Riga Zoo has a small aquarium with a fairly big selection of small freshwater fish (no saltwater fish or big freshwater fish), of which the majority are pet shop species, though a couple of semi-rarities can also be seen (reed tetra, reedfish, Nile puffer). The tanks are also pet shop-sized, though the zoo is starting to combine some of them to make for bigger displays.
This picture shows the main corridor in which the majority of tanks are located.