[egordo877]

You should raise on 4th, you don't mind it headsup and it looks like Fish4 will play with you. If anything, the bigger pot may tie-on players and encourage them to be a little looser on 5th.

I would raise once on 5th, you are not a huge dog even if he has the flush. If reraised I would grit my teeth and call down.

On 6th and the river you played it fine, not much you can do at that point.