Where to purchase Fresh Fish
Fresh Fish is a reagent used in a few different Tradeskill recipes, the ones we'll be focusing most on are the Brewing and Baking ones. Most commonly you'll find this item sold by Fishing Supplies merchants or Baking Supplies merchants. If Planes of Power is out on your server use Find to locate Klen or Culkin Ironstove as they have the Fish for sale.
There are more vendors that sell this item than shown on this page... If you'd like to see a complete vendor list for this item I recommend following this link to read the synposis on Eqtraders; however in the interest of saving you some time I have listed the best merchants to visit for this item below.
Chef Denrun, Culkin Ironstove & Klen Ironstove - Plane of Knowledge Baking Vendors
Klen Ironstove, Culkin Ironstove (not shown here) and Melet Ironstove are all available as early as Planes of Power - the same expansion that PoK goes live during. The other NPC shown in my screen shots above, Chef Denrun, is unavailable until the CoTF expansion pack.
These vendors sell basically every that is sold by vendors and used in the Baking profession. Chef Denrun has additional goodies which the others do not but not everyone can use him since he isn't available until so late in the game.
Umenon Clotius - East Freeport
Umenon Clotius is one of the few merchants that's available as early as Classic Everquest and that's fully stocked with basically every goody you'd need for Baking. This guy even sells stuff like Bear Meat, Lion Meat, Fresh Fish and other hard to find Baking Supplies.
Any Lake - Fishing
If it weren't already obvious another way for you to obtain Fresh Fish is by purchasing a Fishing Pole and some bait and going fishing. Most lake ponds and oceans have Fresh Fish in them - just don't fish anywhere too fancy with an odd loot table and you'll definitely catch some.