I wouldnt do anything either. The beak part of their nose is extremely resilient although it can sometimes deform permanently.
If it were serious I would net the fish out and drop some undiluted anti-fungal medication directly on the wound. Head down so none gets on gills and it should lightly stain the area. One or two drops directly on site is more effective than damaging biological filtration.
To sum up, I wouldnt worry and wouldnt feed till it gets better (its fat now) but those cichlids will disappear during the night sooner or later....