P. demasoni is one the newest discoveries coming out of Lake Malawi, being identified and described by Ad Konings in 1994. And in 1999, P. demasoni was an ACA Class Winner. It has enjoyed a great deal of popularity (although still not yet very abundant), I believe, because of its sharp colors and crisp lines. It is similar in appearance to Pseudotropheus minutus, only that the latter's lines are less distinct and stop before the tail fin.
This is a dwarf Mbuna, and as such, can be housed in tanks not usually recommended for Mbuna species. A 36-inch tank will suffice, but as with all Mbuna, bigger is always better. In the wild, these fish are found together in extremely large groups swimming in and amongst rocky habitats. Surprisingly, members of these groups show very little aggression towards one another. In order to successfully keep a group in an aquarium, the same type of set-up should be simulated.
First and foremost, a minimum of twelve should be kept in any size tank to help disperse aggression. This not only keeps a single male from being dominant over all others, it helps females and sub-dominant males from being chased to exhaustion (and death) by getting "lost in the crowd". A small group of 5 or 6 simply will not work, as the dominant male will systematically kill off each tank mate until only he remains. Male to female ratio is unimportant when they're kept in groups of this size, which is a bonus, because accurately determining their gender can be a futile task. It's very important not to house these fish with similarly colored species (e.g., Cynotilapia afra or Metrialclima lombardoi).
A rocky habitat is also of utmost importance. They, unlike any other Mbuna, spend a lot time in caves and swimming around rocks - not because they are timid, but because they are curious. They also seem exquisitely territorial; therefore, the more caves and niches your aquarium has, the better off females and sub-dominant males will be. As an example, I vividly recall watching a ½" male chase a medium-sized venustus for over 6-feet just because he had shown some interest in the demasoni's cave. Demasoni are tough and can hold their own!
Like most Mbuna, demasoni are vegetarians and should be fed foods high in spirulina and other vegetable content. A high quality all-purpose cichlid formula will also work as a staple food. Males and females are equally colorful and reach a maximum size of 2.5 - 3". Broods consist of anywhere from 6 - 20 fry. This is largely dependent on the size of the female, as Ps. demasoni start breeding at a very small size, in some cases, at just over an inch!
In my personal opinion, there is no other Mbuna with more personality than this small dwarf Cichlid from Lake Malawi. They are curious, aggressive, elusive, quick, and interesting to watch. Perhaps their most unique behavior is the way they hug walls, rocks, caves, and the substrate. For some odd reason, their ventral side is never exposed. They tend to hover over rocks, etc., following their contour, even if this means they swim upside down, sideways, or at odd angles. It's really funny to watch; it just seems unnatural. This fish definitely has spunk and personality!