Taxonomy & naming
The species was described by the French ichthyologist Jacques Pellegrin in 1904 as Paratilapia victoriana, in the Bulletin de la Société Zoologique de France, on a single specimen from Kavirondo Bay (the Winam Gulf) at the northeastern, Kenyan end of Lake Victoria. That unique holotype, MNHN 1904-0148, is held in the Muséum national d'Histoire naturelle in Paris and was catalogued by Blanc in 1962; Pellegrin figured the fish the following year (1905, plate 16). The name was later transferred to the catch-all East-African genus Haplochromis, the combination Haplochromis victorianus (Pellegrin 1904) being formalised in the CLOFFA checklist treatment of van Oijen and colleagues (1991), and that is the name under which it is universally listed today. The Lake Victoria haplochromine flock has been repeatedly split into smaller genera by various authors, and a piscivore of this kind would fall within the assemblage often placed in the genus or subgenus Prognathochromis; because that finer-scale taxonomy remains unsettled and is not consistently applied, the atlas keeps the species under the conservative Haplochromis heading. It is one of several Lake Victoria species Pellegrin named in the same 1904 work, a foundational early account of the lake's then barely-known cichlid fauna.
Morphology
Detailed morphometric description of this species is scarce in the accessible literature, and no photograph of a living fish appears to survive. What is documented is its size: FishBase records a maximum of 6.5 in standard length, placing it among the medium-large members of a flock whose species mostly fall between roughly 8 and 8 in. Its general build is that of a Lake Victoria piscivorous haplochromine — an elongate, laterally compressed body with a relatively large, well-toothed mouth suited to seizing other fish. Like the rest of the flock it would have shown the haplochromine pattern of bright, sexually dichromatic breeding males (typically blue, red or yellow with a row of orange 'egg-spot' ocelli on the anal fin) against drabber, silvery-brown females; the colours in life were never recorded in detail for this particular species. Sexual dimorphism is therefore assumed present on the strength of the near-universal pattern in the group rather than from a published description of victorianus itself.
Habitat
Haplochromis victorianus is endemic to Lake Victoria, the vast shallow lake straddling the equator between Kenya, Tanzania and Uganda (FishBase gives its latitudinal band as about 1°N to 3°S). It is a fish of the lake proper rather than its inflowing rivers. Within the lake it occupied sheltered areas over soft mud bottoms, and FishBase records it from a depth range of roughly 20–39 ft — the sub-littoral muddy shelf that supported a large part of Victoria's benthic haplochromine community. Lake Victoria is warm, well-mineralised, alkaline freshwater: surface temperatures generally run in the mid-20s Celsius, and pH is typically alkaline, in the region of 7.5 to 9. The mud-bottom habitat this species favoured is also the part of the lake most affected by the eutrophication and deoxygenation that overtook Victoria in the later twentieth century, as well as being prime hunting ground for the introduced Nile perch.
Feeding
This is a piscivore — a fish-eater. FishBase records its diet simply as 'small fish,' and assigns it a high trophic level of about 4.2, consistent with a predator near the top of the haplochromine food web. Piscivory is one of the major trophic guilds into which the Lake Victoria haplochromine radiation diversified; the lake produced a whole array of fish-eating haplochromines that hunted juvenile cichlids and small open- and bottom-water prey across the muddy and vegetated zones. Haplochromis victorianus belonged to this predatory guild, taking small fish from the sheltered soft-bottom habitats it occupied. Beyond the prey category, the fine mechanics of its hunting and any seasonal shifts in diet were never studied in detail before the population collapsed.
Mating
No courtship or social behaviour has been described specifically for Haplochromis victorianus, and what can be said rests on the strongly conserved biology of the Lake Victoria haplochromine flock. These fish are maternal mouthbrooders with a lek-like or loosely territorial mating system: ripe males develop intense nuptial colour and court females actively, and a female that accepts a male spawns with him before taking sole charge of the brood. The bright, species-specific male colours and the females' colour-based mate choice are thought to have been a central engine of the explosive speciation that produced several hundred haplochromine species in the lake — and, conversely, the loss of that visual signalling under the lake's modern turbidity is implicated in the breakdown of species boundaries. For victorianus specifically, the courtship was never recorded.
Breeding
Like essentially all Lake Victoria haplochromines, Haplochromis victorianus is a maternal mouthbrooder: the female takes the fertilised eggs into her mouth and incubates them there, and after the eggs hatch she continues to shelter the free-swimming fry in her buccal cavity for a period, releasing them to forage and gathering them back in at any threat. No clutch count, egg size, incubation time or fry-development data were published for this species before its decline; haplochromines of the flock typically produce small clutches — of the order of a few dozen eggs, far fewer than open substrate-spawning cichlids — as the trade-off for the intensive oral brood care. The specifics for victorianus are simply undocumented, and given its conservation status are unlikely ever to be observed.
In the aquarium
Haplochromis victorianus is not an aquarium fish in any meaningful sense. It has no presence in the ornamental trade, no established hobby strain, and — being Critically Endangered and very possibly extinct in its only home, Lake Victoria — there is no legitimate supply of wild or captive-bred stock. Unlike the handful of charismatic Lake Victoria haplochromines that hobbyists and public aquaria have maintained as conservation 'ark' populations (the so-called Victoria basin survivors kept under code names and trade labels), this species was not among those rescued into captivity before its collapse. Anyone keeping Lake Victoria haplochromines in general should know they are warm-water fish (about 73–81 °F) that need hard, alkaline water (pH roughly 7.5 to 9), generous swimming space, and careful management of the male aggression and hybridisation that come with the flock's lek-breeding biology. But for victorianus itself the honest statement is that it is not kept, and almost certainly cannot be.
Conservation
The IUCN Red List assesses Haplochromis victorianus as Critically Endangered (Possibly Extinct) under criterion C2a(ii), assessed on 31 March 2010 by Witte, de Zeeuw and Brooks, with a decreasing population trend; Eschmeyer's Catalog of Fishes goes further and lists the species' status flatly as extinct. It is one casualty among the hundreds of endemic haplochromine cichlids lost or driven to the brink in the catastrophic restructuring of Lake Victoria's ecosystem in the late twentieth century. The dominant driver was the introduction of the predatory Nile perch (Lates niloticus), which spread explosively through the lake between about 1979 and the late 1980s and consumed vast numbers of native haplochromines; by the 1990s well over 200 endemic cichlid species were estimated to have been driven to extinction or near-extinction. Acting alongside the perch were heavy eutrophication and bottom-water deoxygenation from catchment nutrient loading, water turbidity that collapsed the colour-based mate recognition holding species apart, and intensive fishing. A mud-bottom, sub-littoral piscivore such as victorianus was exposed to nearly all of these pressures at once. No confirmed records of the species are known from recent decades, and while the IUCN stops just short of declaring it extinct, the prospects for its survival are bleak.