Although it's looking a little shabby these days, this large aquarium offers a fairly interesting collection of freshwater and ocean-dwelling fish from Thailand and beyond. The highlight is the 'Big Tank', which features Mekong River species, including giant Mekong catfish, and has a walk-through tunnel. There's a scuba feeding performance daily at 2pm and also at 11am on Saturday, Sunday and public holidays. The aquarium is 8km out of town. Expect to pay 200-300B for a return tuk-tuk, including waiting time.
Nong Khai Aquarium