seachem Prime dechlorinator because it also neutralizes ammonia. Seachem Prime can be used 5x dose to reduce the ammonia in your aquarium. If you are starting a new uncycled aquarium, Seachem Prime is essential!

Seachem Prime Dechlorinator

Drip Acclimatizing Aquarium Fish

Float the fish bag in the QT 1/tank for 20 minutes. Then place bag in a container that keeps it upright (I used a tall yoghurt container), and open the bag. If the bag is too full, pour a little out. 

Pour 1/4 cup of QT tank water in the bag. Wait 10 minutes, then pour another 1/4 cup. Repeat 2 more times. 

Drain most of the water from the fish bag. I prevent the fish from falling into the sink by "pinching" the bag above the fish so that only that water will fall into the sink. This video demonstrates how I drain the water from the bag. Some fish-keepers drain their water over a net so that the fish fall into the net. Use this method if you feel that you may accidentally dump your fish down the sink.

When your bag is 1/3 full, pour your fish into the QT tank. 

Quarantine Water Filtration

I have switched from using a sponge filter to a small in-tank filter. It is superior to the sponge filter for a couple of important reasons:

Filter for Small Aquariums

  1. The filter is more efficient than a sponge filter since it has a small but powerful pump.
  2. The interior of the sponge is hollowed out so that you can place your own bio-seeded media from your current tanks. You can change the water less frequently since the media contains good bacteria, which is the key to reducing the deadly ammonia from your tank. 
  3. The included spray bar, when placed just at the surface of the water, is an efficient aerator. If you look closely at the surface of the water, you will see the micro-bubbles that the spray bar produces. 
  4. It's very small, easily fitting into the 5 gallon plastic bucket
  5. Easy to install and clean.
  6. Inexpensive at under $20

Sponge Filters

If you use a sponge filter, remember to use a Check Valve to prevent any electrocution and floods should the water back up into the pump. Valves should be used in every air pump situation. I have used the popular Hydro 1 sponge filters but I find that the bases crack easily. If I purchased another sponge filter, I would try the Aquaneat Mini Sponge Filter because it has positive reviews is less than half the price.

Hydro I sponge filter

Use a heater

I use a small 25 watt aquarium heater for the 5 gallon QT tank. 78 degrees F is a good temperature for most tropical fish. Discus fish, bump up the temperature to 85 degrees F.

Use a 50 watt heater for a 10 gallon tank and a 100 watt heater for a 29 gallon tank. For 

check valve and air pump
Check valve and air pump 
Air valves prevents accidents.

sponge filter and air pump installed in 5 gallon plastic tub
QT tank with sponge filter and air pump. 

Week 1 of Quarantine: Methylene Blue

New fish should be quarantined for at least two weeks. I use Methylene blue for the first two days during first week, then just clear water changes every day.

Week 2:  Just Water Changes

If your fish are eating well and have no symptoms, perform only daily water changes in the 2nd week of quarantine. Change out 50% of the water every day using aged dechlorinated water. 

New fish will eat food readily once they have adjusted to their new environment. I do not use any drugs (other than Methylene Blue) or medicated food for most store-bought aquarium fish.

What is Methylene Blue?

Methylene Blue (MB for short) bath to help boost the fish's immune system as well as prevent bacterial, fungal, or parasitic outbreaks. MB is a chemical with many benefits for stressed and/or sick fish:
  1. It is gentle to fish and does not cause them any stress. 
  2. Increases oxygen absorption in fish. Fish that have been in high ammonia environments like their shipping bags often have damaged gills. Methylene Blue helps fish increases their ability to absorb oxygen from the water. 
  3. Both a bactericide and fungicide. It is often used by fish breeders to prevent fungus infection on eggs. 
  4. An anti-protazoan that kills a common parasite, ich (Ichthyophthirius multifiliis)
  5. Absorbed in the body to treat internal infections. Methylene blue is easily absorbed through the fish's gills and skin to help fight internal infections. It also assists the absorption of antibiotics when used used together in a bath. 
  6. No build-up of resistance. Since Methylene Blue is not a "drug", the pathogens do not build up a resistance to it.

How To Use Methylene Blue

Methylene Blue is a solid blue powder that is easily mixed with water to produce a blue solution. I buy a pre-mixed solution called Kordon's Methylene Blue. Since it stains everything a blue color permanently, I suggest you pour it into a measuring spoon over a stainless steel sink, or a plate so that you don't stain your countertops or sinks. Then directly pour into the QT and mix with the spoon. The water will become a very dark blue.

You can also place a kitchen garbage bag under your QT tank so that any blue drips won't stain your countertop. 

methylene blue fish medication

Use a dedicated spoon and a plate when using Methylene Blue since it stains everything.

Water Changes Are Important in the Quarantine Tank

Since MB kills nitrifying bacteria, use a non-seeded sponge or filter in your tank while using methylene blue. Use the sponge with bio seeded media from your current tank during the second week of QT. Examples of bio seeded media from your current tank: filter floss or ceramic media from your filter in the display tank.

Since the filtration is reduced to mechanical filtration only, water in the QT must be changed at least 50% a day. To reduce fish stress, you can change 25% of the water in the morning, and 25% in the evening, and redose 25% of the methylene blue each time.

Age The QT Tank Water

Use aged, heated, and dechlorinated water to change the water in your QT tank to avoid stressing your fish. As mentioned above, straight tap water contains CO2 which causes stress to fish. To age water, you need to let it sit overnight with an air bubbler and a heater. You can use a small clean 3 gallon bucket for this purpose.

Use A Water Pump to Drain The Tank

I use an inexpensive  pump purchased from Walmart and a length of 5/8" vinyl hose (can be purchased at Home Depot) to quickly pump out water directly into my kitchen sink or a large 5G bucket. I also found a 95 gallon/hour water pump that comes with a 3.3' hose on

Water Pump for Small Aquariums with hose

Using a pump to drain aquarium

Week 2 of Quarantine: Imported Fish

Using Medicated Fish Feed During Quarantine

If you are receiving imported aquarium fish from an importer that does not pre-treat their fish, I recommend using medicated fish feed during the 2nd week of quarantine. Imported fish often have worms and other parasites and treating them before introducing them to your healthy display tank can prevent major problems. Also, fish are less stressed with the food and I've had a 100% survival rate using medicated food in my experience.

During the 2nd week of quarantine, I use the following medicated fish foods for my imported fish:

1. Anti-Protazoan Flakes from

These flakes contain Metronidazole which kill protozoans like Hexamita. You can read more about Metronidazole further down this blog. Feed exclusively for 7 days 2x a day.

During the 3rd week of quarantine, and feed my fish deworming flake.

2. Deworm Flake 1 from

These flakes contain Fenbendazole which kills nematodes like camallanus. Feed every other day for a total of 5 feedings. You can use your normal fish flake on the odd days.  Feed only once a day at the end of the day to keep fish hungry. I use these flakes during week 3 of quarantine.

Fish Diseases and Treatments

Before starting any treatments, perform a major water change of 50%-75%. Use aged dechlorinated water that has been sitting overnight with an airstone stone aerater with an airpump.

Aging Tap Water

Fill your 5 gallon plastic container with tapwater and place a 25 watt heater and an airstone, and let the tank run overnight. The following day your tap water will have been aged and made safe for new fish. Aging tap water eliminates CO2 from the water which can cause stress to your new fish. Imagine what it would be like to breath in carbonated water. Ouch! I also add some dechlorinator neutralize any chlorine and chloramines in the tap water. I use Seachem Prime dechlorinator because it also neutralizes ammonia. Seachem Prime can be used 5x dose to reduce the ammonia in your aquarium. If you are starting a new uncycled aquarium, Seachem Prime is essential!

Skip Aging the Tap Water: Buy RO Water

If you want to skip the water aging process, buy 1 gallon or larger bottles of Reverse Osmosis water from the grocery or big box store. 

Purified water options from Target and Walmart

You can buy the 5 gallon water cooler jug and fill it at Walmart. Use a clean vinyl tube to siphon  the water to the QT tank.

Most fish bounce back after daily water changes in your display tank for a week. Remember to clean the substrate throughly using your aquarium vacuum hose to vacuum out wastes.

If your fish is not responding to water changes, place your sick fish in a quarantine tank. Water changes are more frequent in a quarantine tank.

Water Changes for Quarantine Tank

If you use a seeded sponge filter, change the water 50% every other day. A seeded sponge filter is one that has nitrifying bacteria. This is a sponge filter that has been running in an established aquarium for at least a month. 

If you use an internal filter with filter media from your current tank, like ceramic media, change the water 50% every 2 days. The media would be the type that is never replaced in your tank. 

If you use an unseeded filter, 50% water changes daily,  25% in the AM, 25% in the PM. 

During quarantine, your fish should be closely observed for strange behavior, and signs of disease. You can use store bought Drinking Water (Reverse Osmosis) for water changes for your QT tank. 

Ich (Display or QT Tank)

Ich is a protozoan parasite that often affects weakened fish. This disease is characterized by white raised round dots that cover the body of the fish.

Non-Drug Method Treating Ich

Ich can also be successfully treated with just high temperatures. I myself have not used this treatment, but others have had great success. Raise the temperature in the QT or the main tank to 87 degrees for two weeks with regular water changes and substrate vacuumed thoroughly to suck up any tomites (little white cysts) that have fallen off your fish. Some fish-keepers also add salt (ranges from 1-3 tbs./5 gallons) with every major water change. Use salt only if your fish can tolerate salt. Do not use salt if you have plecos and other scaleless fish or snails.

Seachem Paraguard (Display or QT Tanks)

Seachchem Paraguard is a gentle formula to treat ich and is a bactericide and fungicide. It does not affect the filter bacteria so it can be used in the display tank. Can be used instead of Methylene Blue for new fish quarantine tank. Treatment for ich is 14 days to ensure that the parasites are killed.  

Fin Rot

Fin rot is an indicator that your water quality is not ideal: ammonia and nitrites above 0, nitrates from 10 to 20 ppm. Fin rot can also be brought about by fin nipping. 

Clean Water Changes Only

Clean water is usually the easiest and safest way to cure fin rot. Start with 50% water changes daily in the main tank, with a substrate vacuum. Add salt at 1 tbs/10 gallons ONLY IF YOU DO NOT have snails and scaleless fish like cories and plecos. Replace 50% salt daily and continue for a week. 

Methylene Blue (QT Tank Only)

If your fish becomes worse after a few days  of water changes, quarantine your fish in separate tank filled with aged water with methylene blue, and a heater, an airstone, and a sponge filter. If you are using a 5G tank, you need to change your water out 50% a day, re-dosing 50% of the methylene blue. Continue this treatment for 2 days. Remember to use an airstone.

Acriflavin (Display or QT Tanks)

If methylene blue is not not healing your fish, Acriflavin is your next step. You can use in the same tank you were treating your fish with methylene blue. Just do a 50%-100% water change. Remember to use an airstone.

Acriflavin is commonly used to prevent and treat fungus infections on fish eggs. It is also used as an all-purpose antiseptic to treat bacterial, fungal, and even parasitic infections. API Fungus Cure contains Acriflavin in the ingredients. The dosage is (taken from the API website)  5 ml per 5 US Gallons (19 L) of aquarium water. Repeat dose after 48 hours. Wait another 48 hours then change 25% of the aquarium water and add back fresh activated carbon to your filter to clear the drugs from the water. For the QT tank, perform daily water changes and add back the treatment the percentage you took out.

While researching, I noticed that Fungus Cure is really hard to find. A well-known discus breeder, Jack Wattley, sells 100% acriflavin powder from his website. The dosage is 1 gram per 40 gallons. You will need a gram scale to measure the powder accurately. To create ready made solution that fits a 4oz  bottle (.1% solution), mix 0.125 grams of acriflavin powder to 4 oz of distilled water. 1 tsp treats 1 gallon  of water. 

My Calculations to mix the .1% solution

1 gram of chemical / 40 gallons of water = x grams of chemical / 1 gallon of water
x = (1 gram / 40 gallons) * (1 gallon / 1,000 ml) * 1 ml x = 0.025 grams
This means that we need 0.025 grams of the chemical in 1 ml of solution to treat 1 gallon of water.
To create a concentrated 4 oz solution where 1 tsp treats 1 gallon of water, we need to dilute the 1 ml solution further.
1 tsp = 5 ml (approximately)
1 oz = 29.57 ml 4 oz = 4 x 29.57 = 118.28 ml
Since we have a concentration of 0.025 grams of the chemical in 1 ml of solution, we can calculate the amount of chemical we need to add to 118.28 ml of water to make a concentrated 4 oz solution that treats 1 gallon of water per 1 tsp of solution as follows:
0.025 grams / 1 ml = x grams / 5 ml
x = 0.025 grams / 1 ml * 5 ml = 0.125 grams
This means we need to add 0.125 grams of the chemical to 118.28 ml of water to create a concentrated 4 oz solution where 1 tsp treats 1 gallon of water.

Primafix (Display or QT tank)

This is a controversial treatment. Many fish-keepers feel that Primafix and Melafix are the "snake oil" of the aquarium trade - chemicals that do not have any affect on your fish. I actually use Primafix when I see a signs of minor fin rot on my fish since I already change 75% of my water every other day. I first do a 75% water change in the main tank, then add the Primafix after I have refilled the tank. I repeat this for 5 to 7 days, with daily 75% water changes and re-dosing the Primafix. One could argue that the clean water cured the fin rot; however, after the Primafix treatment I notice that all the fish look more healthy and vibrant.

Hexamita and Hole-in-the-Head Disease

Hexamita infection is common in cichlid aquarium fish, especially discus. 

During the 1st week of quarantine,  I noticed that my discus fish were refusing food and spitting out their food. By the 2nd week, my fish were getting thinner with a hollow stomachs, and had clear or white stringy poop. These symptoms together is a good indicator that the my fish was infected by the flagellate parasite Hexamita. The infected fish usually has no appetite and will start to look skinny and pinched if not treated.

Hexamita is also attributed to Hole-in-the-Head disease, where the fish develop craters in their forehead.

Advanced fish-keepers will take a skin scraping sample and put it under a microscope to see what is affecting the fish. Here is a photo of the hexamita parasite:

photo of hexamita parasite

Using Metronidazole (Display or QT Tank)

To treat this disease, raise the temperature to 87 to 90 degrees F, and use Metronidazole, which can found at for a 10 day period, with daily 25% water changes and adding a full dose of Metro every time. When raising the temperature in the QT, add an airstone to increase O2 levels as warmer water holds less oxygen. Dosage is 1/2 tsp per 20 gallons.

Hole-in-the-Head disease is also treated using Metro but with the addition of high quality food that contains vitamins and minerals.

After treatment, more frequent and large volumes of water changes should be adopted to prevent the reoccurrence of Hole-in-the-Head.

**Metro can kill good bacteria in your tank. Test the ammonia and nitrite levels in your tank and use Seachem Prime to dechlorinate your water since it neutralizes ammonia in your tank.

Prevention of Hexamita using Epsom Salt in Feed

There are studies that indicate the use of epsom salt in fish feed prevents Hexamita from infecting fish.  The magnesium sulphate acts as a laxative and helps the fish purge the parasites from their gut. 
Mix 1 tablespoon of epsom salt with 500 mls of RO water. Soak dry chunky foods such as pellets and freeze dried blackworms for 15 minutes, then feed to your fish. In the near future, I plan to use feed my discus fish epsom soaked food once a week. 

Garlic to Treat Hexamita

Cichlid fish-keepers have long discussed the benefits of garlic. Recently, studies have shown the effectiveness of fresh garlic against bacteria and flagellates, such as Hexamita: It's not a conclusive study, but it shows that garlic has some effect on Spironucleus type flagellates. I use fresh garlic as a preventative and immune booster to my fish. I crush a fresh clove of garlic with a garlic press into a small bowl. I mix the contents with a little RO water and strain. Then I soak freeze dried black worm in the garlic juice then feed to my discus fish.

Swim Bladder Disease (QT Tank Only)

Fish affected by swim bladder disease have difficulty swimming upright. Remove the fish into a 5 gallon QT tank and treat with Methylene Blue and Kanamycin, a gram-positive antibiotic. Use a heater to keep the water 78 degrees F. Perform 50% daily water changes and redose 50% for 7 days. Continue with treatment for another 5 days if the fish still has problems righting itself.

Fish Bloat (Display or QT Tank)

Bloat is characterized by a swelling in the abdomen area caused by constipation. Place fish in 5 gallon QT with 1/4 tsp. of epsom salt with daily 50% water changes daily. Feed fish crushed cooked and shelled peas. If they refuse to eat the peas (my fish do not eat peas), you can also feed them small amounts of frozen brine shrimp. This procedure should loosen the intestinal blockage. You can also add epsom salt to your display tank 1 tbs per 40 gallons. Plants will love the magnesium sulphate.

Columnaris (QT Tank Only)

Non-Medicated Treatment for Columnaris (QT Tank Only)

Columnaris (flavobacterium columnare) is a highly contagious, fast-acting, gram-negative bacteria that causes white, or grey ulcers on the mouth and body. Sometimes these ulcers have a cotton look to them.

A non-medicated treatment for columnaris is my preferred method to treat columnaris. The infection spreads incredibly fast and needs to be stopped immediately by an oxidizing dip in potassium permanganate bath (please read the section below "Potassium Permanganate for Bacterial and Fungal infections").

If the lesions are small, place the fish in a clean QT tank and treat with acriflavin for 4 days. Do 50% water changes every day and re-dose 50%.

If you fish did not respond well to the either the PP or acriflavin bath, or the infection is serious, place the diseased fish in a clean QT tank and treat with antibiotics Methylene Blue, Kanamycin, and Bi-Furan , which is a combination of two antibiotics, Nitrofurazone, and Furazolidone. Lower the temperature in your tank to 75 degrees if your fish can manage that temperarature since the bacteria grows the fastest in 78 degrees F. Treat for 10 days with 50% water changes daily and redose.

Another antibiotic is Oxytetracyline treats both gram positive and gram negative bacterial infections and is effective treatment for columnaris. Dosage is 1/4 tsp for every 20 gallons. Treat every 24 hours for 10 days with daily water changes. Drug is ineffective in high PH environments. 

Finish the full course antibiotic treatments to prevent creating a "super-bug" that will defeat any antibiotic treatment. 

bifuran fish antibiotic

Fungus (Display or QT Tank

Jungle Fungus Clear

Fungus infections affect the fish's skin causing hair like growths that can grow into small hairy balls. Perform a 30% water change, and gravel vacuum, and use Jungle Fungus Clear. One table treats 10 gallons of water. Day 4, perform a 30% water change and retreat. Jungle Fungus Clear also treats dropsy, a very serious condition where the fish's scales puff out like a pinecone. 

Acriflavin (QT Tank Only)

Acriflavin is commonly used to prevent and treat fungus infections on fish eggs. It is also used as a all-purpose antiseptic to treat bacterial, fungal, and even parasitic infections. API Fungus Cure contains Acriflavin in the ingredients. The dosage is (taken from the API website)  5 ml per 5 US Gallons (19 L) of aquarium water. Repeat dose after 48 hours. Wait another 48 hours then change 25% of the aquarium water and add back fresh activated carbon. I recommend using a quarantine tank for this treatment. Potassium Permanganate baths also treat fungal infections. Please read below how to treat.

Nematodes (Red Worm Disease): Display Tank

Fish can be affected by a red nematode worm called the camallanus. Fish affected with camallanus have a red and swollen anal area; sometimes you will be able to see the red worm poking out of the anus (I know, gross!). I use a dewormer, Fritz Expel-P which contains the dewormer Lavamisole. Use in the main tank once a week, for 3 weeks, performing a 80% water change before every treatment. Dosage is
one packet per 10 gallons of aquarium water and add it to a high flow area. Treatment requires one dose, treatment period is 14 days. Lavamisole will not affect the bio filter. Mix with a bit of distilled water and pour into tank.

Tapeworms: Display Tank

When fish are eating and excreting well, but are growing slowly or looking thin, they could have tapeworms. I treated my discus fish for tapeworms during quarantine as a preventative as discus imported from Thailand often have worms. I used 100% pure Praziquantel powder, a white powder that does not dilute well in water. The treatment is 1/4 tsp or 250mg per 25 gallons. The package comes with a scoop to measure out the drug. 

Easy to use Praziquantel is the liquid Prazi-Pro, available at

Most store bought fish will not have tapeworms. Use this drug only if you see a white worm protruding out from your fish's anus.

Praziquantel Treatment

Perform a large water change and gravel vacuum before treatment. Using a measuring spoon, measure out 1/4 tsp. of Praziquantel to 25 gallons of tank water. Use the scoop supplied with the Prazi-Cure Package.

Mix powder in an empty water bottle with a couple of tablespoonful of vodka. Cap and shake well. Pour the resultant slurry (you will still see undissolved powder) into your tank where there is a high current (near the outlet of your filter). You can also use hot, but not boiling water instead of vodka. Perform a large water change after 24 hours. Repeat treatment one week later. Praziquantel will not affect the bio filter.

**Please note: I treated my fish recently with praziquantel and one died. I noticed he was acting stressed. He was very dark, lethargic, and sitting in a corner. But I since I had treated him with the same drug a few years ago, I didn't think much of it. In retrospect, I should have stopped treatment immediately. 

The moral of this story is to 👀  watch your fish carefully during any treatment.If they are acting very stressed, stop treatment immediately by performing a large water change and run carbon to soak up any remaining medication.

You will need an empty water bottle, (cheap) Vodka, and 100% Praziquantel powder.

Using a measuring spoon, measure out 1/4 tsp. of Praziquantel to 25 gallons of tank water.
Use the scoop supplied with the Prazi-Cure Package 

Use a funnel to pour Praziquantel powder and the Vodka into the empty bottle.


Praziquantel to Treat Flukes (Display Tank)

Praziquantel is widely used to treat fluke infections in aquarium fish. Symptoms are head shaking, choking movements, and flashing (rubbing gills on decor). The best approach is to get a positive ID before treatment by performing a gill scraping and put it under the microscope.

Easy to use Praziquantel is the liquid Prazi-Pro.  

Please note that the overuse of Praziquantel has developed stronger strains of flukes which are resistant to this drug.

Photo of flukes

Fluke Treatment for Small Aquarium Fish (Display Tank)

Perform a 50% water change, and clean gravel well with vacuum. Take out carbon from filter. Add Prazi-Pro to your tank at a high current area of the tank. Seven days later, perform 50% water change and redose 50%. Repeat cycle for 4 weeks. On the 30th day, perform a 50% water change and add new carbon to the filter. 

Fluke Treatment for Discus

Flukes are notoriously difficult to completely eradicate from an aquarium. The treatment must be done in a bare bottom tank. It's a 14 day treatment, with 50% water changes every other day, redosing the meds you took out (50%). On the 7th day, net your fish and put them in a bucket with aged heated water with an an stone. Wipe down the walls of the tank with a bleach solution (1 part bleach to 5 parts water), dump the water out of filter, and wipe down filter walls with bleach solution. Refill QT tank and dose 100% of the medication.

Display Tank Treatment Discus

Praziquantel treatment is often unsuccessful in a planted display tank since the flukes can hide in the substrate, plants and decorations. Sadly, to truly eradicate flukes the contents of the fish tank need to be thrown out, and the tank sprayed down with a bleach solution (1 part bleach to 5 parts water). Let the tank sit for 10 minutes, then rinse out thoroughly and let dry. Flukes are incredibly resistant to most cleaning chemicals except bleach. Flukes have even survived a potassium permanganate treatment.

To be completely safe, start a new fishless cycle in your tank with a new filter and new filter media.

Treating Flukes with Trichlorfon (Display Tank)

Trichlorfon is a strong insecticide that is used by gardeners to rid lawns of grubs. When I first bought my discus, I used Anti-Fluke Lifebearer liquid medication to treat for flukes. Sadly, this drug is no longer available. Mardel's Clout was the replacement and now this is also no longer in production. 

I found another fluke treatment for fish called AAP Aquatronics Dyacide

Dyacide Directions

"Fill Bottle to the neck with tap water (or better RO or DI water). Replace cap and shake very well.
Add ONE Drop per each NET gallon of aquarium water. Treat daily for 3 consecutive days.
Repeat treatment in 3 days if necessary or if parasites on fish reappear. Double dose for Marine Aquariums"

This is a maximum 3 day treatment. Any unused drug must be thrown away as it is unstable once mixed with water.  

Sensitive fish, like tetras, may not survive this treatment. Fish will lose their appetite and may be stressed during treatment. Do not use with invertebrates or scaleless fish and bottom feeders. 

If you want a display tank treatment, this would be my first choice. This chemical has a better chance of eradicating flukes from a planted tank or a tank with substrate. As with all medication treatment, perform a large water change and substrate vacuum before adding medication to your aquarium.

Treating Flukes with Flubendazole (Display Tank)

Flubendazole is a powerful medication that treats a variety of diseases, such as camallanus worms, hexamita, and flukes. The only place that sells this drug in the US is Inkmkr. He is a fish hobbyist who is kindly supplying hard to find medications to fellow aquarists.

The treatment dosage is 1/4 tsp. per 20 gallons. To dissolve flubendazole, use a two tablespoons of Vodka and mix in an empty bottle to form a slurry. Perform a large water change before adding the medication.

On day 3, perform another large water change, and redose. After 5 days, perform another large water change then run carbon in your tank to soak up any remaining medication. Two weeks later, repeat treatment and leave in tank for 3 days then perform a large water change and run carbon.

Some fish have an adverse reaction to flubendazole. Discus owners have reported that when dosing with flubendazole, they will have one fish in a group react poorly, with head standing and their body darkening.

If you wish to treat your fish in the display tank, this would be my second choice.

Potassium Permanganate Fish Treatment:
QT Tank Only

Potassium Permanganate (PP for short) is a purple crystalline mineral that is readily mixed with water. Potassium Permanganate is an oxidizer and kills bacteria, fungus, and parasites. Many fish-keepers use it as a bath to clean tanks, filters, nets, tubing, heaters, etc. I use a strong purple solution to soak all my quarantine gear for 24 hours.

1) Potassium Permanganate Sterilizes Fish Gear

Fill your QT with water and place all your QT gear in the tank. Pour a teaspoon of PP powder in the tank and mix with one of your nets. The color of the water should be a strong purple color. Check the color every couple of hours to see if the water has turned brown. If it has, either drain and start again or add another tablespoon of PP powder so that the color turns a strong purple again.
Potassium Permanganate Crystals

2) Potassium Permanganate Sterilizes Aquatic Plants

Potassium Permanganate is an excellent pre-treatment for new aquatic plants that are purchased online or from a fish tank from the pet store.  The PP will kill bacteria, fungus, and parasites but will not harm the plants. 

Rinse out the plants with tap water, cut away any dead or dying leaves. Place the plants in a container with enough water to cover them. 

Make a stock solution of Potassium Permanganate:

Mix 1 tbs of PP with 2 cups of RO or distilled water in a plastic bottle. I use a clean empty drinking water bottle. The color of the solution should be a very dark purple. If it's not dark purple, add another teaspoon of PP powder, cap and shake.

Pour a 1/4 tsp at a time of stock PP solution in your plant container until the water turns purple. Please refer to the photo below. It should be as dark as the 3rd beaker.  It should. Every 1/2 hour check to see if the solution remains purple. If the water is turning brown, pour another 1/4 tsp of stock PP into the water. Soak plants for 2 to 3 hours. 

2) Potassium Permanganate for Fish Bacterial and Fungal Infections

PP can also be used to treat bacterial and fungal disease in fish. Methylene blue is very gentle and may not cure stubborn surface bacterial and fungal infections in fish. When I purchased my black tetras, I noticed a week after I placed them in my main tank, that they were developing mouth sores. I quickly netted all 25 out and put them back into QT.

This time, I gave them a Potassium Permanganate bath. Using PP to treat infected fish is an advanced treatment method used by the most experienced fish-keepers because this treatment could be very deadly to fish if not done properly. Potassium Permanganate burns away all organics in the tank, including all bacteria, fungus, parasites, and the slime coat of fish. Thus, if you use too high a concentration, you could burn the gills of the fish and cause them great stress (and death).

Potassium Permanganate Treatment Method For Fish

Using a measuring spoon, and a funnel, pour 1 tablespoon of PP powder into an empty water bottle. Add about 2 cups of RO water into the bottle, cap and shake. The color of the solution should be a very dark purple. If it's not dark purple, add another teaspoon of PP powder, cap and shake.

potassium permanganate powder
Potassium Permanganate is a purple powder

potassium permanganate mixed with water
When mixed with water, the PP dissolves into a dark purple liquid

3 beakers filled with water and a bottle of PP solution

The only way to use PP is to "eyeball" the correct color the tank water should be. This is where experience comes into play. The catch is if you never try it, you will never gain the experience. To demonstrate the correct color, I set up 3 beakers of water and mixed up a strong solution of PP. Using a pipette, I slowly added drops of PP solution to each beaker. The first beaker is the color I aim for when treating - a light pink color.

potassium permanganate added to the beakers in 3 different concentrations
When mixed with water, the PP dissolves into a dark purple liquid. 
The 1st beaker is the color to treat fish.
The 2nd beaker is the color to treat plants.

Mixing Potassium Permanganate Solution

Add potassium permanganate solution a drop at a time to quarantine tank.

Add and mix until the tank is a pink color like above. 

The water in the QT tank needs to be aged 24 hours before. If this is an emergency treatment, use heated RO water purchased from your local store. 

The QT tank needs to stay this pink color for 4 hours. If the organics in the tank are too high, the water will turn a brown color. To maintain this pink color, you need to check the QT color every 1/2 hour, adding small amounts of PP solution if needed.

You will still need to keep the fish comfortable by aerating the water well, using an airstone, and a heater.

To demonstrate this color change, I placed a handful of moss from my shrimp tank into the first solution. There were a few shrimp babies stuck in the moss, and they were unharmed by the PP solution.
first beaker is filled with moss and PP solution
Moss was placed into the first beaker to add organics into the solution

After 10 minutes, I removed the moss, and the PP solution color was noticeably brown, although slightly pink. At this point, I would add a tiny amount of PP mix to increase the pink color. If the water turns brown or clear, the PP is no longer working and therefore, will not be an effective treatment. After the minimum 4 hour treatment, do a massive water change. If the fish have not improved enough, do another PP treatment after 2 days.

potassium permanganate turns brown when exhausted.
Potassium Permanganate solution turns a brown color with the presence of high organics

Accidental Overdose

If you accidentally added too much Potassium Permanganate mix to your tank, you can neutralize the Potassium Permanganate with a tablespoon or two of hydrogen peroxide, or a double strength dosage of Seachem Safe dechlorinator. The water will clear of pink almost immediately.

Fish Gloves

This is also a good thing to have around: fish gloves. They are long, reaching up to your shoulder, and are disposable. Great for cleaning tanks!

fish gloves from Fleetfarm

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