Shortly after beginning the Moonglow Bay journey, players can start accepting requests from the town’s notice board as well as directly from citizens. Casper Braun is one such citizen. You’ll find him minding his own business at the beach nearby the protagonist’s home. After speaking to Casper, he’ll ask you to find him a Purple Tail. He claims Purple Tail is common in the area, but he’s actually referring to the name of the dish rather than the fish you’ll need to cook it.
The Steamed Purple Tail requires a single Slicing Tail. The Slicing Tail is a small fish that can be caught using the Spinner and Jig lures at any time of day. Because it’s small, you don’t have to use any bait for this catch. While there are multiple locations Casper tells you the fish hangs around, it can be caught from the comfort of Moonglow Bay’s own waters.
Head to either of the town’s fishing spots at the beach or on the docks and continue fishing with the Spinner lure until the Slicing Tail bites. With it in your possession, go home and select the Steamed Purple Tail recipe from the cooking menu.
Making the dish only requires washing, chopping, and baking. Grab the fish from the fridge and wash it at the sink. Move the left analog stick back and forth to keep the needle inside the blue bar until it is fully washed. Afterward, chopping is as simple as timing B button presses with the bars along the circle. Once the fish is chopped up, take it to the oven to bake it. Press B when the inner circle reaches the outer blue ring. The controller will vibrate to indicate the proper timing.
Return to Casper at the beach to hand him the Steamed Purple Tail and complete the request.