Catch or defeat water-type Pals
Common Pal Fluid sources include:
Pengullet
Teafant
Fuack
Celaray
Kelpsea
Surfent
Relaxaurus
Use a Water-type Pal in your party to help farm them faster
Check beaches, rivers, lakes, and coastal areas for water-type Pals
Loot dropped items from defeated water-type Pals
Buy Pal Fluids from merchants if available in your world