The life and death of most fish in captivity depends more on the quality of the water in fish tanks than of any other individual characteristic. Many die of overfeeding (not by excessive voluntary intake). But many fish die from shock or poisoning produced by water, rather than of any other possible causes related to the captivity. It is important for your pet, having some knowledge on the chemistry of the water in your fish tank and consult various texts on maintenance of tanks. Water has many features. It can contain almost any known gas, all soluble salts, having different colors and a range of temperatures ranging from 0.5 C, just above freezing, to 99.3 C, just below boiling. It can be from acid to alkaline, depending on materials dissolved in it. Read more here: Raymond James. Or it can contain a poison, such as DDT, which has the capacity to kill fish immediately.
All experienced breeders know the characteristics of your supply water intimately. You know if your local water company has changed the water inlet, or has added more chlorine to it. They know this because they see how fish react when they are installed in your ‘new’ water. What is what makes the fish reared in a water and die in another? Generally speaking we would say that the majority of fish works fine in neutral and soft waters. That is, water with a pH near 7.0. Many fish, especially those that disperse their eggs, put more quickly in acid water, with a pH between 6.4 and 6.8.
Most alate, moreover, so as many cichlids, seem to prefer slightly alkaline water with a pH close to 7.6. Some African cichlids prefer decidedly hard and alkaline waters, can thank a pH of up to 8.0. When you have a fish unknown in their hands, it is best to keep it in a water in which you assume that it will be OK.