The hobbits are celebrating the Lithe Festival. To aid them in their celebration, the Dwarves of Thorin's Hall are letting you catch and bring them fish.
NOTE: This quest will be removed from your quest log when the current festival ends.
'We dwarves have the greatest fish in all of Eriador. The river that runs through this great hall makes them powerful swimmers, which means lots of meat.
'You won't find a finer fish anywhere. I suppose we can be civil and share some of ours for the Lithe Festival in the Shire, but you've got to catch them yourself.'
Fish can be caught in the river running through Thorin's Hall.
Láfi has given you some time to catch fish for the Lithe Festival.