Where to catch Qwilfish

In Paldea (Scarlet & Violet)

• East Paldean Sea — Walk
• North Paldean Sea — Walk
• South Paldean Sea — Walk
• West Paldean Sea — Walk

In Blueberry Academy (Scarlet & Violet – The Indigo Disk)

• Polar Biome — Walk

In Johto & Kanto (Gold, Silver & Crystal)

• Route 12 — Super Rod
• Route 13 — Super Rod
• Route 32 — Good Rod, Old Rod, Super Rod

Qwilfish — full Pokédex entry