Magikarp (and some others?) require at least 400 candies to evolve. The obvious way to evolve a Magikarp is to catch 101 wild Magikarp (which would take me about 0.5 years).
Thus far, I’ve caught 1 (maybe 2) Magikarp and hatched 1. My current candy level is 13. And, I’m not sure why it is 13.
strategy for evolving Magikarp
1. Hatch as many eggs as possible, and hope for a Magikarp (that seemed to yield 10 candies).
2. And of course, catch as many in the wild as possible.
What else can I do to accelerate the evolution of my Magikarp?
The quickest way I have experience to catch Magikarp is to locate a Pokestop next to a body of water. With the combination of a Luremodule and an Incense, I have witnessed people “fishing” for Magikarp. I sat there and a Magikarp was spawning roughly every 2 minutes