"I'm excited and ready for the opportunity, and I can't wait to get out there," said Marisnick, who is wearing No. 6.
Marisnick played in only 54 career games with the Marlins, hitting .178 with one homer, five RBIs and eight steals. He's a career .279 hitter in the Minors, including .277 with 10 homers, 24 steals and 40 RBIs this year at Triple-A New Orleans.
"I need to keep doing what I've been doing throughout my career," he said. "I've made adjustments, and once I've adjusted, I've been able to do my thing, and I feel like I'm ready to go."
Marisnick, whose 6-foot-4 frame bursts with athleticism, should have no trouble covering a lot of ground in the outfield or creating havoc on the bases. Marisnick has overcome some injuries, too, getting hit by a pitch on his left hand and missing all of Spring Training and the first month of the 2013 season, and then tearing the meniscus in his knee late last year.
Astros first-base coach Tarrick Brock, who works with the team's outfielders, was familiar with Marisnick from Brock's time as a coach in the Marlins' system.
"It's a big, tall guy who's very athletic," Brock said. "The biggest thing when I was over there was his maturation process as a hitter. He has the tools that play here. With the outfield they had [in Florida], it was pretty hard to break in over there. He's a guy you just can't have on the bench, either. This will be a good opportunity for him to come here and play, and show what he can do at the Major League level."
Brian McTaggart is a reporter for MLB.com and writes an MLBlog, Tag's Lines. Follow @brianmctaggart on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.