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How to medicate your fish correctly

by | May 1, 2023 | 2 comments

How to medicate your fish correctly

“Welcome back. A little touch-up on the medication so we can go over what they’re used for and the directions. very important. Everybody calls me up after watching the videos and always wants to know what the dosages are for each medication. So we’re just gonna go over the dosages and try not to go into too much detail of why, okay?

Erythromycin, oxytetracycline, and Enrofloxcin are three antibiotics that are one gram with 40 gallons of water. You leave it in for three days. You don’t add any more, you don’t delete anymore. Three days, on the fourth day, you do a 30% water change. The process could be repeated a second time. I don’t recommend a third time because the antibiotics will eventually destroy your biological. So, we’re eradicating something external with those three.

Metronidazole, which there’s a video specifically to, is 1 gram for every 20 gallons. And the medication is added daily for 10 days. You can do your water changes prior to putting in the metronidazole or 8 hours after. And you do your water changes regularly. Remember, metronidazole deactivates in water.

Then we have the metronidazole in the food. People ask me how much, how much? Whatever you can grab with two fingers and put in the food. That’s how much. It’s a pinch. It’s not a specific measurement. We’re just gonna fold it into the food. We don’t wanna put too much into the food because it is bitter, and they may not wanna eat it. So, fold enough that they’ll get it in their system and clean out for that preventative.

Acraflavine Neutral

Acraflavine Neutral, which we use all the time when we move fish around. You can see that they’re in here. It relaxes them, and it’s antiseptic. So when they do get scratches, that scratch doesn’t turn into a secondary bacterial infection and catch fungus. Okay, we do that all the time. One gram, for 80 gallons of water, and you use one tablespoon of salt for every 40 gallons of water when you’re doing this type of medication. How long will it be active? As long as it’s green, it’s active. So, it’s gonna take you guys about a month. This particular batch right here we put it in six days ago, and you can see that the water’s still green. And we do 100% water changes daily. So it’s gonna take you a while to get this out. When using acriflavine, please be careful because it will destroy your plants. So if you’re gonna use acriflavine and try to use it in a quarantine tank or something where it’s away from everything, I’ve been told also that it will wipe out your shrimp. So be careful. We don’t have any shrimp here. So, you know, this is word of mouth that I’m hearing.


The metronidazole will not affect the plants, will not affect the other fish other than clean them out internally, so that one is safe. Oxytetracycline, Enrofloxcin and Erythromycin are all great. They won’t affect anything in the plant stage. They won’t affect the tetras. I know for a fact that guys use erythromycin to wipe out that blue-green algae. That’s also very good for that. Other than that, that’s about it on the medications. Very simple procedure, but please understand that when you’re using medications, please, like I say in the other videos, try to attack the problem with the proper medication. In other words, don’t take an Oxytetracycline sporadically because it’s not going to do anything for the disease. If you’ve got internal parasites, you don’t need acriflavine, you need metronidazole. If you’ve got wounds on the sides, scratches, or wounds caused by them whacking into things, the acriflavine will definitely help because it won’t let that secondary bacterial infection grow on there. It’s like putting triple antibiotic on a wound. It protects the wound from any secondary bacterial infection. Oxytetracycline is used when the anaerobic bacteria builds up too much and starts eating the fins on the fish. You can tell right away, like I said in the other videos, they start to look like sunflowers. That’s the only thing that will pretty much eradicate that in a heartbeat and let that fish heal on its own, where the fins will grow back. Sometimes you got two things going on at the same time. I like to treat the internal first, external second. You want that immune system to kick in. You want that food to be digested by the fish, not by the parasites. So, start the fish healing on the inside before you can heal it on the outside. Don’t mix the treatments. I don’t like to mix the treatments because you never know what the chemical reaction might be. You don’t want to turn something that’s very positive into something that’s very negative. Obviously, every single time you medicate, you have to take the carbon out. I am not a firm believer in using carbon in the tank for recycling. It’s not necessary. Common sense will tell you nobody changes the carbon in the Amazon River. Okay, it’s only water changes. You do your water changes, and you don’t need the carbon. Carbon, in essence, in our recycling tank, will dry out their skin. Remember, their skin slime is the front line of defense against bacterial attacks. So, if you’re taking that away from them, they’re going to be more susceptible to breaking down. These are little tidbits that I’ve gathered over the years on medications, treatments, and analyzing what the problem is. It’s very important. If you’re not sure, ask. It’s easier to ask and get it done correctly than it is to do something differently. If you have an internal parasite, and you decide to use antibiotics like oxytetracycline, all you’re doing is bringing down the immune system, and now the internal parasites will take over. So, you need to be able to attack. I’ve got clients that tell me that they use magnesium sulfate, which is Epsom salt, while they’re using the metronidazole. In a way, it makes sense because magnesium sulfate, Epsom salt, is like a laxative. So, it’ll make them defecate more. When you defecate more, and you’re medicating for internal issues, it’s a good thing to have because you’re getting rid of the internal matter quicker. Now, epsom salt is not regular table salt. I don’t want you to think that they’re the same thing. Sodium chloride is regular table salt. If you drink a cup of regular table salt with water, it’ll taste salty. If you drink a cup of Epsom salt, it’ll taste very bad, and you’ll be sitting on the toilet for the whole week.

As for baths for discus, I don’t believe in them. I know a lot of people recommend putting them in a 5-gallon bucket with epsom salt, dropping the fish in and getting them out. Epsom salt is a laxative, and if you’ve taken a laxative before, you know that it may not work the first day or the second day. My recommendation for you is to add one heaping tablespoon of epsom salt for every 20 gallons of water in the aquarium and leave it in for a week to 10 days until it does its job. A quick bath is not going to do the job. Leaving it in the water will. If you do a water change, you need to replenish what you took out. Remember, all salts leave the water column. It’s going to be active the whole time unless you do a water change, which means you’re taking some of it out. You need to replenish whatever you took out.

Regarding metronidazole, the number one question I get is how much metronidazole is needed. It’s one gram for 20 gallons. But if you don’t have a gram scale, you can take a little teaspoon and level it. One level teaspoon equals four grams. That means you can treat 80 gallons. So if you have a 40-gallon tank, it’s half a teaspoon. My suggestion is to buy a little gram scale so that you’re accurate, like us. Not all products weigh the same. Teaspoon of feathers and a teaspoon of lead take up the same volume, but they don’t weigh the same. Keep that in mind.

Potassium Permanganate

The potassium permanganate is the number two question that I get asked the most. I’m going to make it simple. If you don’t have a sump and you just have a couple of aquariums, get a bottle of water. 16.9 fluid ounces or 500 milliliters is half a liter. Break this one open, dump out a little bit of the water, and put 11 grams of potassium permanganate inside. This is your stock solution. When you make this stock solution, store it in a dark place because light destroys the formula. Now that you have a stock solution, get a syringe, and one CC on the syringe is used for every 5 gallons of water that you’re going to treat. So, if you’re growing out your discus in a 20-gallon tank, you’re going to use 4CC’s because it’s one CC for every 5 gallons.

I hope this information saves you a lot of time and effort in asking questions and emailing. For us, it’s simple because we have wet/dry systems, and we just throw it right in the wet/dry, and it goes through the entire system. “Will this kill the biological if you dump it directly into your filter? Yes, absolutely 100%. But by the time it reaches your filter, it’s already been deactivated. That’s why it turns brown. The idea is to kill all the suspended bacteria to protect your fish. We hope that we shed some light on your medication questions. I know I presented them quickly, but please continue to ask them as it gives us ideas for future videos. Once again, thank you. I’m Gabe Posada. Don’t forget to follow us on Instagram and Facebook. Since you’re already on YouTube, we look forward to making many more videos like this in the near future. Take care, guys.”

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Wattley Discus Admin


  1. pattyhru

    Thank you Gabe! Have a Merry Christmas and ignore my text! Must be aggravating being the Discus Guru for people like me that don’t take the time to research your material that always answers my questions!
    Thanks so much


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