From Nookipedia, the Animal Crossing wiki
This is a list of the recipes in Animal Crossing: New Horizons that may be obtained from Pascal. When the player finds a Scallop while diving, Pascal may appear and ask if he can have it. If the player gives him the Scallop, he may reward them with a Mermaid DIY recipe (other possible rewards are a piece of mermaid-themed clothing or a Pearl).
Recipes in Animal Crossing: New Horizons
|Includes data sourced from this Item Spreadsheet, compiled by 6480, noizhub, Ricky, chaiinchomp, saberslime, robotic_scarab, mollumisc, sunmarsh, kyrokey, obstinateRixatrix, jackiwi, Zalex, SuperHamster, kait, hyuum, Azarro, Czarcasm, cinnamon_swirlix, astronomyfortwo, Welcius, glowtopia, BriKun, Alyrei, dodocodes.com, StevieCoops, sneeze, Shiny190, TwistedPeach, LavaToaster, capstone, vmario, rocklamp, Alexis, Aeon, and PanchamBro.