The Prognathochomis genus is based on Pellegrin's 1904 description of Paratilapia prognatha. Closely related to the Harpagochromis lineage, Prognathochromis species have a slender body. The snout is pointed with a noticeable premaxilla protuberance. Prognathochromis are slender carnivores (most are piscavores) with large, slightly down turned mouths. The lower jaw extends past the upper giving the head a pointed "arrow" shape. When viewing the profile, the eye socket of Prognathochromis species is relatively even with the forehead slope. Teeth in the outer rows of larger fish (over 9cm) are stout and curved.
The subgenus Tridontochromis is differentiated by a small adult size (9.5-12cm) and protrusible jaws. As the name implies, Tridontochromis' main characteristic is the presence of tricuspid teeth in the outer row of both jaws. The pharyngeal bone contains fine compressed teeth.
The other subgenus, Prognathochromis usually reach a large adult size (14-23cm) except three species (10cm). Dentition consists of unicuspid teeth in adult individuals lining the outer row on both jaws. The eye protrudes slightly above the cranial slope. Internally, the pharyngeal bone is covered with noticeably more coarse teeth as compared with Tridontochromis species.
Prognathochromis sp. "silver stiletto" is not from Lake Victoria proper but rather Lake Nawampassa in the Kyoga Basin, located north of the great lake in Uganda. The introduction and subsequent reign of the Nile perch (Lates niloticus) in Lake Victoria has had a decimating impact on many cichlid species. Among the hardest hit were the piscavores including members of the Prognathochromis genus. Fortunately, many of the cichlid lineages of Lake Victoria have closely related representatives in surrounding waters.
In its natural habitat, Prognathochromis sp. "silver stiletto" inhabits areas of dense vegetation, especially reed laden areas when it "hangs" motionless amongst the plants (Kaufman, 2008). This feeding strategy of ambush predation is enhanced by the fish's silver coloration allowing the animal to appear nearly invisible amongst the gleaming sunlight. When an unsuspecting fish comes within range, Prognathochromis sp. "silver stiletto" darts out with lightening quickness. Small fish are devoured in a single strike while larger prey are attacked side on and severed in two pieces. Feeding almost exclusively on other fish, Prognathochromis sp. "silver stiletto" will occasionally take insects and soft invertebrates.
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