Why are we so obsessed with isolating short "fish" upon whom we have very little data.

One can argue that fish one with his 57% hands played in 25 is a fish pre. But it is only 25 and that will include some ill judged "blind defence" and some pf limping. Here he is calling a raise so his range, though weak, is not as weak as normal. We also don't know that he is a spazz post flop with any pair yet.

"fish" number two is in his first hand and all we have are reads are that he posted and is playing a shorter stack. Posting in the CO is not uber terrible, and after 1 caller of an utg raise, there are a lot of hands it is worth calling with getting 3.25-1 and having decent position post flop. I'd like either more information than 1 street before deciding he's a fish, a bigger stack so that it's worth the gamble, or a better hand.