I agree with DJRansome on the NLS or NorthFin. I used New Life Spectrum exclusively for 15 years. I have switched over to NorthFin these last three years. I think they are both great. Don't want to get into a "best food" debate here.
Tanganyika fish are not the easiest to keep but I have had tropheus on three occasions and never lost even one, cyps, sand sifters, foai, wild caught frontosas - many fussy fish thriving and breeding for many years on one type of fish food - no home made meals, no frozen foods, etc. A good quality pellet.