Taxonomy & naming
Haplochromis martini was described by the Belgian-British ichthyologist George Albert Boulenger in 1906 as Tilapia martini, on material collected at Bunjako on the northern (Ugandan) shore of Lake Victoria. The name later moved into the large, catch-all genus Haplochromis as the Lake Victoria flock was sorted out over the twentieth century; a lectotype is held in the Natural History Museum, London (BMNH). As is common for Boulenger's early Tilapia and Paratilapia names from the lake, the species was originally lumped with superficially similar fish, and the name was later applied (incorrectly) to other forms — an early-twentieth-century usage by Pappenheim and Boulenger treated 'Tilapia martini' only in part. The species belongs to the explosively radiated Lake Victoria haplochromine 'species flock', several hundred closely related cichlids that diverged in evolutionary fast-forward within the geologically young lake. Because that flock is so dense and so recently evolved, generic placement of its members is unstable: most are still carried under the conservative umbrella genus Haplochromis, even though many have been (or will be) reassigned to satellite genera such as Astatotilapia, Prognathochromis, Harpagochromis and others. We retain the familiar Haplochromis heading here. The specific epithet honours James Martin, a Transport Officer in the Uganda Protectorate, who was credited in Boulenger's account for assistance rendered to the collector Edward Degen, the Swiss ornithologist who gathered the type material.
Morphology
Haplochromis martini is a small cichlid, reaching about 4 in in standard length — modest even by the standards of the Lake Victoria flock, and typical of the lake's smaller predatory haplochromines. Detailed colour notes are scant, because no living aquarium strain is documented and the species is known largely from preserved museum and survey material; like most Lake Victoria haplochromines it would have shown the family's general plan of a moderately deep, laterally compressed body, a continuous dorsal fin, and (in nuptial males) bright structural colours used in mate choice, while females and non-breeding fish remained drab silvery-brown for camouflage. Sexual dimorphism is therefore presumed, following the near-universal pattern in the flock: breeding males develop conspicuous colour and the egg-spots (ocelli) on the anal fin that feature in haplochromine courtship, whereas females are cryptically coloured and carry broods in the mouth. Precise diagnostic features separating it from its many congeners rest in the original description and later revisions of the flock rather than in any field-recognisable trait, and the absence of photographs reflects how poorly the offshore haplochromines were documented before their collapse.
Habitat
The species is endemic to Lake Victoria, the largest tropical lake in the world (roughly 68,800 km2) and the centre of the East African Great Lakes haplochromine radiation; its range spans the lake's three riparian nations — Uganda, Kenya and Tanzania — within the Lake Victoria Basin freshwater ecoregion. Survey work recorded it on both exposed shores and in sheltered bays, over sand and over mud, but apparently not right up against the shoreline — an offshore-leaning, soft- and firm-bottom fish rather than a rock-dweller. FishBase gives a depth range down to about 39 ft, placing it among the sublittoral and offshore haplochromines that bore the brunt of the lake's twentieth-century ecological changes. Recorded water temperatures sit in the warm tropical band of roughly 75–79 °F. Lake Victoria water is naturally warm, well-buffered and alkaline; like other lake haplochromines the species would have lived in hard, alkaline conditions on the order of pH 7.2-9.0. A single more recent record of the species comes from Lake Bisina, a satellite lake within the wider Victoria system in Uganda, which — if confirmed — would be one of the few signs that it survives anywhere.
Feeding
Haplochromis martini is a piscivore: dietary records show it feeds mainly on fish, with dipteran (midge/chironomid) larvae taken as well. FishBase places it at a high trophic level of around 3.9, consistent with a predator that lives largely by eating other, smaller fish — in practice, mostly the juveniles and smaller members of the same dense haplochromine community. Lake Victoria's flock was famously partitioned into a fine mosaic of feeding guilds — algae-scrapers, detritivores, mollusc-crushers, insectivores, zooplanktivores, scale-eaters, paedophages and piscivores — and Haplochromis martini sat in the fish-eating guild. That trophic position made it doubly vulnerable to the arrival of the Nile perch (Lates niloticus): the perch is itself a large piscivore that both preyed on and competed with native fish-eating haplochromines like this one.
Mating
No courtship or social behaviour has been described specifically for Haplochromis martini, and it can only be discussed through the well-studied biology of the Lake Victoria flock to which it belongs. Lake Victoria haplochromines are polygynous maternal mouthbrooders in which mate choice is driven by male nuptial colour: males stake out small courting territories, display their breeding dress and the egg-spots on the anal fin, and females choose among them — colour-based female preference is thought to be a principal engine of the flock's explosive speciation. There is no pair bond; after spawning the female alone carries and tends the brood, while the male resumes courting other females. Whether Haplochromis martini's piscivorous, offshore habits implied looser or more dispersed courtship aggregations than the lake's rock-dwelling forms is unknown.
Breeding
Haplochromis martini is a maternal mouthbrooder: spawning, fertilisation and brood care follow the standard haplochromine pattern in which the female takes the eggs into her mouth, the male fertilises them there (the egg-spots on his anal fin are thought to help draw the female's snapping bites to release sperm), and the female then incubates the developing eggs and larvae orally for several weeks before releasing free-swimming fry. No clutch counts have been published for this species; Lake Victoria haplochromines of similar small size are typically modest-fecundity brooders carrying on the order of a few dozen eggs and larvae per clutch, trading egg number for the protection of oral incubation. Parental care is by the female alone, and continues after the fry are first released, with the young able to dart back into her mouth when threatened. No wild breeding triggers or seasonal data are documented specifically for Haplochromis martini.
In the aquarium
Haplochromis martini is effectively unknown in the aquarium hobby. It has no established captive strain, is not bred or traded, and — as a Critically Endangered, possibly extinct offshore species from the collapsed Lake Victoria flock — is not a fish that hobbyists encounter. There is therefore no husbandry tradition specific to it, and any keeping account would be pure extrapolation from its better-known relatives. For the small minority of Lake Victoria haplochromines that are maintained (mostly in conservation-minded breeding programmes and specialist aquaria), the general requirements are hard, alkaline water in the pH 7.2-9.0 range, temperatures around 75–79 °F, robust filtration, and the management of male aggression typical of the group — usually by keeping one male with several females in a spacious tank. None of that should be read as a recommendation to seek this species out: it is a wild fish on the brink, not an aquarium subject, and the honest statement is simply that it is not kept.
Conservation
The IUCN Red List assesses Haplochromis martini as Critically Endangered (Possibly Extinct) under criterion C2a(ii) (assessed 31 March 2010 by F. Witte, M.P. de Zeeuw and E. Brooks; population trend decreasing), reflecting both a tiny, fragmented surviving population (if any) and a continuing decline. The species is one of the many casualties of the catastrophic restructuring of Lake Victoria's fish community in the second half of the twentieth century. The introduction and explosive spread of the predatory Nile perch (Lates niloticus) from the 1950s-1980s, compounded by lake-wide eutrophication, declining water clarity and oxygen, and intensive fishing, is associated with the collapse of an estimated several hundred endemic haplochromine species — a loss often cited as the largest vertebrate mass extinction of modern times. Offshore, fish-eating haplochromines such as Haplochromis martini were among the hardest hit, both eaten by and competing with the perch. Its possible persistence in a satellite water such as Lake Bisina, where survey work has reported the species, hints that fragments of the flock may hang on in refugia outside the main lake, but for the open waters of Lake Victoria it is, at best, on the edge of extinction.