Though this place is much smaller than the Nong Khai aquarium and lacking any Mekong catfish (þlah bèuk) on our last visit, it's still mildly enjoyable to see the various species from the Mekong River. It's 6km west of town along Hwy 22.
Admission also includes Chakri Memorial Hall in a nearby building. Most of the displays are about King Rama IX and the province's various ethnic groups, but unless you can read Thai it's probably not worth your time.
Sŏrng·tăa·ou to Na Kae pass in front of the aquarium (20B, 20 minutes).