Endemic to Lake Tanganyika where it is recorded from the northern part of lake where only three subpopulations have been found, namely: 1) "Bemba" which cohabits with the orange morph of Tropheus moorii morii on a very narrow stretch of coastline, less than 1 km long, around Cape Munene (the village of Bemba no longer exists). This relict population, more than 160 km from the next one in Tanzania on the east coast, involves a few thousand fish at most; 2) "Kigoma": This is the largest known population of T. duboisi, stretching from the border between Tanzania and Burundi, south of Nyanza Lac, to the Malagarazi River. Distributed along nearly 100 km of coastline, this population involves tens of thousands of fish. It shares its habitat with Tropheus brichardi. Broad yellow band. 3) "Malagarazi duboisi": The broad-banded T. duboisi has been found around the Malagarazi River delta but its full range is as yet unknown. By the mid-1983 a new very broad-banded yellow variety, whose whereabouts have not been identified, has been exported from Tanzania. It doesn't appear to be significantly different from the specimens previously exported.