Can you get a shiny magikarp instead of a shiny gyarados in Pokemon heart gold?

Question

I got a shiny magikarp in the lake of rage and my friend says you can't get one instead of a gyarados. Is it possible, or was it a wild shiny Pokemon?

Answer 1

It was simply a random wild shiny. It is not impossible to find a shiny other then the Gyarados at Lake of Rage. The Gyarados was more of a free shiny as it will always be shiny vs your Magikarp which only had a 1/8192 chance to be shiny. Congrats on your lucky find ^.^

Answer 2

It was a wild shiny Pokemon. From Bulbapedia:
"In Pokémon Gold, Silver, Crystal, HeartGold and SoulSilver, the red Gyarados is found in the Lake of Rage. The player has one chance to catch it and the incident triggers the battle against Team Rocket in the Team Rocket HQ in Mahogany Town. When captured or defeated, the red Gyarados drops a Red Scale. "