Cosmocaixa is a science museum located at the top of Barcelona. It cost 3€ and every first sunday of the month is free (I go there every first sunday ).
It's a museum but with many animals. The amazon forest contains anacondas, leaf-cutter ants, arapaimas, pacus, arowamas, brazilian teals, poison dart frogs, emerald boa, red-footed tortoise, hoco, brazilian dwarf caiman, mata-mata turtle and about 4 bird species that fly around the visitors inside the forest. In front the forest exhibit there are many small terrariums and aquariums with some fishes, reptiles and invertebrates (nautilus, sea-horses, clow fishes, Australian Blue-Tongued Skink, Periophtalmus koelreuteri, lungfish, hermit crabs, ...).
There are also an activity called "Toca, Toca!" where you can touch different animals....