Warning! Formaldehyde can be very toxic in aquatic environments

Discussion in 'Fish Disease Treatment and Diagnosis' started by Lasse, May 16, 2019.

  1. Lasse

    Lasse Valuable Member R2R Supporter R2R Excellence Award Reef Squad Leader Reef Tank 365 Article Contributor Build Thread Contributor

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    I have understood that some fish "medicines" can still contain formaldehyde. I thought it not was in use any longer. Besides effects on humans (supposed cancerogenic and other effects) it can convert to a very toxic substance paraformaldehyde with time, especially toxic for fish. It is not question if – the question is when? Old batches can have formed paraformaldehyde and if it have been stored below 5 degree C - even fresh formalin can convert to the toxic form.
    However – there is a chance to see this. Good formaldehyde is a clear liquid without any cloudiness – if you can see precipitation in one or another way – paraformaldehyde has been formed. If the bottle contain formaldehyde and show precipitation DO NOT USE IT

    More reading here

    Sincerely Lasse
     

  2. ngoodermuth

    ngoodermuth Valuable Member R2R Supporter R2R Excellence Award Reef Squad Reef Tank 365 Hospitality Award Build Thread Contributor

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    I’ve yet to touch the stuff. I’ve been able to find a suitable alternative in every case so far, and generally discourage using it whenever possible.

    This is a great heads-up regarding the medication “turning” to the more toxic form.... I honestly didn’t even realize that could happen until you’d mentioned it in another thread.
     
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  3. Big G

    Big G captain dunsel R2R Supporter R2R Excellence Award Reef Squad Hospitality Award Build Thread Contributor

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    Have one of the last bottles of Formalin. I avoid it unless drastic measures are needed to save a fish. The possible side effects always give me pause.
     
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  4. Lasse

    Lasse Valuable Member R2R Supporter R2R Excellence Award Reef Squad Leader Reef Tank 365 Article Contributor Build Thread Contributor

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    Be carefull - old - probably some paraformaldehyde in it. If you should use it look very carefully for precipitation. If it have that - away with it.

    Sincerely Lasse
     
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  5. rkpetersen

    rkpetersen walked the sand with the crustaceans R2R Supporter R2R Excellence Award Reef Squad Partner Member 2019 Controller Advisor

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    I have formaldehyde/formalin 'on hand', but have never used it on fish.
    When I was a kid and very interested in microscopy, I used gallons of formalin to preserve specimens, lol.
    And then I worked in an autopsy lab for a while and the entire place smelled of it.
    I even rather liked the smell.
    Was also very interested in chemistry when younger and frequently used carcinogenic benzene as a solvent.
    No cancer yet. ymmv. :)
     
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