General question about antibiotic use

[DoctaReef]

Hi all
I have a new fox face in QT that is showing signs of bacterial infection: red patch on skin, sloughing of tissue.
I dosed the tank with Kanaplex, Furan-2 and Metroplex in hopes of saving him, but my question is this:
When it becomes time for the next dose, do you do a water change/add carbon to clear out the previous antibiotic in the water? Or do the antibiotics break down in the water, so just add the next dose in?
Thanks in advance!

 

[Malcontent]

They break down in water and are also metabolized by any higher organisms that absorbed them as well as microbes.

Otherwise you would only need a single dose.

I never saw the point in using carbon to "remove" drugs since they go away on their own. If the goal is to avoid subtherapeutic levels you would need to dialyze your fish too. The only scenario I can imagine would be a bad reaction to the drugs or OD, etc.

P.S. Kanaplex is under-dosed by 17-34 times compared to the doses in veterinary literature. That's probably why it rarely works.

 

[DoctaReef]

That’s what I thought, but I wasn’t sure how fast they broke down.

 

[Malcontent]

That’s what I thought, but I wasn’t sure how fast they broke down.

It really depends.

Nitrofuran is unstable when exposed to light and in water so it probably breaks down pretty fast.

Kanamycin has good persistence in water.

You can usually get an idea by searching for "[drug name ] environmental persistence."