I never had a bloat issue with mine, and have raised hundreds, but I do feed a high spirulina/vegetarian based diet.
In nature the main components of their diet seems to be algae and detritus, yet I don't think its the protein that causes bloat, but its the lack of fibrous material in many high protein aquarium foods.
I believe algae fiber helps to purge the gut, thus preventing an excessive build up of bacteria that cause bloat.
And believe this is the case with many omnivorous Central and North American cichlids, I have watched Jack Dempseys in nature spend more time chewing algae and detritous (such as fallen leaves) than hunting.
I also believe stress from being kept in close quarters with high nitrate to be a main cause of stress, leading to bloat.