On November 2nd, 1996, I purchased a pair of wild-caught fish, labeled Pseudotropheus sp. "Msobo Deep" at my local fish store, for $36. The male was about 2" and is mottled blue/black, and the female was about 1.5" and is a solid bright orange color. Both are clearly far from their full adult size.
My pair is breeding, in my 75 gallon Mbuna tank. First spawning was in Feb 1997, and the second in May 1997. I have not been removing the female from the tank (mostly because it's very difficult to catch her), and most of the fry she releases have been eaten. From the first brood, only one has survived. The second brood was released 6/8/97, and so far (7/9/97) I've seen at least 5 fry hiding in the tank. As of 8/3/97, it seems that there are 4 fry that have survived, and are happily living in that tank.
I noticed her carrying eggs again on 7/8/97. And this third brood was released on 8/2/97, after I managed to get the female into a 10 gallon tank by herself, so hopefully most fry will survive. She released them into this tank. By initial rough counts, there are about 27 fry. On 8/3/97 I moved the female back into the main 75 gallon tank.
I was able to find very little information about this (apparently undescribed) species, so I figured that I'd collect what information that I could find, and put it up on the web.
The Mbuna Coast Aquatics fish distributor is selling something which they call Pseudotropheus msobo "deep water" Tanzania' and note that it is also known as "sp. deep". Unfortunately, they have no picture online, so I can't tell if this is the same fish as I have.
To give some reference, it looks similar, but not quite identical to: Ps. sp. "Membe Deep" as photographed on page 399 on Ad Koning's Book of Cichlids and all the other fishes Of Lake Malawi (1990). The female looks essentially identical. But, the pattern on the male is different, the Msobo male being more blotchy (but has similar overall colors).
In Ad Konings Malawi cichlids in their natural habitat (in German) both these fish, and one called Ps. "Msobo heteropictus", are mentioned in the chapter "The Msobo trio".
Ps. "Membe deep" can be found at the north-eastern coast of Likoma island. While Ps. "Msobo" can be found between Cape Kaiser and Lundu and Ps. "Msobo heteropictus" between Njambe and the Lundo islands.
The "Msobo" lives in the upper regions but at Magunga reef it can also be found in the rocky parts. On some males the coloration looks more like 2 horizontal stripes. This gives some evidence that they could be related to the Melanochromis species, but they eat the aufwuchs the same way Ps. zebra does.
At the printing of this book, the "Msobo" hadn't been put in either of those groups.
After reading that about Melanochromis, I rechecked Ad Koning's Book of..., and found that M. sp. "Chisumulu Johanni" (photos pages 332, 333) is very similarly colored to the "Msobo Deep"s. The "Chisumulu Johanni" male has more black and less blue than my male "Msobo Deep". But my male's coloration does indeed somewhat show the horizontal lines of the typical of the Melanochromis genus.
My female, however, has a very pronounced black-spot on the "end" of her operculum (which shows in the correct lighting conditions). The Koning "Membe Deep" photo has a lighter dark spot there. The Koning "Chisumulu Johanni" photo shows no darkening.