Take note, there are two different types of Indigo Herring, as such this topic was initially started for the old ones (long before hamlet came out).
(new ones have now been renamed to Young Indigo Herring, but still confuses many people as when they were first released, were called Indigo Herring, same as the old ones. One way to check which you have, is open the use menu (where you eat food, use potions, crafting manuals etc. if the herring shows up there, it is the old style herring used for crafting. Whereas if it does not show up in that list, you have the Hamlet provisioning item.)
The hamlet ones are found south of Bald Knoll, in schools on, and you can catch up to 10 in a single cast. Also, they can be found in all three schools to the south of Bald Knoll, but take care as the third school to the south is up on higher ground, and past many toads (stealth is needed to be used unless someone is killing them all). I recommend setting your home point at Bald Knoll, fishing all three schools (starting at the one closest to Bald Knoll), and then simply returning, as this saves a few minutes for each cycle of schools, since you don't have to use stealth to get away from the toads.
The older style are found in Cedarwood (grade 4), in one school, and one school only. It is located directly east of the aethereal gate (through the cave, over the bridge, down the hill, over the second bridge--there is a spear fishing spot down there, on the map, looks like a little island/peninsula.) These herrings are used for crafting such as alchemy and cooking. IIRC these cap at 8 per cast (again stupidly high, but that is due to being only found in one school in the entire game).
Happy gathering!

Edited by user Saturday, July 14, 2012 5:34:56 AM(UTC)
| Reason: Not specified