The Compleat Angler
This is surely one of the earliest books available to the modern angler. But it's worth distinguishing 'anglers' from 'fishermen'. I take 'anglers' to be people who go after fish for fun or sport or pleasure and 'fishermen' to be people who go after fish for work.
The first thing to be said about Isaak Walton's book, is that it is a play followed by a text book. The second thing, is that it's in a foreign language even to the English, because it was first published in 1653 when the author was 60. A ripe old age in England in those days.
Walton was essentially a biographer. He got paid for it - often commissioned as a good artist might. He wrote 'The Life of Donne' - a poet who even I've heard of. He's alleged to have been a prosperous merchant, but it doesn't really matter. Great angling writers like Richard Walker were engineers. Old school writers like George Skues, were public school educated solicitors in London practices who took the train to the chalk streams of Winchester in Hampshire at weekends, tying flies as they went.
The play concerns three people who meet by chance and get into conversation about their interests. They're travelling at a walk, and so they lighten their journey with convoluted conversation. Before long, it develops into a bit of a competition. Walton is the angler (Piscator). Another gentleman is keen on falconry (Venator) and yet another is keen on hunting (Auceps).
If you tire of 17th century banter, skip forward to the chapters on each particular species of fish, which will ring true immediately. To me it's a revelation that these friendly old fish will still fall for the same tricks as Walton was playing on there ancestors over 350 years ago.