It is indeed a tier two foragable so you can find them in either Antonica or Commonlands. In Antonica, the best place I have found is just off of the pier near the South gate.
Easiest way to go fishing here is to strap on an enduring breath spell, (either bring a priest or buy a totem of the otter), walk right off the end of the pier and then swim around under water till you find the fishing nodes. There are usually 3 or 4 of them clustered right around the pier and several more if you swim over towards the South gate.