Good question Rick,
Perhaps it's the same reason why humans have different issues, genetics? For example, the American Indian population can be adversely affected by alcohol, the black population has the potential of Sickle Cell Anemia, and the Jewish population can suffer from Tay-Sachs. Other populations are prone to heart ailments and high cholesterol…etc.. The big one is life expectancy; some populations of people live a very long time, into their 90s, while others do not. Is it only genetics, is it life style – i.e. healthy living, is it food based who knows.
Health issues can also be based on smaller groups such as families. In my own family, with a heavy Italian influence, the male members are prone to dementia and Alzheimer’s. Is it based on one person passing the gene down the line or is it based on ancestry?
Obviously this theory isn’t scientific and I’m aware that not all people in a single race are affected the same, as in your H. beani example, but there is a lot of information on the web and in health journals regarding “race or genetic specific” related health issues. Obviously I’m personally invested in finding out more information.
Maybe it’s the same with Cichlids; some are simply prone to a particular disease which in this case is “bloat”. (It’s strange how an “African Cichlid disease” is referred to when any fish “bloats”)
Bloat in fish can be cured, such as it is. I have cured what we call bloat in a number of Cichlids including Tropheus sp. and H. beani more than once. I’ve also been able to prevent it while others keeping the same fish, even the same strain, have suffered complete losses. The key is to catch it early on in the progress of the syndrome. I call it a syndrome because no one has definitively diagnosed what bloat is in fish. In the medical community an unknown or undefined disease is referred to as a syndrome. Conversely, bloat in dogs is a known and treatable disease.
My “cure” is to catch it early as I mentioned, treat with Epsom salts, ¼ cup per 10 gallons and STOP feeding!! I don’t raise the water temperature or use any other medications unless I see a secondary infection setting in. Additionally, if possible isolate the fish in a dark quiet area of your fish room.
My “prevention” regimen is NEVER over feed, NEVEER feed just before lights out and keep your water as clean as possible! Over feeding, especially here in the states is a real problem. People want to grow their charges as fast as they can so they can breed and sell babies in the pursuit of the almighty dollar. In nature and fish hardly ever gets a hand full of food at one time. Ninety percent of the time they only get a small morsel of food while grazing on rocks and the substrate. Occasionally, since they are opportunistic feeders they may get a live fish or fry but for the most part its catch as catch can.
I never feed anything to my fish if the lights are scheduled to go off within the next couple hours. My theory here is how would you feel if you ate a huge meal then tried laying down to sleep? Your body is going to try sleeping and processing the food at the same time, it doesn’t make for a comfortable night and doesn’t do you stomach and intestines and favors either.
As for water quality it’s a matter of time and attention. I opted to develop an automatic water changing system. It runs twice daily for 30 minutes on every zone, my tanks are arranged in five zones. For example, a 100-gallon tank receives 10 gallons of water a day in two 5-gallon increments. Fry and adults alike really responded positively to this set up and I would never provide less fresh water like I used to once a week again. My new fish room will receive larger water changes after I add my R.O. unit discharge to the system.
PS. Not to brag but I've been successful (lucky) breeding H. beani again. I could not keep them from murdering each other in large tanks but mom is doing a fime job raising the fry on her own. Dad is in quarantine until I remove the fry.... A shot of mom and dad.