Hah, I might not be the best to explain Amiga history, but I’ll do my best :) Fish disks were the main way to distribute public domain, open source, shareware etc. before the internet was wide-spread. People would send Fred Fish software, and he’d compile them into individual disks that people would copy. Magazines would have lots of companies that would allow you to order copies of these disks etc. He ended up creating over a 1000 disks this way. When cd-roms became a thing, you could order the whole collection on those. Those were strange times :)
Aminet was the most famous ftp-archive for amiga software. It was run by the same guy that made Brainfuck, Urban Müller. Rather than chronologically like fish disks, it was organized by topic, with readme’s for every file. You could upload to a staging area, and he’d put them in place. Much like fish disks, companies would print cd-roms with the latest from aminet for those not hooked up to the internets (or on 56k modems, which was most people).