For some reason fullscreen-mode didn't zoom for me, but that's possibly something with my browser...
Moving around corners at some points wasn't completely smooth (as in; I had to move another pixel or so, to fit into the side pipe), but not too badly.
It seemed one could select which one of the fishes would be flushed, but maybe I'm imagining things.
Very nice puzzles with increasing number of mechanics. Good thing one could get more than one patch for the damaged pipe bits, otherwise there would have been some unnecessary extra backtracking needed... :)