I've heard that you don't really have to baffle a filter intake, as the fish should be able to free itself if healthy and as long as the filter isn't too large for the tank.
I left mine un-baffled for all of one day, then I looked up and noticed that my fish likes to stick himself on the intake because he likes the way it feels, or whatever (he gave me this adorable LOOK MOMMY LOOK LOOK!!!!! face as he attached and detached himself). He could free himself, but I was worried he'd damage his fins.
It's up to you whether you want to wait and see what happens or go ahead and sponge over it....
It looks like for that one, what I'd do, is just tie/rubberband some filter sponge around that bottom part. Of course you're going to have to make sure your fishy can't get stuck in it. The filter will still suck through the foam. I got some Fluval filter sponge for $5 at Petsmart and when Mr. Fish lets some food flakes dribble out of his mouth they get sucked right in.
OR if you want to be really particular, you can get a rectangular piece of filter sponge long enough for you to be able to cut a slit to wrap the whole piece around the bottom (eliminating the string/rubberband/whatever). The Fluval sponges I had would have worked well for that. Basically, you want to cut the sponge down the middle of the width and through to the other side, but leave some hanging on the side edges so that it wraps around. I hope that makes sense! Basically a top/bottomless cylinder.