Levamisole and metronidazole question

[chickennublet]

Hello all

Would like to do a round of deworming on my tank (and another round if required) because I recently acquired some Corydoras CW51 and my stupid ass decided to take a gamble and not quarantine them. Only two appear to be unhealthy (one I've already had for a year and only recently started looking scruffy the other for slightly less than 2 weeks) but they are Corydoras so they are probably harbouring some worms in them.

I have done one round of metronidazole (but only in the water as I didn't have the time to mix it into food, have to rush off for work in the morning and get home quite late sometimes) and praziquantel and will probably repeat again as required, and as far as possible will soak some food in the metronidazole this time. Before that, I want to follow up with levamisole.

Wanted to ask these questions:

1. is metro only effective when ingested and completely useless dosed in water? Or is it at least a little beneficial?
2. does levamisole kill internal worms or does it only paralyse them so that the fish can excrete them?
3. any alternative dewormer I could use that won't outright kill neocaridina shrimp?

Reason for question 2 is that the tank is full of plants and hard to reach areas and even with a big water change and cleaning the sand I will likely miss out some worms unless I were to remove all the plants and hardscape beforehand which I would like to avoid.

Would be very grateful for advice. Thank you!

 

[rockpaper]

Since no one has answered you yet, I figure I could give it a shot. Please know I am a novice hobbyist, so my practical knowledge is limited. My strength is that I am a molecular biologist and I can access, read, and understand scientific literature... so I guess, I can tell you what papers say, but I don't know how it applies "in the real world"? Take the info as you will.

Your questions:

Q1.
Depending on the type of parasite your fish are suffering from, external metro might work, but likely only if the parasite itself is external. I will also mention that metro is an antibiotic and antiprotozoal, but I don't think it's a good de-wormer per se... I am not exactly sure, but the answer might be "it could help, or it could do nothing" depending on your situation.

And while I am not sure about efficacy, I do know metronidazole is highly water soluble and persistent in aquatic environments. This paper from 2005 showed that metro is fairly stable in-solution, even at high temperatures, in light, and exposed to air. The authors saw only a 2-4% decrease in the concentration of metro in aqueous solution over the course of two weeks. The degradation is not linear, but without intentionally removing the metro, it could take months to a year+ for it to degrade on its own.

Metro is a broad-spectrum antibiotic, and if I had to guess (which I do because I'm new at this and a dummy), the real problem with putting it in the aquarium water might be that it is overkill. This paper from 2022 explores the effect of metro on our biological filter, saying "nitrate-nitrogen removal efficiency decreased from 97.98% to 89.39%, 86.93%, 82.64%, and 82.77% within 12 h after the addition of 1, 3, 5, and 10 mg/L [metro], respectively". It also affected the biodiversity of the filter they tested, selecting for microorganisms that used nitrogen-removing metabolic pathways that were more effective under the medicated conditions. I am not sure what dose you used for your fish, but I think being careful about the filter in the short term is a good idea.

Thankfully, the prior mentioned paper found that the biological filter itself does do a decent job of removing metro (with their specific type of filter removing almost all of it after 6 hours), although at the cost of the nitrogen removal capacity. And, another paper reviewing how to remove metro from aqueous environments found that activated carbon seems to be a fine enough way to remove it from the aquarium. One reviewed paper saw 90% removal of metro using 1g/L of activated carbon... That may or may not be an impractical amount of carbon to add to a filter all at once depending on your setup, but you could probably space it out in several "doses" to remove it entirely.

Q2.
Levamisole is such a weird drug that it is hard to find clear answers on this question-- not that they don't exist, but that it is more annoying to figure out than a few minutes of scrolling literature databases would definitively tell me. Part of the problem is that we have recently discovered that it does a lot of other stuff we didn't know about that has implications for immunoregulatory and/or anti-cancer purposes, so like, all the literature is about that and not as much about worms anymore.

I will say that from what I can casually glean, it seems like yes, levamisole does actually kill the parasites... by paralyzing them.

Q3.
I think you probably want to be a little more certain as to what kind of parasites you think your fish have, because these drugs can be powerful and have unintended consequences (like maybe hurting your filter). Still, as one potential alternative, I just wrote a report of my experiences researching and using fenbendazole to rid my tank of hydra, which could technically be an option for a de-wormer that won't harm shrimp (but will harm snails). I think using it the way I did would only work for external worms, however!

I feel kind of bad because I realize this wall of information might not actually be all that useful for you... But, hopefully you can get some food for thought about your next steps.

Hope your corydoras feel better soon!

 

[chickennublet]

Since no one has answered you yet, I figure I could give it a shot. Please know I am a novice hobbyist, so my practical knowledge is limited. My strength is that I am a molecular biologist and I can access, read, and understand scientific literature... so I guess, I can tell you what papers say, but I don't know how it applies "in the real world"? Take the info as you will.

Your questions:

Q1.
Depending on the type of parasite your fish are suffering from, external metro might work, but likely only if the parasite itself is external. I will also mention that metro is an antibiotic and antiprotozoal, but I don't think it's a good de-wormer per se... I am not exactly sure, but the answer might be "it could help, or it could do nothing" depending on your situation.

And while I am not sure about efficacy, I do know metronidazole is highly water soluble and persistent in aquatic environments. This paper from 2005 showed that metro is fairly stable in-solution, even at high temperatures, in light, and exposed to air. The authors saw only a 2-4% decrease in the concentration of metro in aqueous solution over the course of two weeks. The degradation is not linear, but without intentionally removing the metro, it could take months to a year+ for it to degrade on its own.

Metro is a broad-spectrum antibiotic, and if I had to guess (which I do because I'm new at this and a dummy), the real problem with putting it in the aquarium water might be that it is overkill. This paper from 2022 explores the effect of metro on our biological filter, saying "nitrate-nitrogen removal efficiency decreased from 97.98% to 89.39%, 86.93%, 82.64%, and 82.77% within 12 h after the addition of 1, 3, 5, and 10 mg/L [metro], respectively". It also affected the biodiversity of the filter they tested, selecting for microorganisms that used nitrogen-removing metabolic pathways that were more effective under the medicated conditions. I am not sure what dose you used for your fish, but I think being careful about the filter in the short term is a good idea.

Thankfully, the prior mentioned paper found that the biological filter itself does do a decent job of removing metro (with their specific type of filter removing almost all of it after 6 hours), although at the cost of the nitrogen removal capacity. And, another paper reviewing how to remove metro from aqueous environments found that activated carbon seems to be a fine enough way to remove it from the aquarium. One reviewed paper saw 90% removal of metro using 1g/L of activated carbon... That may or may not be an impractical amount of carbon to add to a filter all at once depending on your setup, but you could probably space it out in several "doses" to remove it entirely.

Q2.
Levamisole is such a weird drug that it is hard to find clear answers on this question-- not that they don't exist, but that it is more annoying to figure out than a few minutes of scrolling literature databases would definitively tell me. Part of the problem is that we have recently discovered that it does a lot of other stuff we didn't know about that has implications for immunoregulatory and/or anti-cancer purposes, so like, all the literature is about that and not as much about worms anymore.

I will say that from what I can casually glean, it seems like yes, levamisole does actually kill the parasites... by paralyzing them.

Q3.
I think you probably want to be a little more certain as to what kind of parasites you think your fish have, because these drugs can be powerful and have unintended consequences (like maybe hurting your filter). Still, as one potential alternative, I just wrote a report of my experiences researching and using fenbendazole to rid my tank of hydra, which could technically be an option for a de-wormer that won't harm shrimp (but will harm snails). I think using it the way I did would only work for external worms, however!

I feel kind of bad because I realize this wall of information might not actually be all that useful for you... But, hopefully you can get some food for thought about your next steps.

Hope your corydoras feel better soon!

Thank you!

Yeah I did get a bit concerned after finding out that metronidazole is an antibiotic. I used it a couple of times because I didn't want to accidentally create something resistant to it. I do think it will help get rid of some parasites but not worms specifically. I probably won't be using it in the display tank again that soon. I will probably still use it when quarantining new fish though.

I bought the medicine which I suspect contains levamisole in it. I don't actually know what the active ingredient is but the directions say to turn off the lights so it must be light sensitive but i'm not sure if levamisole is light sensitive or not. I haven't used it in the display tank, but I did use it in the quarantine tank and didn't see any reaction from my Corydoras. I also didn't see any dead worms in the tank, so i'm going to assume that he's fine now.

I did consider looking for a fenbendazole product but I didn't want to deal with dead snails in my tank. I don't have any snails in there that I added on purpose and want to keep, but there are a number of really tiny little snails and I don't want them all dying at once. Will take a look at your thread in case I ever need a de-wormer.

 

[dw1305]

Hi all,

Yeah I did get a bit concerned after finding out that metronidazole is an antibiotic.

Antibiotics (for both human and pet health) can't be bought over the counter in the UK, they are prescription only. I wholly agree with this, as there is an almost perfect correlation between <"antibiotic use and antibiotic resistance">.

In the UK we still <"have the farming issue">, where antibiotics are (illegally) used prophylactically on Pigs, Chickens etc.

Metro is a broad-spectrum antibiotic, and if I had to guess (which I do because I'm new at this and a dummy), the real problem with putting it in the aquarium water might be that it is overkill. This paper from 2022 explores the effect of metro on our biological filter, saying "nitrate-nitrogen removal efficiency decreased from 97.98% to 89.39%, 86.93%, 82.64%, and 82.77% within 12 h after the addition of 1, 3, 5, and 10 mg/L [metro], respectively". It also affected the biodiversity of the filter they tested, selecting for microorganisms that used nitrogen-removing metabolic pathways that were more effective under the medicated conditions.

That is definitely a problem. I'd really strongly recommend that people don't use antibiotics in their fish tanks, even in the countries where you can buy them "over the counter".

Personally I'm only going to take them if a clinician insists that I do, because my gut microbiome is in a healthy state and <"I'd like to keep it that way">.

cheers Darrel

 

[chickennublet]

Hi all,

Antibiotics (for both human and pet health) can't be bought over the counter in the UK, they are prescription only. I wholly agree with this, as there is an almost perfect correlation between <"antibiotic use and antibiotic resistance">.

View attachment 219952
In the UK we still <"have the farming issue">, where antibiotics are (illegally) used prophylactically on Pigs, Chickens etc.

That is definitely a problem. I'd really strongly recommend that people don't use antibiotics in their fish tanks, even in the countries where you can buy them "over the counter".

Personally I'm only going to take them if a clinician insists that I do, because my gut microbiome is in a healthy state and <"I'd like to keep it that way">.

cheers Darrel

Interestingly in Singapore antibiotics for humans and pets cannot be purchased over the counter and are prescription only. But somehow we can buy medicine for fish that contain metronidazole, kanamycin, erythromycin and the like at pet shops.

 

[illumnae]

Did you manage to treat your cories? I got 50 pcs of the cw51 from the 2 shipments from qianhu last month and they were pretty healthy. I did deworm them with metronidazole, praziquantel and levamisole as a preventive but they didn't excrete any dead parasites out so I don't think internal parasites is your issue. I did notice some from the 2nd shipment were lethargic (and I was told half the shipment died in qianhu's holding tanks) but I think it was a bacterial issue not internal parasites. Mine perked right up after a course of antibiotics - I do a preventive course of DiscusX Bactocide 1 and 2 for all tankmates going into the display tank with my discus.

 

[simon_the_plant_nerd]

Interestingly in Singapore antibiotics for humans and pets cannot be purchased over the counter and are prescription only. But somehow we can buy medicine for fish that contain metronidazole, kanamycin, erythromycin and the like at pet shops.

Years ago, in the UK, I bought some fish medication from eBay. The seller was very quick to point out (without asking) that they were antibiotics and “exactly the same” as what I could get from the doctors “safe for use on humans”. I asked if they were appropriate for fish, as the listing described and he replied “don’t know. I give them to my daughter.”