Usually healthy fish should be able to fight off bloat when in optimal conditions, but bloat is contagious (though there are varying opinions on this). There have been stories of fish becoming ill repeatedly, having to be treated again and again. Fish may mouth the feces of infected fish, giving the other fish the bloat disease.
I'm not very good with bloat as I never really had the disease, so it is best listen to people with first-hand experience with bloat.