Maybe. My reading is that Midland Vet isn't following the FDA approval process, which is a straightforward way to get shut down. Second is just a blanket statement about antimicrobials, but not really backed by evidence for our particular use case, to my knowledge (which may be lacking). I agree that inappropriate use is a risk for AMR, but I don't know if our use is inappropriate. Does anyone know?
Antimicrobial resistance isn't something that just happens. Environmental conditions must be met and the microbe must have a mechanism for acquiring or developing the resistance. Take syphilis which remains largely susceptible to penicillin vs. Streptococcus pneumoniae, which has been steadily increasing in resistance. Streptococci can be pass genetic information between some species in a promiscuous way which is an easy way to pass on a resistance gene from one to another--in their case, sharing is caring. The syphilis bacterium is a spirochete that doesn't have plasmids which might be a reason they haven't transferred resistance between strains as easily. What's in your fish tank is a whole world of unknown. Further, the environment has to support the need for keeping resistance genes. Maintaining resistance can be an evolutionary disadvantage if there is no need for it to survive. Take chloroquine resistance in parts of Africa, where parasites have been reverting to susceptible phenotypes after long-term cessation of chloroquine use.
So that begs what I imagine is an unstudied question. Does the amount of cipro that we put in our tanks (which is far less than you put in your body for an active infection), that is subsequently flushed and entering into the wastewater system, causing bacteria to acquire cipro resistance in order to survive?
Note, when I do in tank treatment, I am only removing a small amount of extremely diluted cipro that has been in the tank for many days and likely degraded, and carbon is off during the treatment period, but back on before a water change. I don't do cipro dips (then flush), but that could also be mitigated if proper caution were taken.
My current hypothesis that I have no plans on testing: cipro that goes from hobbyists' fish tanks into the wastewater system is inactive and so dilute that antimocrobial efficacy is nil and the wild type bacterial population persists.