Depends on what algae it is. If its the stringy kind, the little fry might swim into it, but are unable to get back out. I give them more the green water to eat than algae itself - a cup full of green water contains so much food for them, its amazing! Tiny little particles are in it, that you can't even see, but its very nutricious for them. I also scrape a bit algae off of the tank walls and squish it either between my fingers or desolve it a bit in a little water, so its not actually algae anymore, its more like a watery paste....

Oh, and how to get rid of the algae without hurting the fry - try an eye dropper of some kind, or even a turkey baster used carefully. Suction out the algae, but watch out for the little fish. They can get sucked in as well...