Things like tarantula's, red, and blue corals are about the only thing that comes to mind for fishing schools. It's easier to farm mobs to get them though if you're just looking for +3s.

About the only thing that's worth getting is the lvl 36 guild mark abilities that up the chance for an HQ item. The crystal, stat boosters, and mob eluders are worthless.

http://www.disciplesoftheland.com/ pretty much has all locations of nodes and what you can get from them.