Taxonomy & naming
The British-Belgian ichthyologist George Albert Boulenger described this fish in 1906 as Tilapia lacrimosa, in the Annals and Magazine of Natural History, from specimens collected at Entebbe on the Ugandan shore of Lake Victoria (then Victoria Nyanza), which stands as the type locality. Boulenger's account was one of the earliest scientific treatments of the lake's cichlid swarm, in an era when nearly all of these fishes were lumped into Tilapia. Peter Humphry Greenwood, who spent decades disentangling the Victorian haplochromines, formally moved the species into Haplochromis and in 1960 selected a lectotype (BMNH 1906.5.30.471, in the Natural History Museum, London) from Boulenger's original series of syntypes, the rest of which became paralectotypes. The combination Haplochromis lacrimosus has been treated as valid ever since, including in the CLOFFA checklist of van Oijen and colleagues (1991). As with most of Lake Victoria's roughly 500 haplochromine species, the genus assignment is unsettled: the great flock is so young and so densely speciated that authors have at various times shuffled its members among Haplochromis, Astatotilapia, Yssichromis and other genera, and lacrimosus is sometimes placed in Astatotilapia. The atlas keeps the long-standing Haplochromis heading, under which the species is universally indexed.
Morphology
This is a small cichlid: FishBase gives a maximum of about 4 in standard length, and like most of its lake-mates it is a slender-to-moderately-deep, laterally compressed haplochromine of generalized build. The single feature that names and diagnoses it is on the face. The species epithet lacrimosus is Latin for "tearful" or "weeping", and it refers, in the words of the etymological literature, to a "black vertical bar below the anterior third of the eye" — a dark teardrop-shaped marking dropping from the front of the eye, occasionally faint or absent but normally the clearest field character. Beyond that lachrymal bar, detailed external description is thin in the accessible sources, which is typical of the many small Victorian haplochromines that were named from museum series rather than from living, coloured fish. Sexual dimorphism is not documented in detail for this species, but it can be inferred with confidence from the group: across Lake Victoria haplochromines, breeding males are the brightly coloured sex (often blue, yellow or red with black markings and egg-spots on the anal fin) while females and non-breeding fish are a drab silvery-brown, and the male is typically the slightly larger and more ornamented of the two.
Habitat
Haplochromis lacrimosus is endemic to Lake Victoria, the vast, shallow, equatorial lake shared by Uganda, Kenya and Tanzania; the species is documented from the Ugandan shore (Entebbe) and the Kenyan shore (the Natural History collection includes material from near Port Florence, now Kisumu). FishBase characterises it as an inhabitant of exposed sandy beaches — a sand-and-shoreline fish rather than a rock-dweller or an open-water form. It is recorded from the surface down to about 20 ft, which places it firmly in the shallow littoral zone. Lake Victoria's water is warm and moderately alkaline: FishBase gives a temperature range of roughly 73–79 °F for this species, a pH of about 7.0–8.0, and hardness up to around 25 dH, all consistent with the lake's well-buffered, mineral-rich waters. Because the lake straddles the equator it shows little seasonal temperature swing, and the shallow sandy margins where this fish lives are warm year-round.
Feeding
The stomach contents tell the story of a bottom-feeding sand-sifter. Examined specimens contained fine sand grains together with bottom detritus — including fragments of plant epidermis and the silica frustules of diatoms — plus some small crustaceans (Cladocera) and insect larvae. That mixture is the signature of a fish that takes mouthfuls of the sandy bottom, swallows the edible organic film, diatoms and tiny invertebrates, and passes the mineral sand through. FishBase places it at a trophic level near 2.8, low on the food web, consistent with a detritivore/benthic-invertivore rather than a predator. In the trophic classification of Lake Victoria's haplochromine flock — which sorts the species into more than a dozen guilds such as algae-scrapers, mollusc-crushers, insectivores, zooplanktivores, paedophages and piscivores — Haplochromis lacrimosus belongs among the bottom-feeding detritivore/insectivore sand-dwellers of the shallow littoral, one of the many small species that together processed an enormous share of the lake's benthic production before the ecosystem was upended.
Mating
No courtship study specific to Haplochromis lacrimosus is available, but its reproductive biology can be placed confidently within the well-studied Lake Victoria haplochromine pattern. These cichlids are not pair-bonding substrate guarders; they are polygynous maternal mouthbrooders in which the sexes meet only briefly to spawn. A ripe male takes up a small temporary territory or display arena on the bottom — over sand, in this species' habitat — and courts passing females with intense colour and quivering displays, using the egg-spots on his anal fin as a lure. Females, drab and inconspicuous, move through the arenas and choose among displaying males; female mate choice on male nuptial colour is the engine that is thought to have driven the explosive speciation of this flock. After spawning the male's role ends, and the female alone carries and tends the brood.
Breeding
Haplochromis lacrimosus is a maternal mouthbrooder, as FishBase records plainly ("mouthbrooding by females") and as is universal among Lake Victoria haplochromines. The female takes the fertilised eggs into her mouth and broods them there through hatching and the early free-swimming stage, eating little or nothing for the duration; in many Victorian haplochromines she continues to shelter the fry in her buccal cavity for a period after they can swim, taking them back in at any disturbance. Species-specific figures for this fish — exact clutch size, brooding duration, fry size at release — have not been published; for context, small Lake Victoria haplochromines of this body size typically carry modest broods on the order of a few dozen eggs (commonly cited ranges run from roughly ten to a few tens of eggs in the smaller species). The maternal-mouthbrooding strategy, with its small clutches of large, well-provisioned young and prolonged buccal care, gives the fry a strong survival advantage and is one reason the flock could pack so many species into a single lake.
In the aquarium
Haplochromis lacrimosus is essentially never seen in the aquarium hobby. It is a small, plainly described, scientifically obscure Lake Victoria sand-dweller with no established trade in it, no common name, and no published aquarium husbandry — and it should not be confused with the handful of colourful Victorian haplochromines (such as the "Zebra Obliquidens" or various Pundamilia and Astatotilapia) that conservation-minded keepers do maintain. If a true specimen were ever kept, the general requirements of the group would apply: hard, alkaline water around pH 7.5–8.0 and 73–79 °F, matching the lake; a sandy bottom suited to a fish that sifts substrate; and an open, well-filtered tank. Lake Victoria haplochromines are robust and adaptable but are also fast-breeding and pugnacious, so the standard approach is a single male with several females and ample retreats to spread male aggression. The honest assessment, though, is that this species has no presence in the hobby and the more important context for it is conservation, not keeping.
Conservation
The IUCN Red List assesses Haplochromis lacrimosus as Data Deficient (assessment by F. Witte and M.P. de Zeeuw, assessed 31 March 2010, published 2010), with an unknown population trend — a verdict that means there is simply not enough information to judge its status. That uncertainty is the central fact of its conservation story. From the 1980s onward the introduced Nile perch (Lates niloticus), a large predator, exploded in Lake Victoria and was implicated, alongside eutrophication, overfishing and the spread of water hyacinth, in the catastrophic decline of the lake's haplochromine flock; a large fraction of the estimated 500-plus endemic haplochromine species crashed, and many are feared extinct or have never been seen since. When Nile perch were heavily fished down in the 1990s, some haplochromine species rebounded, but the recovery was uneven and many did not return; bottom-dwelling detritivores and insectivores of the kind Haplochromis lacrimosus represents fared variably. The threats the Red List records for this species — invasive predators, fishing pressure, and pollution from domestic, industrial and agricultural sources — are precisely the pressures that reshaped the lake. Whether this particular small sand-dweller persists in stable numbers, hangs on in refuge habitats, or has quietly disappeared is genuinely not known, which is exactly why it sits in the Data Deficient category rather than a more or less threatened one.