Posted by Son Nguyen on

Mastering the method of isolating newly imported discus will save time and money. The risk of disease transmission from these fish to other fish is very danger. There are many methods that you can use and below is one of them. Once you understand and master the method, you can tailor it to your conditions.

Before how, we should know WHAT to quarantine: Anything that you add to your discus tank and you couldn’t disinfect  ( with chemical or heat … ) should be quarantined, you buy air stone, heater,  drift wood, plants, sponge filter, bio media, canister  filter, Snail, gravel….you name it. ….if you are not sure it’s completely germ free or disinfected you should Quarantine. Last but not least let’s not forget new FISH! Or your own fish coming back from the show or coming back from your friend’s house,

There are two types of quarantines

  • Observation only QT,
  • QT + medications

For some of the above mentioned things its ridiculous to put into QT tank and observe, imagine you bought some used gravel or a piece of drift wood….here what I do I try to clean and disinfect as much as possible then try to rinse off completely then put it QT tank (specification will follow) and add a hero fish then observe, how about that! ….. For hero fish you should use one that is already in your community tank (not a new fish) and you are sure he is healthy. Almost all of us keeping a stunt discus that we love and we hate if he is healthy and eating use that one.


QT  TANK: use a bare glass tank (it’s easier to clean ) painted light color from outside all around except the front make sure you have a cover lid… for it QT is stressful process for fish I saw so many fish jump out over the night.  If you have some plastic plants or breeding cone or something to give fish a little bit sense of security put it in QT tank, use the smallest size tank (not less than 20 g) its saves you money if you need to use medication, you need a heater to set the temperature initially at 84. You need air supply, thermometer and you need sponge filter accommodating twice the capacity of QT tank so if you use 20g tank use the sponge filter that accommodates 40 g tank. The sponge filter doesn’t have to be seeded (cycled) as you will frequently change the water and using medication with kill beneficial bacteria in filter anyway but if you choose the observation QT you can use a cycled sponge filter some say it’s better I say it should be: fishless cycled (not been used in another tank with fish in it) for how to make fishless cycled filter search Dr. Tim’s fishless cycling.  Do not use a very bright lighting for this tank during QT. you need a separate fish net, syphon…if you can, setup your QT tank in separate room.


We only use 100% new water for shipping fish. We also add some medication to block ammonia spike and reduce fish stress during shipping.

a. We always Check all bags to make sure no back is leaking busted during transport and separate it out. If you see any busted bag, dump all water and fish from this bag to a clean bucket, add an air stone and start drip acclimate.

b. Floating bag into your aquarium for matching temperature. If your water parameter is too much different with our water, then please drip acclimate otherwise you just need to do flop and drop technique.

Flop and drop technique: 

I prepare a small bucket of methylene blue ( 1 ml MB 1% per 10 gallon ) as soon as you open the bag the pressure in bag changes and you will have ammonia spike so empty  the fish into a fish net and deep that fish in the MB bucket for 5 seconds ( this will inactivate the ammonia  spike and prevents some gill burns and fin burns….) then release your new fish in QT tank, turn off or better to dim the lights so you can observe your new fish, look for any abnormalities, sores,  white patches ….. Hold on! No feeding yet until next day I know it’s hard to resist you like to see them eating.

Drip Acclimate: 

Dump all fish and water from the shipping bag to a clean bucket, add an air stone and use an air tubing for drip acclimate until water is full and overflow out of the bucket. If you are not in the area that able to let water overflow then please dump some water out then let water fill up again. This step ensure fish will adapt to your water parameter well.


a) Net fish from the bucket to your QT tank. Remember that you should not release fish from busted bags with the rest because these fish skin may get trauma and this leading to infection.

c) Discard excess water in the bucket. Do not pour this water into the tank. The reason is that because fish are transported in bags for a long time, the amount of ammonia increases and bacteria arise. Furthermore, chemicals such as anesthetics or antibiotics in the shipping water remain active. And if we pour all or part of this water into the tank, it can affect or prevent treatment causing fish poisoning or death.


Observation QT:

We like to over kill it so the total duration is 6 weeks first 4 weeks its only watching them and cleaning and water changing and feeding and cleaning and water changing and cleaning did I mention water changing?! You should do water change as much as you can let’s say 80% first couple days. I like 100% everyday for the first week. Use your common sense and water parameters to keep the ammonia at zero ppm last two weeks you add your hero fish continue observing for any type of stress or cross contamination…. And hopefully that’s it

QT + Medications (Only using this way if fish arrival with sick condition)

Totally different methods depending on who is doing it, the water change part is the same as Observation QT but when you change water you re dose the medication part that is missing.

Here is mine (details not included as it will be long story): I give the fish two days rest on arrival then I do Epsom salt bath. Then for next 5 days I treat them with general cure during these five days temperature is around 90 F. Another two days’ rest, then every other day for 1 week I start using the mixture of malachite green and formaldehyde (I believe there is premade combination too) during this week the temperature is not more than 84 f. Give them few days rest then I do quick PP bath that’s the end of medication, but you keep the fish in QT for adding your hero fish for two more weeks.

*****Observation QT is easier, safer but longer

*****QT + medications is harder to perform, it’s more efficient, it’s shorter and it’s the only way if you noticed you received low quality sick fish. Or if your Observation QT fails.

Here is one important point about QT + medications: if you receive a sick fish for example with clear external bacterial infection issue, you address this matter first then you start your QT.

(Logic of using the each meds: Epsom salt for purging the fish from any parasite or worm Epsom salt helps other meds work better too, general cure for internal parasites and worms and gill flukes, malachite green and formaldehyde is for external parasites and continuation of gill flukes treatment (remember for gill flukes you need to treat for 14 days at least as these has dormant life cycle)…. PP external parasite, bacteria …. )

If you have been quarantining your fish for years using your own common sense and method and you have been successful always follow your own method and share it with us and we will appreciate it.


Salt and antibiotics

a) Add salt to the QT tank. Discus and most other aquarium fish tolerate salty water up to 2 ppt. In fact, many freshwater aquarium fish such as goldfish, loach, and can tolerate salty water up to 6 ppt.

Add salt to reduce osmotic pressure from external damage. Another benefit of adding salt is to treat skin parasites. Parasites that are localized below the scales are more difficult to treat and require long-term treatment with appropriate chemicals.

b) Quarantine fish is long process to ensure they are healthy before moving them to your main display tank so it is at least 3 weeks. In some case you may have to soak antibiotics continuously for 12 days. Never under-dose! If water changes are required, add medication after the change. The reason for antibiotic immersion is because we are not sure if one fish or the whole tank is infected with bacteria or not, but during the process, the possibility of infection is very high. In fact, the treatment of diseased fish is expensive and not always successful. It should be known that newly imported fish come from many sources and are out of control, so prevention is the way to avoid disease. Keep an eye on new fishes and treat the problem as need.

Remember turn off aquarium light the first 24 hours

Prevention is better than cure, and treating discus is a nightmare!

The only risk with using antibiotics is the risk of getting the wrong dose and creating a strain of resistant bacteria. To use antibiotics safely, we need to know: when, how much and how to use them. Resistance strains arise because we use the wrong antibiotics, the wrong drugs and the wrong fish/water/antibiotic control.


Start feeding the fish on the third day (counting from the day the fish came). Feed as little as possible even though they are very hungry. Do not over feeding at this time.

Remember, fish are usually starved for a day before shipping, but some peoples stop feeding the fish for several days. They think "no food, less ammonia, less bacteria so less fish die". But this does not keep the fish healthy.

Being starved for more than two days before shipping causes stress on fish. So, if you suddenly overfeed your fish, they can get bloated and get sick easily. Feeding once per day is sufficient for few days of isolation then increase later. Whenever the water becomes dirty or cloudy, the water must be change.


Infomation under this post is base on our experience and coppy right from KIA.

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