Taxonomy & naming
Haplochromis turkanae was described by the British ichthyologist Peter Humphry Greenwood in 1974, in his revision 'The Haplochromis species (Pisces: Cichlidae) of Lake Rudolf, East Africa' (Bulletin of the British Museum (Natural History), Zoology 27(3): 141–165). The type locality is in Lake Rudolf (now Lake Turkana), Kenya — roughly 3–4 mi northwest of Porr, at about 52 ft depth. The epithet turkanae simply marks the lake to which the fish is endemic. Greenwood's monograph was the foundational study of the lake's haplochromine cichlids, recognising a small endemic assemblage — turkanae among them, alongside Haplochromis macconneli, Haplochromis rudolfianus and relatives. The species' generic placement reflects the long-running difficulty of the catch-all genus Haplochromis: it is carried as Haplochromis turkanae by FishBase and the Catalog of Fishes, but some workers assign the Turkana endemics to the genus Thoracochromis, so the combination Thoracochromis turkanae appears in parts of the literature. Both names denote the same fish; the broader haplochromine genus problem remains unresolved.
Morphology
Haplochromis turkanae is a small cichlid, reaching about 3.5 in standard length — among the larger of the lake's endemic haplochromines but still a modest fish. The body is the moderately deep, laterally compressed haplochromine form. As with most of Greenwood's Turkana species, live coloration is comparatively subdued by the standards of the rock-dwelling flocks of the other Rift lakes — a silvery to greyish-brown ground, fitting an offshore, often turbid environment where the gaudy display colours of shallow-water rock cichlids would be wasted. Diagnostic separation from its congeners in the lake rests on the meristic and osteological characters Greenwood used in his revision, including jaw and dental features tied to its specialised feeding. Sexual dimorphism follows the haplochromine pattern: breeding males develop more intense coloration and typically carry egg-spots (ocelli) on the anal fin, while females stay plainer; detailed dimorphism for this species is not separately tabulated beyond Greenwood's account.
Habitat
The species is endemic to Lake Turkana, a closed-basin, mildly saline, strongly alkaline desert lake on the floor of the Kenyan Rift, its northern end reaching into Ethiopia and fed chiefly by the Omo River. The lake is warm year-round (roughly 79–88 °F at the surface), highly alkaline (pH around 8.5–9.2), carbonate-rich and turbid with a jade-green cast. Haplochromis turkanae is an offshore, benthopelagic fish: its type material came from around 52 ft depth, and it lives over the lake's open bottoms rather than in the inshore shallows favoured by smaller relatives such as Haplochromis rudolfianus. In-situ water chemistry for the species specifically is not separately published, but it is that of the lake at large — warm, hard and alkaline.
Feeding
The most distinctive thing about Haplochromis turkanae is its diet. It is recorded as feeding on the shell fragments of ostracods — the discarded carapaces (and occupants) of these tiny bivalved crustaceans — which it grinds and processes, a trophic specialisation reflected in FishBase's estimated trophic level of about 3.5. This places it among the more specialised feeders of the Turkana flock, exploiting a food resource — ostracod shell material on and in the lake bed — that few other fish target. The specialisation is consistent with the way East African haplochromine radiations partition food: even a small endemic assemblage like Turkana's shows divergence in jaws and diet, with turkanae occupying a hard-prey/shell-processing niche.
Mating
No courtship or pre-spawning behaviour has been described specifically for Haplochromis turkanae; what can be said is inferred from its membership of the maternal-mouthbrooding haplochromine lineage, which is among the best-studied reproductive systems in fishes. In these cichlids males establish and defend a small territory or display site and court passing females with lateral displays and quivering, the anal-fin egg-spots playing a role in spawning. Females are the choosier, mobile sex. Whether turkanae males build or hold a particular spawning arena in Turkana's offshore habitat is undocumented; the species is too poorly studied in life for its mating system to be described in detail.
Breeding
Haplochromis turkanae is a maternal mouthbrooder, as recorded for the species and as is universal among the haplochromine cichlids to which it belongs. After spawning the female takes the fertilised eggs into her mouth and broods them there through hatching and the early free-swimming stage, releasing the fry only when they can fend for themselves and taking them back in at the first sign of danger. This makes for relatively small clutches of large, well-provisioned young — the standard haplochromine trade-off of fecundity for survivorship. Specific clutch sizes, brooding duration and fry development for turkanae have not been published; they are expected to fall within the normal haplochromine range (broadly tens of eggs, brooded for two to three weeks). The species is not known to have been bred or maintained in captivity.
In the aquarium
Haplochromis turkanae is essentially unknown in the aquarium hobby. Unlike the Turkana jewel cichlid (Rubricatochromis exsul), which is occasionally traded, this small offshore haplochromine is a scientific specimen rather than an aquarium fish: it is not collected for the trade, not commercially bred, and there is no body of keeping experience to report. Any husbandry advice would therefore be speculative. If it were ever maintained, the basic requirements would follow from its habitat — warm water around 75–82 °F, hard and strongly alkaline (pH well above 8), with the robust biological filtration and stable chemistry that hard-water Rift cichlids need, and a maternal-mouthbrooder's harem-style social management. The honest statement is that this fish has not been kept and there is no established protocol for doing so.
Conservation
The IUCN Red List assesses Haplochromis turkanae as Least Concern, assessed on 31 January 2006 (assessors Odhiambo & Hanssens), on the basis that it is distributed through Lake Turkana with no documented species-specific threat. As with all of the lake's endemics, that assessment must be read against the growing pressure on Lake Turkana itself. The lake is sustained almost entirely by the Omo River, and the chain of large hydroelectric dams (Gibe III and its successors) and large-scale irrigated plantations developed on the Omo in Ethiopia have reduced inflow and are projected to lower lake level and increase salinity over the coming decades. For a single-lake endemic, the long-term outlook is bound to the hydrological and ecological trajectory of Turkana as a whole rather than to any direct exploitation of the species.