How can i get rid of this Algae in my fishtank?

Get a Siamese Algae eater. They will eat the algae off of your plants and other decorative surfaces and then don't harm the plants leaves. do a little research first: make sure the store is not selling you a Chinese algae eater (a very common fish at pet stores) or a flying Fox (looks similar to a siamese algea eater). Good luck!