People are already making jokes. "Will the fish count towards attendance?" was one I saw. I think it's a nice idea. Not as much as having Flipper in a tank though.
As a fan of a team that has a no frills stadium (Dodgers), I usually cringe at **** like this. But I kind of like this idea. At least it has relevance to the team and area, which...actually makes it appealing to see in my opinion. As oppoed to a large baseball glove and coke bottle slide like they have in SF. And someone has GOT to kep a tab of all the weird things that happen in the aquarium during a tv broadcast.
I usually hate gimmicky stuff like this but I think it's kind of cool. My only fear is that the infielders might lose sight of the ground balls off the bat due to the aquarium background. Hopefully they check that out before they just go ahead about put it in, unlike what the builders did with the catwalks at Tropicana Field.