Metronidazole

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Metronidazole (updated 1-11-23)

What It Treats:
Internal parasites (flagellates), Brooklynella, Uronema marinum* (tank cleansing only*)

* Metro is only suitable for eliminating Uronema from the water + tank surfaces. A fish infected with Uronema should be treated with formalin, or possibly Chloroquine phosphate. However, once red sores show up, or if a fish is infected with Uronema internally (intracellularly), the fish is generally considered to be untreatable. There are only a few anecdotal accounts of fish with red sores being successfully treated by using tea tree oil (Melafix).

How To Treat: It is best to use pharmaceutical-grade Metronidazole powder (sold here). Dosage is 25 mg/gal every 48 hours (or every 24 hours for severe problems) with a 25% water change before each treatment. Treat for 10-14 days.

Metro is the active ingredient found in Seachem MetroPlex, and also API General Cure & Fritz ParaCleanse. (Please note: General Cure and Paracleanse also contain Praziquantel.)

For Brook, dose metro directly into a quarantine tank every 48 hours for 10-14 days. For internal parasites, you have two options: (1) Dose the water every 48 hours for 2 weeks and hope the fish drinks enough of the medicated water to be effective. (2) Soak metro in the fish’s food. For the latter, I recommend using Seachem Focus** to bind the medication to the food. Feed daily for 2-4 weeks or until symptoms disappear. My recipe*** for food soaking metro can be found below:

1 tbsp food (preferably frozen food or pellets)
1 scoop (~ 1/8 teaspoon) of medication
1 scoop Seachem Focus (binder)
A pinch of Epsom salt to help expel dead worms/parasites

Several drops of saltwater or fish vitamins to wet everything down
Stir until a medicated food slurry has been achieved
Feed after soaking for 30 mins

Refrigerate or freeze any leftovers for future use

**
Agar or unflavored gelatin can be used in lieu of Focus. More medicated food recipes can be found here: How To Make Medicated Feed

Whether or not metro is “reef safe” is a topic for debate. I personally feel that soaking it in fish food is an acceptable risk; whereas dosing it directly into the water column IS NOT and should only be done in quarantine (or a FOWLR).

Pros: Metro is generally well tolerated by most species, and can be soaked in fish food (making it reef safe). However, Seachem Focus** needs to be used to prevent the medication from leaching out. Also, it is a good idea to run carbon just in a case.

Cons/Side Effects: It is rare, but every now & then I run across a particular fish that seems to have a negative reaction to metronidazole.

*** The "proper way" to food soak medications is by weight. (Some sources say to weigh the food, some even say to weigh the fish. :eek:) I find this to be impractical for the casual hobbyist, and that my "shotgun approach" to food soaking medications generally works. However, for those who wish to food soak Metronidazole properly it should be dosed in food at 0.50% by weight. There are oral dosages listed here (Table 1) for other medications: CIR 84/FA084: Use of Antibiotics in Ornamental Fish Aquaculture
 
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JF47

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Hi, in this treatment with Metronidazole you say "1 tbsp food (preferably pellets or frozen food)". I currently have a few fish in QT that right now refuse anything other than flakes for some crazy reason. I usually feed frozen foods almost exclusively and I can't say I have ever had a fish that only wants flake. I can't get them to eat much else, but I need to treat internal parasites as one definitely has it. I want to add General Cure to their flake food while I transition them to other foods, but I'm concerned they won't get the proper amount of medication. Is it still 1 Tbsp of food if it is flake, or should it be some other number (perhaps by weight instead of volume)? On a related note, should I use something like alcohol to dissolve and bind it with the focus to the flake and let it dry out to create a dry batch to store and use, or would using Selcon and/or saltwater be enough?
 

Humblefish

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@JF47 Pellets would be better as those are more porous and thus would absorb more of the medication. Whenever I’ve tried using flake w/meds, it just gets all mushy and the fish refuse to eat it. But it’s worth a shot to try.

Dosage would be the same (1/8 tsp of medication per 1 tbsp of flake), and no need to use alcohol as metro will dissolve in a few drops of SW after about 30 mins. We don’t want to get the fish drunk. ;)
 

JF47

New member
@JF47 ...Dosage would be the same (1/8 tsp of medication per 1 tbsp of flake), and no need to use alcohol as metro will dissolve in a few drops of SW after about 30 mins. We don’t want to get the fish drunk. ;)
Thank you! I got the idea for disolving with alcohol here http://www.hikariusa.com/articles/medicatedfeed.html You would mix it in and then let it dry off so as to not introduce it to the fish much (if any). I am also concerned it will get mushy, but I'll try it tonight and see. Thanks again!!
 

Humblefish

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Thank you! I got the idea for disolving with alcohol here http://www.hikariusa.com/articles/medicatedfeed.html You would mix it in and then let it dry off so as to not introduce it to the fish much (if any). I am also concerned it will get mushy, but I'll try it tonight and see. Thanks again!!

That's interesting about letting the alcohol evaporate. I may try it. Let us know how you get on with using flake food.
 

JF47

New member
...Let us know how you get on with using flake food.
A quick one day update on using flake. I used flake, Focus, and GC mixed in a small container and shaken to mix. I then added a fair amount of Selcon, shaking between drops, to wet the flake and shook it around a bit more to get everything binding. It was fairly damp and clumpy, so I tried a quick low heat in the oven to dry it, but that was taking forever. I switched to just a few seconds in the microwave with paper towels top and bottom which worked much better. I broke it up from the clumps afterward and stored it in the container in the fridge. I probably went too long on the microwave (cooked it a bit and the smell wasn't exactly great), and I hope that didn't impact the potency of the medication, but nothing I read said heat would be an issue for it. If you think heating it could be a problem then I will have to try another way I suppose. I don't have access to the alcohol that link recommended (at least not without ordering online, paying a lot and waiting a week).

All that said, I fed it to them this morning and they all ate it without much trouble except for pieces where I had not really broken it up enough for them first.
 

Humblefish

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I probably went too long on the microwave (cooked it a bit and the smell wasn't exactly great), and I hope that didn't impact the potency of the medication, but nothing I read said heat would be an issue for it. If you think heating it could be a problem then I will have to try another way I suppose.

Heat and sunlight can degrade medications whilst they are still in powder form. I store all my meds in a freezer to prolong their shelf life.
 

Corey

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With Metroplex dosing in water. Do you do a water change after each 48 hour treatment, for 14 days? Treating as a precautionary. Thanks
 

Humblefish

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With Metroplex dosing in water. Do you do a water change after each 48 hour treatment, for 14 days? Treating as a precautionary. Thanks

It's not necessary to do a water change before each metro dosage. Most of the medication will have dissipated out after 48 hours anyway. I would do a large water change at the end just to remove any lingering residuals.
 

saltyanimals

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Researching for my own potential brook issue. I'm seeing brook on some anthias in DT. Not able to remove for proper QT and dose metro in the water reading above where it's not reef safe. Would metro focus food be a treatment for brook? Reads internal parasites above, but what are the options for in reef tank metro treatment? Note that I'm doing H2O2 in-tank treatment and it's not working for me against brook for those on the large H2O2 thread.
 

Jessican

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I know I saw posts on R2R where people were using metro to try to combat dinos, and at a higher dose than we use in QT, with no ill effects on the system. We discussed it some in this thread: What am I dealing with here? (Dosing H2O2 in the DT to treat parasites)

I personally think it could be considered reef safe, which is why we’re able to use General Cure-soaked food in a DT without a problem (I don’t think focus really binds that well, which is why food soaking fenbendazole still resulted in me losing a bunch of coral, so it seems to me like GC just doesn’t have a negative effect). @Humblefish what are your thoughts?
 

Jessican

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Pretty sure metro is effective against velvet which is a dino.
Per @Humblefish this is the problem with trying to use it for velvet:

Metro in the water will kill free swimmers the same as copper or Chloroquine. However, the kicker is it has to be at therapeutic and metro usually decomposes within 24 hours. (Sometimes a lot less than that.) So, there will be lapses in coverage before you can safely redose again.
 

Humblefish

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I personally think it could be considered reef safe, which is why we’re able to use General Cure-soaked food in a DT without a problem (I don’t think focus really binds that well, which is why food soaking fenbendazole still resulted in me losing a bunch of coral, so it seems to me like GC just doesn’t have a negative effect). @Humblefish what are your thoughts?
I feel General Cure is probably reef safe (with caution), as both of the active ingredients it contains (praziquantel & metronidazole) have been dosed separately & successfully in a reef environment before.

But what it's going to take is enough people willing to try it, with various corals/inverts, and report back with their results. To form a consensus. I'm sure the first time someone decided to try dosing Prazipro in their DT they were nervous as hell... :p
 
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