@philipabb For me I usually spot the fish in the first 20-30 hands, not by one big hand but by small patterns.
The first sign is limping too much, especially limping and then calling a raise. Good players rarely do that.
Second is playing too many hands and showing down with weak hands like bottom pair or bad kicker. If someone shows down J-4 offsuit from early position, I know who to target.
Third is bet sizing. Fish usually bet too small with strong hands and too big when bluffing, or they just min-bet all the time. It's very easy to read.
And to be honest, yes, I have been the fish many times. Especially when I was tilted or tired, I started limping, calling too much, and chasing draws. That moment when I realize I'm the fish is when I know I need to quit the session.
How about you, do you spot them fast or does it take you a while?