1) The Skewered Fish is obtained after fully completing the quest Shards of a Broken Moon by talking to Nilavarna and getting the achievement "Amati's Echo".
2) The Jaracals are on the surface of Marapur. Before entering the Asura Citadel where the quest takes place, you can find them roaming close to the entrance.
3) It's not a guaranteed tame, I've failed a lot of times to tame a Jaracal, but in none of them the item break, so you just need to have some patience.