One of the most recognised markets in Siem Reap. It's worth the visit for the atmosphere. You can find literally everything here - from souvenirs to traditional Cambodian dishes. It is no exception to see live fish in tanks. Don't skip prahok, which is a salted and fermented fish paste.
Daily: 8 am - 6 pm
Wikipedia https://en.wikipedia.org/wiki/Psah_Chas
Address (Unnamed Road), Cambodia
Coordinates 13°21'13.927" N 103°51'18.652" E