I've been doing a lot of correcting lately. Awards, personnel actions, command memos, policies, all the things. While I wouldn't necessarily think of this as a fountain pen job, the only pen I had with a fine enough point and a colored ink that I thought was visible was one of my Pilot Petit1's (green).
This got me thinking, and ordering samples of an array of colors to try out for testing.
I tend to prefer not-red for corrections as red seems to spawn visceral hackle raising, so mostly I'm looking at turquoise blues and greens, though I'm not wedded to that.
Requirements, for me, for a correcting ink are that the color is bright and easy to see against black printed text, even if it's just a little comma. It has to not bleed terribly on decent but not fancy printer paper (laser).
The generic Pilot green does well but is a little pale and feathers a little. Right now I'm working with Noodler's Gruene Cactus Eel, which I like better, but the "eel-ness" means it dries pretty slowly (something I hadn't even thought about until I used it).
What inks do you like using for corrections? I'm thinking of trying J Herbin Vert Pre or Diamine Kelly Green next.