They definitely haven't been removed outright, because I still have a half dozen or so sitting in my bank.  There are also some duty officer missions attached to the science speciality for breeding tribbles (although you have to have certain specific tribbles to start the missions).  I suspect you can also still find some on the exchange for 1cr, or otherwise dirt cheap, although I haven't looked there in months.

As to where they drop in-game, if anywhere, though, I honestly don't know anymore.  It's been forever since I've gotten one as a drop.  I think it would have been fairly soon after launch when I was still playing episodes regularly.  If you have zero luck and simply want a tribble, let me know and I'll mail you a random one in-game that you can then reproduce at will.  

I leave them in the bank, and keep food in my inventory, for obvious reasons (you wind up logging in to a bag that has no food and two dozen tribbles in it).  As a lifer inventory space is never a problem.

Originally posted by ktanner3
I recently decided to come back and give the game another try. I played this game back in release and lasted for a couple of months before moving on. One of the things I used to like about this game was the tribbles you could collect and breed. Were those removed from the game because I haven't found any yet. 

Be careful to keep them away from the cannibal tribble if you found one :D

Took me until Lt 13 or so.  Wasn't sure where it came from, but I think it was one of the Klingon Front missions - I'm up to "Task Force Hippocrates" now so it musta been before that.  Not a lockbox, because I've never opened any.

Once you have a tribble, of course, getting more is not really a problem :-)