Those "whiskers" are ventral fins. Do you have pictures of the ventral fin missing? It depends on which part it appeared missing or nipped. Was it nipped? How long has it been that way?
they are also really sensitive so if your gourami keeps getting its pelvifins nipped at (i'm guessing gourami on gourami aggression) then it would be best to rearrange your stock if you don't want to put your gourami through the pain.
It should grow back, from my experience anyway. I have a pearl gourami in one tank and 2 honeys in another tank and both have had their pelvic fins nipped at one time due to a betta with a serious attitude problem. Once the Betta was removed they grew back fine, almost as if they were never nipped.