Best Fish is a culinary ingredient in Resident Evil Village, required for the Sarmale de Peste dish, which greatly increases your movement speed.
Where to find a pond with the best fish
To find the best fish, you will need to defeat Moro and get the handle. Once you have it, head to the central location where the Duke is located and head west until you reach a raised bridge (you might have found it earlier).
Use the crank and cross the bridge, then get on the boat and head down the river (south) until you can dock again. When you’re back on the ground, don’t go into the cave (although you can find an ancient coin and other valuables there), but keep heading south until you reach a pond where the best fish lives.
To get the required ingredient, shoot her or stab her. Then the best fish and 6 units of ordinary fish must be taken to the Duke in order to prepare Sarmale de Peste.
Best Fish is one of the three rarest ingredients in the Village that can only be obtained once, just like Quality Meat and Juicy Game. So be careful not to accidentally sell them.
A source: culturedvultures.com