This quest is a pain but is easily doable. One of the quests in Vashj'ir, Underlight Canyon.

Quest: Coldlights Out
What to do: Wear a lure hat to attract fish
Whats the issue for Mboxers: Attraction of 30 fish for each toon
What to do: Look for these fish hanging out at the end of of the coral that look like tree branches, they are very small fish, find a small version of this corral and hold a position with each toon at a spawn point around that coral. One at a time take one toon to add more fish by swimming the ends of the coral not camped.