The algae you're describing is most likely filamentous algae. This algae in high enough concentrations will cause dissolved oxygen issues which can lead to fish kills. With only about 100 fish in the pond, however, I wouldn't worry about it too much right now.
With larger fish populations comes less room for error, and it may be necessary at some point to intervene. This year in my pond, I'm going to stock tilapia to eat the algae. Others treat it chemically, but from the little experience and knowledge I have, it tends to be an expensive path of management. You could rake out the algae, but expect it to return in a few weeks.
I'm by no means an expert, but there are plenty of them here on the forum that should answer shortly.
