I have noticed a distinct lack of frogs eggs in my pond over the last 6 months, this image is of my Villarsia exaltata full of eggs over the summer. This particular plant was the favoured plant by the frogs for laying there eggs. It seems to have a nice branching height above the water to protect the spawn cluster. 

I was also told that having fish in your pond will stop frogs entering it to breed…I have always had at least two gold fish in my pond that haven’t seemed to stop the frogs before, however maybe now they are bigger and are eating the eggs, who knows?…it seems to be a fine balance, I am going to add some more reed type plants and hope for the best. Below is a healthy pond where the fish are kept in the lower section, leaving this upper pond for the frogs.