My hypothesis is not that it does.
It is silly to think that antibiotics work differently if used in a food animal than it does in a pet. I'd love to know how the antibiotic knows if it is a fish raised for food or as a pet. If someone is going to make that claim they should offer some evidence.
They are different for a variety of reasons
First we are not eating them, thus exposing us to the antibiotics. By eating the antibiotic by eating the animal.
Second, for all intents, our fish populations are quarantined from spreading out into a general wild population. If, if your yellow tang develops an infection of antibiotic resistant pathogen. It’s not going to spread that pathogen to the larger yellow tang population. It just won’t(yes I know about lion fish off Florida).
Third, name one fish bacteria pathogen that is a pathogen to humans. Off the top of your head, no Googling. And, and is that bacteria affected by any of our in tank antibiotic interventions.
A single misused dose of antibiotics can create an resistance.
Not really. It takes one cell that develops resistance, to grow, multiply, carrying that gene for resistance, and colonize the host. Irrespective of that hosts immune system. In otherwords, not die by the hosts own immune system. Or by a bactericidal agent, say iodine.
Aside: I wonder if chlorhexidine can be useful in this hobby.
Antibiotic resistant bacteria are the greatest threat to people with compromised immune systems. HIV, AIDs, neutropenic, and people taking organ tissue anti-rejection drugs. Do you know any fish that have these conditions?
The vastest of vast of humans have immune systems that kill most MRDOs.
We care about the effects of resistance because of its effects on HUMANs. Not animals. And care about it only in animals only insofar that it affects humans.
(Ps, I am going to skip cross bacteria species transference and how that works)
I understand that you have a Nature Channel level of understanding of how MRDOs are made and spread. Which is more than most people. But it is not enough knowledge base or experience to be making accurate or precision opinions on the topic.
Get your old bio textbook out and go over the 5 steps of the Scientific Method. What they are, what they do, what their order is.
You have gone straight to step 5, Conclusion; missing all of the other steps.