The Fishing Guru is an NPC in Pokémon Crystal that asks you to show him the biggest Magikarp he’s ever seen. In exchange, he’ll give you an Elixer.
The Fishing Guru is in a house near the Lake of Rage coastline. It’s southeast of where you find the Red Gyarados during the main story. To obtain an Elixer, you must surpass the current record set by a 3’6” Magikarp. You can attempt this side-quest as many times as you’d like.
Even after winning once, you can keep bringing in more Magikarps to attempt to break your own record. Each time you break it, you get another Elixer.
You can check the latest record on the signpost next to the Fishing Guru’s house.
The Fishing Guru won’t measure any of your Magikarp until you’ve taken care of the Team Rocket hideout in Mahogany Town.
Here’s what you need to do to drive them away:
- Defeat or catch the Red Gyarados in the Lake of Rage.
- Talk to Lance back on the shore to team up against Team Rocket.
- Raid Team Rocket’s hideout beneath the Souvenir Shop in Mahogany Town.
- Defeat the Rocket Executives and deactivate the radio signal machine by defeating the Voltorbs used to power it.
Only then will the Fishing Guru stop worrying about the environment and return to looking for the biggest Magikarp.
Finding the Fishing Guru at the Lake of Rage
Using Fly to reach the Lake of Rage should leave you next to the Fishing Guru’s house.
You can also get there on foot if Fly isn’t an option.
Start by going northward from Mahogany Town and into Route 43.
Stick to the right when the road splits.
Go through the building to the northeast and keep to the right afterward.
Follow the road north, past some trainers, until you enter the Lake of Rage area.
You’ll find the Fishing Guru’s house to the right after the “Lake of Rage” title card disappears.
Talk to him inside to hear about how the Magikarp have returned to the Lake of Rage and how he wants you to help him find the biggest Magikarp ever.
How To Catch the Largest Magikarp
The easiest way to catch a large Magikarp is to fish somewhere other than the Lake of Rage.
Game Freak intended to make the Magikarp in the lake larger than average. Regrettably, a bug made them smaller instead.
This bug extends to Routes 43 and 44.
But here’s the good news: you should be able to hook a Magikarp with the Old Rod almost anywhere you find water.
Tip: Using the Old Rod usually limits the Pokémon variety, attracting more Magikarp.
You can also try to catch Magikarp by surfing inside the Dark Cave, east of Violet City. Remember to bring a Pokémon that knows Flash to light up the cave. Only Magikarp inhabit the waters inside the cave, so you’ll catch many of them fast.
There’s no real way to know what a Magikarp’s length will be until you show it to the Fishing Guru. You just need to catch a bunch of Magikarp and hope at least one breaks a record.
The minimum length you’ll need to break the initial record is 3’7’’
Repeating the Magikarp Hunt
You can keep showing more Magikarp to the Fishing Guru after breaking the record for the first time. Every time you break the record, you’ll get another Elixer.
Tip: You can check out the latest record on the signpost next to the Fishing Guru’s house.
The original record is just 3’6’’. If you break it by a little bit (e.g., 3’7’’), you should keep trying to get more Elixers.
However, remember that Magikarp’s max length is only 5’3’’.
The closer you get to that number, the harder it is to break the record until it becomes impossible.
Can I Show a Traded Magikarp to the Fishing Guru?
The length of a Magikarp is determined by a complex formula using your Trainer ID and the individual Pokémon’s DVs (Deter Values).
Note that it’s your own Trainer ID that matters, rather than the Magikarp’s original trainer.
For this reason, a Magikarp’s length will change when traded into another game of Pokémon Gold, Silver, or Crystal.
Therefore you can’t rely on a traded Magikarp to break the record. It’ll have the same chances as any other Magikarp.