Question about tank reflection

I have a 55 gallon tank set up with 2 Clownfish, 10 hermit crabs, and 5 snails. Currently my clownfish sit on one side of the tank just staring at their relections. Occassionally they will swim around the tank, but they mostly just stay to that one side. Is this normal behavior? Is there something I can do to eliminate the reflection in an effort to get them to use the whole tank?

thanks,
jeff