Here's how, but you have to have a lot of patience...
Receive the Old Rod from the Fishing Guru in Viridian City. Make sure you have plenty of Pokeballs in your Inventory, so if you do encounter a Shiny Magikarp, you'll be ready. Also make sure that your Old Rod is registered for easy use.
Go to any area of water and fish. If the Magikarp you encounter is a golden color, congratulations, you found a Shiny! If not, keep Running.
The chances of encountering a Shiny Pokemon is 1 in 8192, so if you're real desperate to get a Shiny Magikarp, you've gotta have patience.
In my main game, FireRed, I have 2 Shinies, a Level 100 Crobat (evolved from a Shiny Golbat), and a Shiny Venomoth, caught in the Safari Zone. It was completely unexpected, but remember, it ALL depends on luck.
Happy Shiny Hunting!
~Katie
Chat with our AI personalities
It depends on luck. when catching a magikarp, you have a 1/8000 chance of shiny.
There is no way to get a Shiny Magikarp 100% of the time.
A golden Margikarp is a shiny margikarp, and as with other shiny Pokemon, there is only a 1/1892 chance of getting a Shiny(golden) magikarp. Breeding a Shiny Gyarados or a Shiny margikarp with another shiny Pokemon THAT CAN BREED WITH GYARADOS/MARGIKARP may have a higher chance of breeding a shiny magikarp. You can also trade the shiny gyarados from Pokemon Gold, Silver, and Crystal version.
I am lead to believe Magikarp evolves at level twenty.
The Gold Magikarp is a shiny Magikarp. It evolves into a red Gyarados. There is a 1 in 8912 chance that the Pokemon you encounter is shiny. This can be reduced to 1 in 2048 chance by using the Masuda method. This is basically when you breed a Magikarp with a foreign Ditto. The egg has a 1 in 2048 chance of being shiny.