Some things I've learned since moving to 100NL:

Fish lines:
1) the min-bet, min-bet, big- bet bluff line. I think they do this because when they min-bet and you don't raise they think that you can't have a strong hand so they put out a huge bet on the next street to try to force a fold.

2) the small bet with top pair. They seem to bet really small with top pair a lot of the time. Like less then half pot and do it on multiple streets. For a while I kept calling with my mid pair or whatever thinking that I only needed to be ahead a small % of the time to make a call correct. You're never ahead though. I think this is like the fish version of a thin value bet.

3) the flop raise with top pair. This happens way more than at midstakes games. It's often a minraise. Just make sure toy don't fold your TPGK hands too much.

There's more but I can't think of them right now. I'll add to this later.