In the newly-released mobile game Pokémon Magikarp Jump, the Magikarp you raise can actually die. Your Magikarp can come across a shiny object in the water, and the game will ask you if you want to go for it. Although it could possibly be Diamonds, a form of in-game currency, it could be a fishhook and you could be sending your poor Magikarp out to die. You may also be asked me if you want to make your Magikarp get a Berry in a tree. But this could lead to a Pidgeotto swooping in and taking your Magikarp away for good.
Source: Kotaku