[uncleshady]

Preflop was a mistake, but fish make mistakes.

He was actually ahead of everyone but you on the flop, but you didnt raise PF either, so he didnt know he was way behind.

The turn gave him the best hand. Fish usually check this and try to come over the top later with it.

You figure you are safe and bet again. His plan is foiled when the the other guy stays in the hand and the board makes a straight possible.

or

He only called to keep you both in the pot.

and lets not forget, lets not forget...

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