You still havn't answered what kind of cichlids you're keeping... if they're tropheus or Mbuna, then your options are pretty limited to anubias, and maybe java fern. Java fern can get very large, if you've ever seen a "mother plant" they can get downright huge, with 12" leaves and tangles of rhizome. If it's possible for you to establish the plant in one tank and them move it to the cichlid tank once it's started really growing, you might have better luck. Another grassy plant that tastes bad is crinium or onion plants. They have long strappy leaves that come in a variety of morphs from wide and straight to thin and curly, to ruffled leaves. I have mine in ceramic pots that I've covered in silicone and then covered in gravel. It won't help with the nibbling problem, but it helps keep them from getting uprooted.