It's Time: THE TACKLE BOX.

[Elamys]

As a max level fisher myself (On V'nesh Aevingale) I do a lot of catching specific fish for certain recipes, certain desynths, mooches, pets - helping people catching their quest fish; certain oils for alchemy - specific housing items or gear pieces. It requires a LOT of specific bait when you're going after specific fish. The catch all bait just doesn't do it. The catch all bait is great if you're just going after achievements for catching all of the different kinds of fish at a particular fishing hole: But it's NOT good when you're going after specific things.

So why can't you purchase the bait as needed? Most of the baits can even be purchased at the same aetheryte you'll be teleporting to.