So bloat is an odd thing... But the short answer is that it doesn't matter, ie the fish will always have it in them but stress causes there immune system to not be able to handle it.
For better info I am ripping this off the clout treatment a few posts down, posted by Fish Phenom:
"Malawi Bloat is believed to be caused by a flagellate (a unicellular animal, a protozoan). This flagellate occurs in the intestines of all Malawi cichlids but normally causes no harm since the fish's immune system can cope with it. However, in a stressful situation such a balance may disappear and the fish may lose its resistance against an outbreak of a flagellate "attack". This often leads to bloat."
Fish are very good at fighting off disease, but when exposed to stressful conditions over a lengthy periods of time their immune systems weaken, thereby exposing them to the possibility of contracting various diseases. Under "stress" the organism multiplies causing considerable localised damage. Once severe enough, the intestinal lining is penetrated and the organism enters the blood causing systemic and organ infections. In large numbers they can block the intestinal tract of a fish creating the"bloat"effect.
Some stressors:
1. Low oxygen (O2) levels
2. High nitrite (NO2) levels
3. High nitrate (NO3) levels
4. High ammonia levels (NH3)
5. High or low temperature levels
6. Water pH
7. Lighting
8. Rough handling fish
9. Overcrowding
10. Not enough shelter
11. Harassment
12. Excessive salt
13. Improper diet (specifically herbivores)
What one should remember, is that the parasitical outbreak is brought upon by any number of stressors (some listed above), many times in conjunction with one another. Therefore, sometimes the best way to treat a disease is to prevent it from ever happening. A clean non-stressful environment will breed colorful, thriving cichlids.