Taxonomy & naming
Haplochromis melanopus was described by the British ichthyologist Charles Tate Regan in his 1922 revision 'The Cichlid Fishes of Lake Victoria' (Proceedings of the Zoological Society of London 1922: 165, fig. 1), the paper in which he restructured the great Victoria flock and brought order to Boulenger's sprawling earlier catalogue. The original combination was Haplochromis melanopus, based on a series of seven syntypes in the Natural History Museum, London (BMNH) — three from Entebbe and four from Bunjako, both on the Ugandan shore of Lake Victoria, which together fix the type locality. The Catalog of Fishes and the CLOFFA check-list (van Oijen et al. 1991) both retain the name as valid as Haplochromis melanopus Regan 1922.
The genus assignment, however, is genuinely unsettled. 'Haplochromis' in the strict sense is the type species' genus, and the hundreds of Lake Victoria species long parked there are widely regarded as a paraphyletic holding pen awaiting revision. In his 1980 reclassification of the Victoria flock, P. H. Greenwood transferred this species to Astatotilapia, and the Cichlid Room Companion accordingly lists it as Astatotilapia melanopus (Regan, 1922), with Greenwood, 1980 as the new combination. ETYFish likewise notes it is 'sometimes placed in Astatotilapia.' We keep the long-familiar Haplochromis heading here, as most databases still do, while flagging Astatotilapia as the modern alternative. Greenwood's revisionary work also folded some earlier nominal forms into a broadened concept of the species, so the historical synonymy around the melanopus name is not entirely clean.
Morphology
This is a small cichlid: FishBase records a maximum of about 4 in total length, and like most generalised Lake Victoria haplochromines it would have been an unremarkable, laterally compressed, moderately deep-bodied fish in life. The single diagnostic feature preserved in its name is coloration of the fins — Regan's epithet melanopus, 'black-footed,' refers to the blackish pelvic ('foot') fins of the type specimens. Beyond that, detailed morphometric and meristic data specific to this species are thin in the accessible literature; the formal characters that separate it from its many near-identical congeners live in Regan's original description and Greenwood's later revision rather than in any modern field guide.
As is the rule across the Victoria flock, the sexes almost certainly differed in colour: breeding males of these haplochromines are typically the brightly pigmented sex, developing nuptial hues and the yellow or orange 'egg-spots' (ocelli) on the anal fin that play a role in spawning, while females and non-breeding fish are a drab silvery-brown. We have no published, species-specific account of nuptial male colour for Haplochromis melanopus, so any statement of sexual dimorphism beyond the genus-typical pattern would be speculation.
Habitat
Haplochromis melanopus is endemic to Lake Victoria, the world's largest tropical lake and the shallowest of the African Great Lakes (maximum depth only about 262 ft, mean depth around 131 ft). The verified records are from the Ugandan sector — the type material came from Entebbe and the Bunjako area on the northern shore — and the IUCN assessment notes the species has not been confirmed from the Tanzanian waters of the lake. Eschmeyer's Catalog gives its distribution simply as 'Eastern Africa: Lake Victoria.'
No in-situ chemistry was recorded for this particular fish, but Lake Victoria's surface waters are well characterised and warm and alkaline by the standards of a soft-water aquarium: inshore temperatures generally run about 75–81 °F, pH is circumneutral to distinctly alkaline (roughly 7.1 up to 9 in productive bays), and conductivity is low-to-moderate at around 90–100 µS/cm. The lake is shallow enough that most of its endemic haplochromines occupy the upper few metres of the littoral and sublittoral zone — sandy, muddy, rocky and vegetated shallows rather than the open deep — and a small species like this would have lived in that nearshore band. We record an indicative shallow-water depth range with that caveat rather than a measured figure, since FishBase carries no depth data for the species.
Feeding
No gut-content study specific to Haplochromis melanopus appears in the accessible literature, so its exact diet is undocumented. FishBase places it at an estimated trophic level of about 3.3, which points to a generalised carnivore or insectivore-leaning omnivore rather than a strict herbivore or a top piscivore. The Lake Victoria flock as a whole was the textbook example of explosive trophic diversification: from a small number of riverine ancestors it radiated into algae-scrapers, leaf-choppers, detritivores, mollusc-crushers, insect-pickers, zooplanktivores, prawn-eaters, scale-eaters, paedophages (egg- and larva-snatchers) and large piscivores, all built on a very similar body plan. A small, generalised species of melanopus' size and trophic level most plausibly fed on insect larvae, small invertebrates and associated detritus gleaned from the nearshore substrate, but in the absence of a published diet that placement is inferential, not observed.
Mating
Direct courtship observations for this species do not exist in the literature, but the reproductive behaviour of Lake Victoria haplochromines is one of the best-studied mating systems in fishes and the genus pattern can be stated with confidence. These cichlids are polygynous and do not form pair bonds: males establish and defend a small territory or a cleared spawning site, advertise to passing females with intense nuptial colour and lateral-display and quivering 'leading' behaviour, and mate with any receptive female that responds. Females visit, spawn, and then leave to brood alone. Mate choice in the flock is strongly driven by male colour, and divergence in male nuptial hue (and in female colour preference) is thought to be a major engine of the lake's explosive speciation. For Haplochromis melanopus specifically, the only surviving clue to its sexual signalling is the dark pelvic fins that gave it its name.
Breeding
Haplochromis melanopus is a maternal mouthbrooder — FishBase records 'mouthbrooding by females,' the universal reproductive mode of the Lake Victoria haplochromine flock. In this system the female takes the fertilised eggs into her mouth immediately after spawning (often snapping at the male's anal-fin egg-spots, which helps ensure fertilisation), then carries and oxygenates the clutch in her buccal cavity for roughly two to three weeks without feeding, releasing fully formed free-swimming fry and briefly sheltering them in her mouth again when threatened. No clutch count was ever published for this species; small Victoria haplochromines of this body size typically carry only a modest brood, on the order of a few dozen eggs (commonly cited genus-typical figures run from roughly 20 to 80), which is the trade-off these fish make for the high survival that prolonged oral incubation buys. Parental care is entirely by the female and ends soon after the fry are released; the male contributes nothing beyond spawning.
In the aquarium
Haplochromis melanopus is not a fish of the aquarium hobby. It has no established trade presence, no documented captive husbandry or breeding, and is not offered commercially; an aquarist is far more likely to encounter it as a museum syntype or a line in a check-list than as a living fish. That silence is partly a function of how little is known about it and partly a consequence of history — much of the Victoria flock was decimated before the species could be studied alive, and many of its members, this one included, may persist only patchily or be effectively unobtainable.
What can be said is generic, by analogy to the small Lake Victoria haplochromines that ARE kept (the so-called 'Victorian Haps' maintained by conservation-minded specialists). Those fish are managed as hard-water, alkaline-water cichlids — pH on the alkaline side of neutral, moderate to high hardness, and warm temperatures around 75–81 °F, mirroring the lake — in tanks with open sand, rockwork and line-of-sight breaks. They are typically kept in groups with a surplus of females, because territorial males harass females hard, and they hybridise readily with related haplochromines, so single-species management is essential. None of this is documented for Haplochromis melanopus itself; it should be read as the husbandry its relatives require, not as a keeping record for this species, which to our knowledge has never been maintained in captivity.
Conservation
The IUCN Red List assesses Haplochromis melanopus as Data Deficient (assessed 31 March 2010 by Witte, F. & de Zeeuw, M.P.; published 2010). The assessors note that the species is endemic to Lake Victoria and confirmed only from the Ugandan sector, with too little information on its current distribution, abundance and population trend to assign a threat category — its population trend is listed as unknown. It carries no CITES listing.
That data gap sits against one of the most severe conservation episodes in modern freshwater history. Lake Victoria once held 500-plus endemic haplochromine cichlid species, more than any other lake on Earth, comprising the great majority of the fish biomass. From the 1980s the deliberately introduced Nile perch (Lates niloticus), a large predator, combined with worsening eutrophication, declining water clarity and oxygen, and heavy fishing, drove an estimated 40 percent or more of the flock to extinction or near-extinction in a matter of decades — the most rapid mass loss of vertebrate species ever recorded. Some haplochromines have since rebounded in shallow, rocky and vegetated refuge habitats as the Nile perch population was fished down, but many small, narrow-range species that were never properly documented remain of genuinely uncertain status. Haplochromis melanopus is one of them: it is not known to be safe, and it is not confirmed lost — it is, precisely, data deficient.