Where to catch Staryu

In Hoenn (Ruby, Sapphire & Emerald)

• Lilycove City — Super Rod, Walk

In Johto & Kanto (Gold, Silver & Crystal)

• Cerulean City — Super Rod
• Cherrygrove City — Good Rod, Super Rod, Walk
• Cianwood City — Good Rod, Super Rod
• Olivine City — Good Rod, Super Rod
• Route 34 — Good Rod, Super Rod
• Sea Route 19 — Good Rod, Super Rod
• Sea Route 40 — Good Rod, Super Rod
• Union Cave — Super Rod

In Kanto (Red, Blue & Yellow)

• Cinnabar Island — Super Rod, Walk
• Pallet Town — Super Rod
• Sea Route 19 — Super Rod
• Sea Route 20 — Super Rod
• Sea Route 21 — Super Rod
• Seafoam Islands — Super Rod, Surf

Staryu — full Pokédex entry