water hyssop in a pond

Hi, I'm constructing a pond as part of an upcoming garden (quite a large job in full, and is slightly over my head), and am curious about the water hyssop as a native pond plant. I would like to include the plant in the pond, but have two concerns :
1 - does anyone know how easily it could dominate the pond, or to what extent fish could stifle/complicate its growth?
2 - what is the possibility of the plant getting out of the (lined, not natural) pond and onto the 'yard' ?

any input at all would be appreciated!!