There’s an old fishing expression, “it’s not the length of the worm that matters but how you wiggle it that matters”. The list of fish needed for each region is well known (see journal, achievements, trophies, fishing) but not the water type of each. Fortunately, that’s where this tome fills the gap.
There are 25 different fishing achievements up for grab in Tamriel. One for every region. One for every faction. One for getting them all. Aside from a sense of great accomplishment, the fisher is bestowed the title of Master Angler and unlocks several new colours for dyeing equipment. The uncommon fish (green) have a vendor price of 36g and the rare fish (blue) a price of 110g.
This document lists all of the rare fish in each region and which body of water they can be found. In some regions without a certain water type, the rare fish are divided by the remaining water types.