Živá Voda Aquarium, Czech Republi

In Modrá, by the folk skansen and near the impressive basilica and pilgrimage site of Velehrad, you can visit Živá Voda.  It's a cool place with an herb garden, outdoor representations of the different environments in the Czech Republic, a pond you can wade in (complete with frogs and fish), interactive exhibits good for kids, and the most awesome thing:  a glass tunnel under the freshwater pond where you can see giant fish from below.  The biggest fish there is a Beluga (European Sturgeon) measuring 2 meters!  It's apparently the largest freshwater fish.  You can also watch a lot of huge carp and other cool fish.  Amazing to see them from that close.

   It's hard to show the true size, but here's a hint--with one of the smaller fish.