Pokémon Go's Water Festival event brought with it the arrival of shiny Pokémon, specifically golden Magikarp and red Gyarados. But here's the kicker: unlike eyeballing a Magikarp's gender based on the color of its whiskers, you can't tell if a Magikarp you encounter in the overworld is shiny until you tap on it and initiate Pokémon catching mode.
Naturally, this has made some players wonder whether or not Niantic has a hidden mechanism for determining whether a Magikarp is shiny based on player data.
Pokémon Go shiny Magikarp odds: Is there a hidden mechanism to decide?
A player on the Silph Road reported on March 28 that they'd caught a shiny Magikarp on two consecutive days at 8:13 a.m. and 8:15 a.m. respectively, and wondered if there might be correlation between the time a Pokémon spawns and whether or not it's shiny.
As anyone who followed the similar discussion about special evolutionary items a few weeks ago will know, this particular hypothesis didn't bear much fruit, but it did spawn some interesting theories. One in particular, explained by Puella_Magi, hypothesized that there might be some correlation between the last eight digits of your trainer ID and the Pokémon's encounter — essentially, if they matched up, the Pokémon would be shiny and if not, it wouldn't.
Sadly, there are a few issues with this supposition. One is that if Niantic opted to do it this way, your chance of encountering a shiny Pokémon would always be 1 in 256, since there are only 256 discrete ways for your trainer ID and the encounter ID to end, and you'll only ever have 1. This would make Niantic unable to change the spawn rates for shiny Pokémon, meaning you'd never get a shiny event like the Valentine's Day one, which saw in increase in pink colored Pokémon and Fairy types.
Additionally, even if that was the way Niantic opted to implement shiny Pokémon, you'd have no way to check the encounter ID or your trainer ID prior to going into battle, so it's a moot point.
"On the off chance you were asking if there was a way to actually view your trainer ID and encounter ID," Puella_Magi wrote at the end of their explainer, "I really have no idea. Probably not."
Pokémon Go shiny Magikarp odds: Is there a way to increase your chances?
Yes, there is. Since Magikarp no longer hatches from eggs, your best option is to go to your nearest lake, river or other body of water to take advantage of the increased Magikarp spawns that you'll get from being in a water biome. Sure it's not as easy as it would be if you could just show up at a particular spawn point every morning for an easy shiny Magikarp, but nothing good ever comes easy. So you might as well take advantage of anything that can increase your Magikarp spawns.
Additionally, it'll still take you 400 candies to evolve that shiny Magikarp into a red Gyarados, so you should probably try to prolong the excitement of each Magikarp potentially being your first shiny for as long as you can.
More Pokémon Go guides, tips and tricks
If you're booting up the game for the first time in a while to get ready for Gen 2, be sure to check out Mic's guides on how to get stardust, how to determine how long it will take you to reach level 40, how to create new PokéStops, how to maximize your chances of catching Pokémon and how PokéStops distribute Pokémon eggs.