The temperature in Lake Victoria ranges from about 21-27°C (70-81°F). The pH ranges from 7.1-9. The temperature in Lake Malawi ranges from about 23-28°C (73-82°F). The temperatures can go as low as 20°C(68°F) and as high as 30°C(86°F) on occasion. The pH ranges from 7.8-8.5. As long as you have somewhat hard water than your fish will be fine. Our local water is only about 223 ppm. I've never had any problems raising and breeding any Victorian, Malawian or even Tanganyikan fish.
So I can keep it come up with a good even temp between temps of lake victoria and malwai by taking an in between fish temp of the two lakes and do a math problem to figure a in between that would be Ideal for them and do the same with the ph.
I keep and breed all my africans from all lakes and rivers that i have had over the past year and a half at 72-76F depending on what season it is and a pH of 6.8-7.2 depending on how seasoned the tank is. Thats just my 2 cents. Dustin B.