Master Hunter 8: Catch 3 Small Fish Without Using A Fishing Rod.
You will need to complete Chapter 1 as a prerequisite, and the rewards are 100 Health XP and $15.
In this guide, you will find a way to complete this challenge in Red Dead Redemption 2.
The first thing you have to do is go to any lake or river. When you see fish, shoot them with your pistol or rifle, and you’ll be able to pick them up after that.