Amazon has a ton of listings for "fish antibiotics" whose reviews reveal that the people who buy them are self-medicating because they can't afford a doctor's visit because they are uninsured or can't afford their insurance's co-payment.
Some purchasers appear to be preppers, stocking a pharma larder for the end-times; others are hypochondriacs or self-diagnosers who are frustrated that they can't get antibiotic prescriptions out of their doctors.
This is a terrible idea.
Self-medicating with unregulated online antibiotics exposes you and the world to serious risks: there could be anything in those bottles; the dose is hard to get right; if you're taking it improperly you can exacerbate the growing problem of antibiotic resistance; and even if you have a bacterial infection, the fish antibiotic you're taking might not be the right one to treat it.
This isn't limited to Amazon: a search of the web reveals many other forums where people are taking animal medicine because they can't afford health care.
Sharp suggested that people taking antibiotics meant for guppies is a sign of how inaccessible and expensive American health care has become. In fact, some reviews even allude to this, noting that the fish pills are a "great alternative to racking up debt at the fish hospital."
Though generic antibiotics are often very affordable, or even free, at pharmacies, the cost of visiting a doctor to get a proper prescription can be prohibitive for some people, particularly people who don't have health insurance. Studies have shown it's common for people to keep old prescriptions of antibiotics to use in the future without a diagnosis, or even take their pets' antibiotics.
People Are Buying Fish Antibiotics Because They Can’t Afford Human Ones
(via Naked Capitalism)