Umbees are the most sensitive to water quality and require very clean waters. They also seem to be more sensitive to nitrates than many other cichlids. Alot of umbee owners do not realize this and probably why we do not see many full grown umbees. One more reason why they are prone to health problems may be due to the bloodline being siblings created from siblings for decades now.
Bigger tank, bigger buffer, bigger water changes, longer life. And as mentioned previously, they are open water predators.