Algal "Gardeners" — the Pseudotropheus "Aggressive" Assemblage
Above:Pseudotropheus "aggressive brown," a male photographed
at Thumbi Island West, Cape Maclear, Malawi.
Photo by Ad Konings, reproduced with his permission from
Konings (1995c). Members of the
Pseudotropheus "aggressive" species group, first proposed
by Ribbink et al. (1983: 190),
do not share any known morphological synapomorphy and are not
thought to constitute a natural, monophyletic group.
The "aggressives" do, however, share a couple of unusual behavioral
characteristics. The included species—males and females
alike—defend territories so aggressively that they prevent
other fish from feeding there, so that "gardens" of filamentous algae
develop within the territory. The aggressive fish feed on loose
Aufwuchs, such as diatoms, combed from the filaments, sometimes
supplemented with insect larvae, small crustaceans, and other benthic
invertebrates, or with plankton. Some species belonging to the
Pseudotropheus elongatus group are also sufficiently
territorial that they can be algal "gardeners,"
but those species differ in having more elongate bodies.
