I wouldn't mess with the water either. Softening the water might help with breeding, but it's never been something that I've intentionally done, and my danios breed constantly as long as they are healthy and well fed. My danio choprai breed almost on a daily basis.
Egg layers don't get pregnant, the females get full of eggs. That fish looks maybe a bit overfed or bloated, just hold off on feeding for a few days and see if it looks better. They definitely eat their own eggs and fry, if you have a heavily planted tank you might get lucky and have some survivors.
I make egg traps to catch the eggs and then hatch them in a separate tank. It works great.