Cool.
And once it's programmed, it's portable to your other screensavers.
BTW, even with two screens to work with, I usually have fewer than the 7-fish maximum at any one time. Don't like it feeling crowded or too busy. So, I'm thankful for the lionfish, that moves slowly and looks so different from the others. For the same reason, I'm eagerly anticipating the crustaceans and anemone. I also like somebody's idea about an eel or other creature that is mostly in hiding, but just occasionally darts from one bit of cover to another -- a little bit of mystery to keep us from getting jaded.
When you add personalities to the other fish, some of them would practically jump out of their skins whenever the lurker-in-darkness sprinted to its next hidey-hole.
As for the existing fish, and having had aquaria before, I keep expecting them to occasionally turn and nudge the front glass, but they never do. That, along with the mouth and gill movements will certainly bump up the realism quotient on an already very convincing little world.