No, they really aren’t.
Although it’s true that people and many animals are sometimes given the same antibiotic, they shouldn’t be shared or substituted between species.
www.fda.gov
They’re not evaluated for human consumption, do not have universal dosing standards across brands making it hard to calculate dosing, may not be produced in food/medication-safe facilities, and there is significant risk for cross contamination with dangerous chemicals. Not to mention there are medications to treat aquariums sans fish and there are medications to treat fish, and it’s very possible to make yourself ill if you take a medication meant to treat an aquarium as part of conditioning it to receive fish vs the same medication at a dose meant to treat fish. Especially with exotic fish, some aquarium medications are meant to be paired with water cycling as part of preparing it to receive fish. Even if it’s the same medication, an aquarium medication is a dose unsafe for fish and highly unwise for humans, hence the need for a different fish medication.
Really, let’s just stick with people medicine for people, animal medicines for animals. Were we in a Fallout 76-style nuclear apocalypse, sure, let’s see what we can do. But in 2023 with ready access to doctors, minute clinics, emergency rooms, and first responders, let’s just stick with people stuff.