Probably a bad combo, Mayans are nasty. Don't rule out all cichlids, there are plenty that make good tankmates for gar; discus, peacock bass, bay snook, etc, just pick more peaceful species.
I'm guessing that it's either one of those "gars" that's really just a Characin or Belonid, or it's a Florida gar under a trade name.
Either way, I think that the Gar forum needs something similar to the "Marketplace Rules" that appear above threads in the "Buy & Sell" forum except the "rules" would detail what qualifies as a true gar since no one ever seems to read the stickies...
If the marble gar is in fact a Florida gar, then a bigger aquarium will be needed in order to house it for life, and true gars and aggressive cichlids make a very poor combination in most cases for multiple reasons that have been previously stated in other threads and stickies.
If the marble "gar" is in fact something that's not a true gar e.g. a Characin or Belonid, then it will most likely be bullied to death by the cichlid, especially if there is a big difference in size with the cichlid being the larger of the two fishes.
Can someone point me to these "other threads?" I suck at using the search here or don't know how it works...as I can never find pages/threads people say exist...my searches never give me what I am looking for. I have a beautiful gar and a beautiful Mayan and want to read up on this. I was hopeful about the 2 being friends...lol...but, no longer. Thanks.