Inside Social Games has just released the Top 25 Facebook Games for December 2009, and here’s the list:

Here’s what we’re seeing:

• Zynga’s FarmVille continued its growth by more than 6 million monthly active users to nearly 70 million. However, this is only a little more than half of what it earned last month. Meanwhile, YoVille lost more than 500,000 users and going from from #6 to #8. Roller Coaster Kingdom stayed at #11 with close to 15.5 million MAUs.
• CrowdStar’s Happy Aquarium continued to grow, holding on to the #4 spot, despite the number of Zynga titles around it. The virtual aquarium game is followed on the list by Playfish’s Pet Society at #5. CrowdStar’s second title on the list, Happy Pets, came in at #22 with almost 5.5 million users.
• After weeks on our Top Gaining Charts, FishVille has made a splash at #6 with more than 21 million users.
• MindJolt Games lost 1.1 million MAU to land at #12.
• And finally, long after its initial release, Mobsters 2: Vendetta from Playdom has made its way into the charts with roughly 5.3 million MAUs, followed by another newcomer, My Fishbowl from 6 waves at #24 with a monthly user count just shy of 5 million.

Fore more, check out the full story on ISG.