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Metro Discus Medication (metronidazole)

by | Mar 30, 2020 | 17 comments

Metro Discus Medication

Okay, we’re here today to talk about internal parasites. Internal parasites are usually caused by flagellates. We’re not going to get too intense into the marine biology as possible. After all, we’re here to treat your discus, we’re not here to give you a marine biology tour. I want to make it as simple as possible. This is not exactly one of the fun videos that I like doing, but it is what it is. Everybody’s asking me for it, and they want exact dosages to save your discus, and I completely understand. 

What’s Hexamita?

We’re going to refer to the Hexamita as internal parasites throughout the entire video, just to make it a general thing. If you want the details on Hexamita you can read about it at Wikipedia. So, why do fish get Hexamita, or internal parasites?

What Are You Feeding Your Discus?

Basically because their immune system weakens, just like we catch colds, it’s very common. A lot of the phone calls that I get, I always ask, and I know I’ve said it in the other videos, what are you feeding. 99% of the time it’s frozen bloodworms. Guys, I’m telling you, I’m not talking you down. You can feed all the bloodworms you want, but if you’re going to feed bloodworms, get into the habit of every three months deworming your fish. 

In This Video, I’m Going To Show You How To Deworm Your Discus.

Now, if your fish stop eating altogether, and they’re just thinning out, and you can usually tell. If a fish has internal parasites, the first thing you notice is the white poop, the white stringy poop, they leave it everywhere. 

The second thing you notice is that they stop eating and obviously start losing weight. When you start seeing that razor-thin forehead, where the eyes are popping out, and it looks like you basically took a piece of clay or dough and pinched it, and that’s what the forehead looks like, that’s your common sense denominator that should tell you, “Hey my discus have internal parasites.”

Now, if they’re not eating, alright? The idea is to treat the aquarium. Now, most people always call me and say, “Hey, Gabe, should I pull the fish out and put and put them on medication?

Yes, but remember the fish originally got sick in that tank which means the Hexamita’s in that tank. So, once you cure it and put it back, common sense will tell you he’s going get it again. So, my suggestion if there are other fish and only one is showing the symptoms, chances are it’s like a cold. Only one guy needs to show it, and then everybody else a week later has it. Take that into consideration. Please medicate the whole tank.

— Metro Product Page In Our Store —

What And How Do We Treat The Whole Thing?

Easy. We use one gram Metronidazole. Metronidazole, common name is Flagyl. We have now Metronidazole on our website along with other medications. I’m going tell you right now, we cannot ship these medications across borders. People in Canada, Metronidazole is illegal, so no, we cannot, all right? 

Last thing I want is to have long hair and shipping out white powder. All right, it sounds funny, but I don’t want the DEA over here. Internally within the United States, yes, we can, not a problem. We’re going to have a disclaimer on our website, it’s going to clearly state that you guys are using it strictly for your fish, okay, that’s the only way we can sell it to you.


Getting back to the treatment, we want to use one gram for every 20 gallons (75.71 l) of water. So, If you’ve got a 100 gallon (0.38 m³) tank, you’re going to need 5 grams. 

Here’s the thing about metronidazole that you guys have to understand. Once metronidazole comes in contact with water, it’s alive or active for eight hours exactly. 

Take that information and let it sink in, because I’m seeing a lot of guys making up three, four or five pounds of fish food and adding the metronidazole right in. Remember, if you’re going to feed right away, it’s going to work for you. But if you’re going to feed a week later or a month later with that frozen food, there’s no longer any more metronidazole in that water, because once it comes in contact with the moisture in the beef heart, it’s done for after eight hours, so don’t throw your money away.

How To Medicate Your Food

In this video, I’m going to show you how to medicate your food in so many ways that it’ll be active once you feed it to them. If you’re lucky enough, and your fish are still eating, that would be the best way to save on medication and also the most efficient way because if they’re ingesting the metronidazole, that’s when it’s most effective. 

For Those Which Are Not Eating

But getting back to the ones that are not eating. We need to boost the temperature between 86 and 88. Why? When you boost the temperature to 86 or 88 in the fish tank, what ends up happening is you speed up their metabolic rate. And by speeding up their metabolic rate, they’re absorbing more of the medication through their gill rakers because they’re breathing heavier.

It’s like going to the gym and working out to lose weight and you come home and raid the refrigerator. Why? Because your brain is firing signals through your stomach, and it’s bypassing the fat around the stomach area, and saying, “Dude, we need food.” We’re doing the same thing. 

Treatment Procedure

So, if you’re going to have to do it in your tank, my suggestion to you is do a full treatment. The most efficient way that we’ve been able to clean fish out is by adding it for 10 days straight. 

So, you have 100 gallon (0.38 m³) tank just for references. You’re going to add 5 grams, we’re going to start the treatment on for hearsay. You’re going to start the treatment on Monday.

Five grams, you dissolve it in a couple of water, right out of the tank, pour it right in. Second day, same exact treatment. 

Water Changes

Everybody always asks me the same thing, “What about water changes?” Guess what? If you know that the lifespan of metronidazole is eight hours, you can do your water changes whenever you want eight hours after you add the metronidazole. 

So, if you’re only going to plan to do your once a week water change, add your metronidazole early in the morning, and by the afternoon when you come home from work, you can do your water change without a problem, because realistically there’s no more metronidazole. 

Now We Have To Carry That Treatment Out For 10 days.

I know that I spoke in the other video about the fact that some people do it every eight hours, and some people do it for 10 days. I’ve seen better results with a 10-day treatment because, God forbid, on the fifth day if something comes to life, on the sixth day, it’s going to get whacked with metronidazole. So, you’re going to wipe everything out that’s in there, which is a good thing. 

Now remember, metronidazole will go only after Hexamita. It’s not going to destroy your biological, so I don’t need any text messages or emails or anything like that, it’s going to go specifically after flagellates, and that’s what we want to wipe out. 10 day treatment, that’s it. 

How to Mix The Treatment With Food

Now, if you’re fortunate enough that your fish are eating, then the rest of this tutorial is going to show you how to mix it with the food so that they ingest it. Ingesting it is 10 times [00:08:00] stronger than putting it in the water, and obviously you use a lot less, and it’s very, very simple to do.

Here Are Two Ways Of Doing It

I’m going to show you two ways of doing it. One will be into the beef heart, the other one will be into the dry food if you want to. And for the guys who refuse to give up feeding on frozen bloodworms, I’m going to show you how to coat those bloodworms as well, so every three months or so, you can give them a treatment, and keep them nice and clean.

Step-by-Step Procedure

  • Deworming Using Beef Heart

I’m going to go and those steps right now that you guys get an idea.

Here you can see a piece of beef heart that we make up the formula. Beef hearts, spinach, crow meal, multivitamins, it’s all here. Now, we’re going to medicate this food because we’re going to use it immediately. In other words, this will be for one feeding right now that we want to medicate our fish. 

What we do is we take the metronidazole powder, and we sprinkle it on top. You can see how I do it like this. Basically, what we’re doing is we’re folding it right into the beef heart.

Make sure that you get it in. You don’t have to go crazy, too much, whatever falls on the ground, pick it up, fold it right in. 

This basically now becomes a medicated food that you can give your fish. Now, this is provided that they are eating. 

Remember, if they’re not eating, you’re just wasting food and medicine. This is ready to go, and I’m going to show you in a couple of minutes. We’re going to walk over to our fish tank, and we’re going to give it to them. For them, this is going to be a preventative because my fish got dewormed at least once a week, but this will be to prove to you that they will eat it. 

Now, the other option is when you’re using pellet food. I’m going to take some of these wild pellets from Tropical. We’re going to put them in the cup. Whatever it is that you’re going to feed. You notice I always make a mess. Now, just so you see, I have some metronidazole powder in here.

Now you can use water, you can use anything you want. Vitamin water, which you can make up yourself. I’ll show you guys later on in another video how to do that. You can use garlic guard like the one I’ve got here, which refuses to open. You can use anything you want as far as the liquid. You can get aquarium water out of the tank and use it. 

What you’re going to do is you’re going to fold that in that liquid. You’re going to put it into the– Boy, this is hard. You’re going to put it right into the metronidazole powder and you’re going to mix it in.

The only thing we’re going to do now is we’re going to take that metronidazole liquid. I might as well use the knife I used to open up the bottle with to mix it. We’re going to mix it really well, and then we’re going to pour it right on top of the pellets, or the flake food, or whatever we’re going to feed. 

Remember, flake food, pellet food, it’s like bread, so it will absorb anything you put in there. 

You throw it in, and you leave it in there for a minute or two. That’s all you need to do. Once those pellets soak in the medication, then you walk right up to the tank and wash the little cup out, run it inside the tank, and your fish will eat it.

Now, all of this is if you’re going to be feeding them, like I said before, not if you’re going to be treating them. Two different ways of doing it. You could also do this every three months if you want to use it as a preventative. Do it for maybe two or three feedings, Friday, Saturday, Sunday, let’s say, and that’ll clean them out. 

Anything that starts to build up will immediately be eradicated by this. But do it fresh, because like I told you before, that eight-hour shelf life, if you make up your food, and you wait till next week to feed, whether it’s this or this, it will be useless because the metronidazole will be the deactivated.

  • Deworming Using Bloodworms

I’m going to get some bloodworms now, and I’m going to do it with the bloodworms as well. I’m going to thaw some out so you guys see how we do it. We just put them on a paper towel, and thaw them out, and then sprinkle the metronidozole on top, and you’ll see how it’s done. It’s the same exact principle. 

We thawed out the bloodworms. Now what we’re going to do is we’re going to put them on a paper towel. Let all that excess water, as you guys can see, drain. We’re going to take our metronidazole and basically fold it right in. Same principle. Mix it in there. You don’t have to get too crazy. Don’t put too much. Just sprinkle it on the top layer. That’s more than enough. Because metronidazole is very, very bitter, and if you put too much of it, there’s a chance they may not want to eat it.

Just so you know, that’s actually more than enough. We leave it there for let’s say maybe a minute or two so it coats the worms. Obviously, we wanted to coat the worms because as soon as you throw your bloodworms in, you know that the fish hit them immediately. They’re going to take them in with the medication, coating them. 

That’s also a good way, like I told you before, every three months of deworming your fish, and making sure that these bloodworms aren’t causing too much damage. 

I brought this package in just to be able to show you guys how to do it with the bloodworms because we don’t use the bloodworms here at the hatchery at all. I stay away from them. We feed primarily the pellet food and the beef heart, and that’s it.

Once in a while on the breeding pairs, we give them California black worms as a treat just to stimulate spawning and all that, but that’s about it. 

Feeding In the Hatchery

Now, I’m going to take you through the hatchery and I’m going to show you how I feed. Now, some of the fish that are here obviously are not sick. They’re going to eat the food anyway. 

Basically, just for showing purposes, that’s why we’re going to do the rest of the video so you guys see how they do eat it. So follow me on the little journey of feeding. 

Here’s the tank with some of our wilds, and we have the pellet food, which we coated with their garlic guard and the metronidazole. You can see how these guys are already active with it. Basically, what you do is you take your cup and you wash it out inside. And that’s it.

Now they’re eating it. They’re ingesting that food, which contains the metronidazole. Now obviously if they don’t eat, like I said before, then you have to treat the entire tank, so they can absorb it through their gill rakers, through their body. 

Everything like that. Now we’re going to take the beef heart, and we’re going to walk over to the tank. This is the medicated beef heart going in. 

You can see these guys are not emaciated or anything, but basically that’s a good way of doing the three-month treatment to make sure that you eradicate any internal parasites whatsoever. 

We’re hoping that this video helps you guys out. We realized that we haven’t been around much on the YouTube scene, but it’s been crazy around here, and we want to thank all our customers for making it that way.

Appreciating All The New Zoos For Purchasing Discus From Us

All the new zoos that are now purchasing discus from us. Every one of them. I really appreciate their business. It is overwhelming at times, but I’m grateful, because after all, that’s where we work hard for. 

We’ll try, by all means, to bring you guys plenty of more information to help you guys enjoy these beautiful, magnificent fish. 

Take care, guys. See you soon. Don’t forget to check us out on Facebook, Instagram, and all the other feeds. 

We’ll be back real soon. You guys take care and enjoy the hobby.


author avatar
Wattley Discus Admin


  1. Mr. Terry L Evans

    Thanks for the information!

    However, you neglected to give dosage amounts when mixing with food.

    Still one gram per 20 gallons of tank water? Or since it is being ingested would it be less?

    Thanks again!

  2. Kevin Whirtener

    Is it still three days when feeding medicated blood worms? I appreciate the education. Thanks

  3. Kim Roy

    If treating the tank, is it necessary to turn off UV light or remove charcoal from canisters?

    • Wattley Discus Admin

      Normally you don’t need charcoal in your filter. We don’t use any.
      UV light is not a problem.

      • Abbas

        Gabe I have a 38.1 gallon tank and 6 discuss in it. On has the disease so can I but two grams of metronidazole 200 mg in it . Or is there a problem in doing that. Pls help Gabe

        • Gabe Posada

          Abbas its 2 grams per day per 10 days.





  5. Azmi

    Hi can i syrige directly from the mouth after mixing the metronizadole with garlic guard?

    • Wattley Discus Admin

      Very difficult but can be done with an soft tubing extension on your syringe and get meds right into stomach rather than out the gill plates.

  6. Ahmed

    Thanks alot for your advice, my question is can I use flagyl that used for humans to treat my discuss?
    Thank you.

  7. Alex Nguyen

    I received my 100g order and started treatment yesterday (1 of 10) The fish not eating, some still make white string feces. What symptoms am I looking for during the treatment period? How do I know if it’s getting better or worse, beside starting eating? I’ve a planted tank and I leave my UV light on, is it okay?

    • Wattley Discus Admin

      UV is ok Carbon filter is not if you have one.
      Eating is the best indication of healing. Look for normal habits not hiding or emaciation.

      • Steve Harley

        Dear Gabe, I have obtained a packet of Metronidazole from JWD (thanks for making it so easy to purchase it). I have a 100 gal tank, so the dose needed is 5gm. My problem is that I do not have a small pharmaceutical scale to measure out 5gm. Can you tell me a common measure by volume of 5gm. For instance is it about 1 teaspoonful, or what? Thanks, Steve Harley

  8. Tri

    Do I need to remove the activated carbon from the filter when treating the tank?


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