The 6-foot-6 Steckel has scored 73 points in 398 games over eight NHL seasons with Washington, New Jersey and the Maple Leafs. He played for the Capitals and the AHL's Manchester Monarchs under Bruce Boudreau, now the Ducks' coach.
Steckel's consistent excellence on faceoffs and penalty killing should fill two areas of need for streaking Anaheim, which has the NHL's second-best record at 20-3-3 after winning five straight games.
"Adding David Steckel gives us another big body and depth up the middle," Ducks general manager Bob Murray said. "He comes highly recommended from Bruce. Faceoffs have been something of a concern for us the last few seasons. Steckel is a tremendous faceoff man and penalty killer, something that will really help our club."
Steckel was the Los Angeles Kings' first-round pick in 2001.
The Maple Leafs needed to clear a roster spot with Joffrey Lupul returning from a broken right arm, and Steckel had just one assist in 13 games this season. Toronto acquired Steckel from the Devils in October 2011.
Lasch played 19 games for the Ducks' AHL affiliate in Norfolk this season. The California native most recently played for Vaxjo in the Swedish Elite League.
After acquiring Steckel, the Ducks reassigned left wing Patrick Maroon to Norfolk. He has two goals in 11 games for Anaheim this season.
In Fasth's absence, Jonas Hiller has backstopped the Ducks to consecutive 2-1 victories at Minnesota and Dallas on the first two stops of their three-game road trip.
Anaheim has earned points in nine straight games heading into its road finale Saturday in St. Louis. The Ducks have a 13-point lead over Los Angeles and San Jose in the Pacific Division standings with 22 games left in the regular season, and they trail Chicago (22-2-3) by just four points with a game in hand for the NHL's best record.