How can I complete "Omega: Packages For Ish"?

This is a known bug in Mass Effect 2, and as of the most recent patch/steam version, is still in effect. There is no current solution.

These are the possible paths to take when starting this mission for the first time. Bringing the package to Anto will allow the quest to properly close, but locks you into the rewards and responses from that decision - which you may not want.

From the wiki, these are your options:

If you bring the package to Ish, you can either:

• Give the packages to Ish for +50 experience, +4500 credits, and +5 Renegade points.
• Or convince Ish he's in over his head for +40 experience, +3375 credits, and no morality points; yet the mission remains open in the
  journal.

If you bring the package to Anto (one of Aria's bodyguards in the Afterlife Club) - which you can either do first or after convincing Ish to leave as described above - you can either:

• Give the package to Anto for +5 Paragon/Renegade points.

• Or extort money from Anto for +40 experience, +2250 credits, and +5 Paragon/Renegade points.

In either case, no one will hear from Ish ever again if the mission is turned in to Anto. Should you choose the middle option of "Take care of Ish", Shepard will simply suggest that Anto "clean up the mess" by killing Ish, which Anto does. And if Jacob is in the squad, he finds Shepard's choice to be harsh, though he still sees that Ish deserves such an end. If Miranda is in the squad, she'll say that "that's exactly how [she] expected Ish to go out".

Current Bioware Forum BUG thread: http://social.bioware.com/forum/1/topic/106/index/888625/5