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Praziquantel, lifetime in aquariums


AlanM

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I'm holding my fish in a small treatment/observation tank until my large aquarium upgrade is ready.  In the meantime I saw what looked like some stringy poo coming from one of the clownfish which were never really treated for anything, so I decided to try treating first with PraziPro which is praziquantel since it is apparently well tolerated by fish and nearly impossible to overdose.  I had been reading about it and came across this interesting study.  I assume the full text is open to everyone and not just from my lab:

 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4824874/

 

Their conclusion is that prazi is metabolized by some microbial contents in an aquarium, some components of the bio-film can use it, apparently, so the first time you use prazi in an aquarium it lasts around 9 days, subsequent times it can be gone to below therapeutic levels (2ppm) in as little as two days or maybe even less.  In a totally sterile system it lasted for as long as 15 days in their study.  One of the poster presenters at MACNA 2016 from Georgia Aquarium was measuring it drop to 0 after 15 hours in their large systems.  

 

Just thought it was pretty interesting and possibly relevant to anyone treating fish with prazi.

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The paper is visible to the public. :thumbsup:

 

That's a huge variation in lifetime: 15 hours to 15 days? How is the average aquarist, who probably doesn't have a means to measure praziquantel in their treatment tanks, to measure to maintain therapeutic levels? I mean, if you dosed every 15 hours, you could wind up with more than 20x in some tanks at the end of 15 days. (You say difficult to overdose, but 20x seems extreme.) The only thing I might suggest given this is to sterlize treatment tanks (bleach and water?) (so you kill off any bacterial film that might metabolize the praziquantel) before each use and dose as much as every 5 days or so.

 

Depending upon how fast a new bacterial film might mature, you may have to run the fish through a series of sterilized tanks if treatment is needed over a longer period of time.

 

Thoughts?

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Well, I don't know how long a time is required for treatment to be effective on the targeted pests.  I want to ask that person with the poster at MACNA if they were removing it intentionally within the 15 hours or not, but can't find her contact info. It's interesting that she was working at Georgia Aquarium and the folks in the study I linked sent their samples to the Georgia Aquarium to be tested.  They must have a rep for owning the equipment needed to find prazi.

 

Hikari says a single treatment of 5-7 days works but you can dose every 3-5 days so they must know that the decay period is around that timeframe, I think, and snorvich on reefcentral and HumbleFish on Reef2Reef who seem to be reasonable experts on the topics seem to accept those directions as effective from their observations.

 

I was surprised at how thick the prazipro brand stuff was.  So far no fish are reacting badly to it.

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I can't seem to find where I read it, but I had a similar issue a few years ago and read that diet my contribute to white stingy poo in clownfish.  The article if I recall correctly specified feeding a diet high in Mysis shrimp could cause it.  FWIW I have had that clownfish for a few years now, never been treated either and has the occasional stringy poo.  Interested to hear your results. 

Edited by ReefAddict
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thanks for the share alan. this is something often missed by shops and hobbyists that set up long term qt/hospital systems. it's always good idea to get the specifics on the quarantine and treatment protocol before acquiring fish to ensure proper diligent methods are being used.

the problem is that after several months of using the same hospital tank/system, praziquantel and other medications do not remain at therapeutic levels long enough to be effective, as you state.

this is because as heterotrophic bacteria begins to build-up in the system they will bio-degrade most medications. in long running systems, this can happen at a frightening rate, certainly. heterotrophs can do this with praziquantel but it is not limited to this treatment. the same applies to antibiotics, chloroquine phosphate, etc. 

 

bleaching the system to sterilize it every couple months help manage the heterotroph populations and one can avoid these issues.

 

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Thanks, Marco.

 

In the article at pubmedcentral I linked they did bleach their tanks to try to prevent the biofilm from consuming it, but it still did in short order. They guessed that the film has a resilient surface to the bleach and more extreme treatment would be needed to get rid of it, but aren't sure and propose further research to find what is happening.

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Well, I don't know how long a time is required for treatment to be effective on the targeted pests.  I want to ask that person with the poster at MACNA if they were removing it intentionally within the 15 hours or not, but can't find her contact info. It's interesting that she was working at Georgia Aquarium and the folks in the study I linked sent their samples to the Georgia Aquarium to be tested.  They must have a rep for owning the equipment needed to find prazi.

 

Hikari says a single treatment of 5-7 days works but you can dose every 3-5 days so they must know that the decay period is around that timeframe, I think, and snorvich on reefcentral and HumbleFish on Reef2Reef who seem to be reasonable experts on the topics seem to accept those directions as effective from their observations.

 

I was surprised at how thick the prazipro brand stuff was.  So far no fish are reacting badly to it.

 

Alan, send a note to Kevin (MASNA). He should have contact information for the poster session.

 

When scanning the article, I noted that Disney received a nod for funding provided. Certainly Epcot has a large aquarium on site that would benefit from the study results.

 

If you reach out, ask if they controlled the bleach treatment (concentration, time, temperature) or if they tried varying it to see the difference. It would be an interesting result to have.

 

I recall their being one experiment, quite possibly this one, that used a different measurement (HPLC?) column that was significantly more cost effective than previous approaches and that the experiment followed after discussion of the product with that company's representative. There were significant savings involved, I think, in using the newer equipment. Is this that experiment?

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Yep, that was the poster from MACNA. I got the contact info from Kevin and contacted her. Then I contacted the lead author from the pubmedcentral article who was at Disney. No return email yet.

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I heard back from Kailen, who presented the new measurement technique at MACNA.  At the Georgia Aquarium they always test for concentrations frequently because it breaks down so quickly on systems that see it regularly.  In extreme cases they see it completely gone in "hours".  Since it's impossible for us to test for it, maybe it's not even appropriate to rely on in our aquariums to control parasites unless they are killed very quickly (less than a day seems necessary) before the concentration can drop.

 

The Disney folks bleached their aquariums at 75ppm and 200ppm chlorine and it didn't prevent the breakdown.  Here's what they said:

 

In this study, the biofilm is thought to have survived 24 h at a concentration of 200 ppm Cl and then released microorganisms back into the systems that were able to degrade PZQ in three days. The dynamics and likelihood of this hypothesis are unknown at this time, but studies investigating the rate at which a biofilm can re-colonize a system with microorganisms that can metabolize PZQ are needed to substantiate this claim.

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I heard back from the head of research at Disney's aquarium on how they clean treatment tanks between PZQ uses.  Here's what he said:

 

From our research the only way to tackle the biofilm is detergent, alcohol, and possibly H2O2. Ideally you would find a fish-safe detergent followed by 20 min alcohol application. H2O2 would be a second choice but don't know concentration or contact time. Bleach is no good in this situation. Every system is different. Good luck! 

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Great. I remember back in the day when we were breaking down cell walls for my genetics professor, we used lemon-fresh Joy (a detergent). So this makes sense and brings back a few memories.

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i don't think we are trying to kill the bacteria 100% which can only really been done by desiccation - breaking down the systems, draining, and air drying. this would only work because you have effectively eliminated the environment of the bacteria.

so if one is going to properly treat their fish and have long running systems without breaking them down we can knock back their populations as to minimize the interference they have on medications we use. antibiotics are short-lived in water anyway and chemicals like formalin and acriflavine are best administered in a short bath solution instead of directly to the system. thankfully, praziquantel only needs max 24-hours to force the worms to dislodge from the fish. in actuality, this is probably accomplished in just a few hours.

 

something to consider is folks using chloroquine phosphate, which needs to be maintained at a continuous therapeutic level in order to be effective. one can only blindly bet they are keeping levels therapeutic through the system but use of a  spectrophotometer would be needed to know for sure.

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