Eel Hunting is a Mycroft Case in Sherlock Holmes Chapter One. This walkthrough will guide you through the Eel Hunting side quest.
Starting Borough: Scaladio
Starting Location: Cordona Chronicle (newspaper building)
Quest Giver: Ms. Sertel (Editor-in-Chief at Cordona Newspaper)
Requirement: Finished Main Case “A Gilded Cage”
Reward: 
Catch of the Day (missable), 20 Money
Case Info: The Eels are a gang of smugglers operating between Cordona and Italy. Working with local fishermen under the legal name ‘Cordona Fish Company’, they stuff the fish with heisted gold to be covertly transported to Italy right under the nose of the British authorities.
Starting Location: Eel Hunting
Eel Hunting case starts in Borough: Scaladio, Place: Cordona Chronicle (newspaper building).
It’s only available after Main Case “A Gilded Cage“. Inside the building, talk to the woman behind the desk in the lobby. When she asks if you’re interested, say “Yes, I am” to accept the quest.
Solution – Correct Warehouse Location
Upon starting the quest, all 3 warehouses get marked on your map, they are in Silverton district. Warehouse No. 2 in the middle is the correct one!
This is effectively a one-step quest, because you can head straight to the correct warehouse without doing any of the objectives at all. No need to go through the clue gathering or putting on disguises or whatever, it’s unnecessary. The door to the warehouse is unlocked from the start. See the location below:
Inside, you will get attacked by some enemies. It doesn’t matter if you kill or arrest them. After defeating them by any means, a single enemy in heavy armor with a shotgun will spawn, which is our target “Friedrich Panzer”.
Missable Trophy: Catch of the Day – this is earned by entering the correct warehouse (Warehouse No. 2). It doesn’t matter if you kill or arrest Friedrich Panzer. Return to the quest giver afterward and the trophy will unlock. Going to the wrong warehouse would still complete the quest but wouldn’t unlock the trophy.
A very short and easy quest indeed. After returning to Ms. Sertel at the Cordona Chronicle, you can pick the dialogue “I’ll take the case” to start the follow-up quest “The Missing Shopkeeper”. This is available right away, no additional story progress is needed.
This finishes the Eel Hunting Cordona Story case in Sherlock Holmes Chapter One.
For all other Cases, view the full Sherlock Holmes Chapter One Walkthrough.
Definitely a super glitched one. I tried many times, restarting over the whole quest, restring ps5 etc and will pop. I am going in warehouse #2 and it is the correct target. I killed and captured both will not pop it after I handed it in.
Correction meant will not pop
It finally popped after 5 tries and restarting the ps5 and game twice. So if this happens just keep doing it over and over I guess which is super annoying.