This week, Zynga revealed it’s planning to sunset both Treasure Isle and FishVille, alerting players yesterday that the games will be shut down by Dec. 5. What’s interesting about the company’s decision to sunset these games now is that they both have more than 50,000 DAU, showcasing at least some basic parameters for what Zynga considers a successful game.

This follows CEO Mark Pincus’s revelation last week that Zynga was planning to sunset 13 underperforming games. At the time, Pincus didn’t go into detail about which games would be affected and company spokespeople declined to tell us any further information. Both of these games are older Zynga titles, having been on Facebook for several years: FishVille launched in November 2009 and Treasure Isle in April 2010.

Much like other Zynga titles, both FishVille and Treasure Isle saw large initial numbers when Zynga turned its cross-promotion on, with traffic falling off over an extended period of time. At their peaks, both games saw traffic reaching near 7.5 million daily active users (the best measure of a title’s core audience). While that’s an impressive milestone to hit these days on Facebook, it wasn’t as monumental back in early 2010; by comparison, FarmVille had over 30 million DAU during the same timeframe.

FishVille currently has 730,000 MAU and 70,000 DAU. 70,000 DAU in a nearly 3-year-old game is respectable, but it’s less than 1 percent of the game’s high point of 7.45 million DAU. Likewise, the game’s percentage of DAU over MAU is currently holding at 9.59, which is underwhelming when you realize a game needs 15 percent to be considered healthy.

Treasure Isle, meanwhile, has 90,000 DAU and 540,000 MAU. Again, this is significantly down from the game’s April 2010 high point of 7.4 million DAU. As opposed to FishVille, though, Treasure Isle’s DAU/MAU rate could still be considered healthy as it’s holding steady at 16.69 percent.