Note: Since writing this, it appears exportation has resumed, perhaps from a different part of the lake. It's also not unheard of for a little money to exchange hands to allow some divers a few hours within the Park's borders. Who knows.
As one might imagine, Ps. flavus are a lot like Pseudotropheus elongatus, both in size and shape, not to mention temperament. Males are unusually territorial, hunting for food around their own claimed rock, and defend their district against any intruder. It is suggested that males be kept with females in a ratio of 1 male to 3 or even four females. This is because males are very aggressive to one another and females do not group together. Ps. flavus is best kept in an aquarium of 75 gallons or larger.
The males of this rare species are very colorful, but the females tend to be a dingy mix of shaded yellow to brown. This mbuna also grows long and slender. In the wild, it usually grows to a maximum Female Pseudotropheus flavusof 3 inches (8 cm) in length, males being a slightly larger than females. Because of their smaller size they have been grouped among the Pseudotropheus dwarf species. In captivity, however, this fish can easily reach a maximum length of 4 or 5 inches (10 - 12.5 cm). In my experience, they begin to show their adult coloration at as early as 2 inches (5 cm). In the wild, Ps. flavus is found among the sedimentary rocks of Chinyankwazi Island's reef, at a depth of 7 to 20 m. This mbuna is an omnivore, subsisting primarily upon the plankton in the open water and the algae that grows on rocks. For the aquarium, I recommend a Spirulina-based flake food.