>When I do 'repo form myrpt' it print nicely, no spaces between lines.
>However when I 'repo form myrpt to file fish.txt', it comes out double spaced in fish.txt. Is this normal?

Along with what Ed said, you also have to make sure that ALL the fields in your detail band are exactly the same height and are in the same place vertically. Make sure there is no extra space above or below the field in the band.