FROM A FISHERMAN. Who wants you to catch a magikarp and trade it to him for the old rod
Literally anywhere you see water. Use a fishing rod to catch one. There all over the place! XD -Chii
By fishing or surfing in the whirl island caves
You can catch it on route 133 and 134 with a rod.
catch a horsea evolve it into seadra give it a dragon scale and trade it
you can catch spinarak in route 30
Route 133.
Horsea can be found in either Whirl Islands or Seafoam Islands.
Shiny Pokemon appear completely at random, although you could hack the game with an Action Replay (not recommended.)
you need to catch a gold magikarp(shiny) by fishing or breeding then level it to 20. Or you can catch a red gyarados(shiny) by random. The chance to have it red are i in about 8000
that's a stupid question
in the lake of rage you kan have him in shiny or you catch a magikarp and train him to lv. 20
You can get Horsea in Dark Cave or Whirl Islands. You'll need to Surf on water to get it.
In HeartGold or SoulSilver: Catch a wild Seadra, Dratini, Dragonite, Horsea, Dragonair, or Kingra holding the item. Or successfully find and catch a Horsea in the Winner's Path PokeWalker route. In Diamond, Pearl, and Platinum: Catch a wild Dratini, Dragonair, Seadra, or Horsea holding the item. In FireRed and LeafGreen: Find one on the Water Path. In Ruby, Sapphire, and Emerald: Catch a wild Horsea or Bagon holding the item.
You either trade from soul silver or heart gold, use a action replay to make encounters shiny, catch a shiny magikarp legit(which might take a while)
That would be a shiny charizard. You would have to get a shiny charmander as a starter, since there is no way to actually catch a charmander. A shiny Charmander is gold.
you can catch horsea in ocean current with fishing.