Sea Route 41 — Pokémon Crystal
Every wild Pokémon here, by encounter method.
Sea Route 41 lists 7 Pokémon across 4 encounter methods (surf, old rod, good rod, super rod), between level 10 and 40. One of them is on no other route's wild tables in this guide: Mantine.
Sea Route 41 in the official games
The original game's table for this area: