Taxonomy & naming
Haplochromis macropsoides was described by the British ichthyologist Peter Humphry Greenwood in 1973, in his revision of the Haplochromis and related species of Lake George, Uganda (Bulletin of the British Museum (Natural History), Zoology, vol. 25). The holotype (BMNH 1972.6.2.718) was collected at Kankurunga Island in Lake George, with a substantial series of paratypes from the same lake. The name is a direct nod to another member of the flock: macropsoides means 'resembling Haplochromis macrops', the species pair being so alike that Greenwood treated overall similarity as the defining cue. The genus name Haplochromis has long been a catch-all for the East African haplochromine radiation, and modern systematics has split much of that assemblage among genera such as Astatotilapia, Pseudocrenilabrus, Yssichromis and others; many authors would today place the Lake Edward-system 'Haplochromis' in or near Astatotilapia. Because no formal recombination has been universally adopted for this species and FishBase, the Catalog of Fishes and the IUCN all retain the original binomial, this profile keeps the Haplochromis heading while noting the unsettled generic placement. The species is one of roughly sixty haplochromine cichlids that make up the endemic flock of the Lake Edward drainage, a younger offshoot of the same great-lakes radiation that produced the far larger species flock of Lake Victoria — a table of the flock cited by Konings puts only 29 of those roughly sixty species as formally described, leaving well over thirty awaiting description, most likely concentrated in the far less thoroughly surveyed Lake Edward itself rather than in the better-studied Lake George.
Morphology
This is a small cichlid: FishBase lists a maximum of 3 in standard length, and like most members of its flock it is a slender, laterally compressed fish rather than a deep-bodied one. The diagnostic feature implied by its name is the eye — macropsoides points to the large-eyed condition it shares with Haplochromis macrops, and a relatively big eye is consistent with a fish that feeds in dim or turbid water and partly off the bottom. Greenwood himself stressed how difficult the species is to tell apart in the field from two of its neighbours, Haplochromis nigripinnis and Haplochromis elegans, and it is precisely this confusion that has left so little recorded about it. As in virtually all haplochromines, breeding males would be expected to develop the brightest nuptial colour, typically with egg-spots (ocelli) on the anal fin, while females and non-breeding fish stay a more cryptic silvery-brown; no detailed colour description for ripe males of this particular species is available in the accessible literature, so its precise nuptial pattern is best treated as undocumented here.
Habitat
Haplochromis macropsoides is endemic to the Lake Edward system of the western (Albertine) Rift in Uganda. It is recorded from Lake George and the Kazinga Channel — the shallow strait that links Lake George to Lake Edward — but, per Greenwood's account, it has not actually been recorded from Lake Edward itself. Konings judged an occurrence there reasonable to assume, since the Kazinga Channel habitat is nearly identical to Lake George's and closely resembles conditions near the channel's outflow into Lake Edward; that is a plausible inference, however, not a confirmed record, so Lake Edward occurrence is best read as probable rather than documented. Within Lake George it has been collected close to the papyrus fringes of islands and in more exposed water offshore of those islands, over mud bottoms. Lake George is a small (about 250 km2), exceptionally shallow equatorial lake with a mean depth of only around 8 ft; the whole basin sits in the shallow photic zone, so a meaningful depth band for this fish is essentially 0–13 ft. The lake is permanently eutrophic, carrying a dense, year-round crop of phytoplankton overwhelmingly dominated by blue-green algae (cyanobacteria), and its straddling-the-equator position gives it an unusually constant physicochemical environment that cycles on a 24-hour rather than a seasonal rhythm. Waters of the Lake Edward system are warm and alkaline: regional surveys report temperatures broadly in the low-to-high 20s Celsius and pH values that run distinctly basic, up into the 8–9.4 range in parts of the basin. In the FEOW scheme the entire drainage falls within the Lake Victoria Basin freshwater ecoregion, which is defined to include the basins of Lakes Victoria, Edward, George, Kyoga and Kivu.
Feeding
Haplochromis macropsoides is an insectivore. The specimens Greenwood examined had been feeding on dipteran (true-fly) larvae and pupae — in a lake this productive, the larvae and pupae of midges (chironomids) and related flies are a vast food resource. Tellingly, the absence of phytoplankton or sand grains in the stomachs he looked at suggested the fish were taking this insect prey away from the bottom, in open or mid-water, rather than grubbing through the sediment. That feeding mode fits its large eye and slender build, and FishBase places it at a trophic level of about 3.2, the level of a small predator on invertebrates. Within the Lake George community it is one of many haplochromines partitioning the available invertebrate prey; the lake's three dominant open-water fishes are algae-grazers feeding directly on the blue-green bloom, leaving the insect-larva niche to species like this one.
Mating
No courtship or social behaviour has been described for Haplochromis macropsoides specifically. Like the rest of the Lake Edward and Lake Victoria haplochromine flock, it is a maternal mouthbrooder, and the mating system of that group is well understood in general terms: males are the showier sex and, when ripe, defend a small spawning territory or display site and court passing females, advertising with their nuptial colours and with the egg-spots on the anal fin. Females visit, spawn, and then leave to brood the clutch alone. Pair bonds are not formed — a male may spawn with several females — and there is no paternal care. The specifics of where this species sets up to spawn, and whether males build any kind of nest depression, are unrecorded.
Breeding
Breeding in the wild has not been documented in detail for this species; FishBase records only that reproduction is by 'mouthbrooding by females', the universal pattern of its flock. By extension from its many well-studied relatives, the expected cycle is this: the female takes the freshly laid eggs into her mouth, where the celebrated egg-spot mechanism aids fertilisation — she snaps at the male's anal-fin ocelli, drawing his milt over the eggs already in her buccal cavity. She then carries the developing eggs and larvae in her mouth for roughly two to three weeks, not feeding while she broods, and releases free-swimming fry that may continue to dart back into her mouth for shelter for a short period afterward. Clutch sizes in small haplochromines of this body size are modest — typically on the order of a few dozen eggs (commonly around 20–60 in congeners of similar size) — but no count specific to Haplochromis macropsoides has been published, so that figure is a genus-typical estimate rather than a measured value.
In the aquarium
Haplochromis macropsoides is essentially never kept in the aquarium. It is a small, plainly coloured, scientifically obscure fish that has no presence in the ornamental trade — unlike the brightly coloured Lake Victoria 'Haplochromis' (such as the hobby's 'ruby green', Haplochromis sp. 'flameback' and similar) that conservation breeders maintain, this Lake George species is known almost entirely from museum collections and is documented as being hard even for specialists to distinguish from its neighbours in the field. There is no body of hobbyist husbandry experience to draw on. If a population ever did enter the hobby, the care template would be that of the small East African haplochromines generally: a maternal mouthbrooder that does best in hard, alkaline water (pH on the basic side, roughly 7.5–9, matching its warm, alkaline native lakes at around 75–82 °F), kept in a group with more females than males so that the attention of breeding males is spread out, with sand substrate, some rockwork or plant cover for refuge, and a varied diet emphasising small invertebrate and insect-based foods to suit its natural insectivory. For now, though, this is a wild species to read about rather than to keep.
Conservation
The IUCN Red List assesses Haplochromis macropsoides as Least Concern (assessed 2006 by T.K. Twongo; population trend unknown), reflecting that it is not currently known to be at risk despite its restricted range in the Lake Edward system. It carries no CITES or CMS listing. That said, the broader picture for the haplochromine flocks of the East African great lakes is sobering: the closely related Lake Victoria flock suffered catastrophic losses after the introduction of the Nile perch and the lake's eutrophication, and the Lake Edward–George system faces its own pressures, including dense infestations of invasive water hyacinth across Lakes Edward and George and the Kazinga Channel, alongside fishing pressure and nutrient loading. Because this species is genuinely difficult to identify and poorly monitored in the field, its true status is hard to track; the Least Concern listing should be read as 'no documented evidence of decline' rather than as a guarantee of security for a narrow-range endemic in a stressed basin.