Taxonomy & naming
Myaka myaka was described by the British ichthyologist Ethelwynn Trewavas in 1972, in the landmark monograph 'Ecological studies on crater lakes in West Cameroon: Fishes of Barombi Mbo' (Journal of Zoology, London, volume 167, pages 41–95), co-authored with the limnologists James Green and Sarah Corbet. Trewavas erected the new genus Myaka to receive it, and in the half-century since, no second species has ever been added — Myaka remains monotypic, a lineage of one. The holotype (BMNH 1971.10.20.34) and a series of fifteen paratypes are held at the Natural History Museum in London. The name is unusual in that genus and species are the same word twice over: Trewavas split the local Barombi vernacular name for the fish, 'myakamyaka', into 'Myaka' for the genus and 'myaka' for the species. The myaka belongs to the African subfamily Pseudocrenilabrinae and, within it, to the tilapiine assemblage (the Oreochromini in current usage). Genetic work has since shown that the entire Barombi Mbo cichlid radiation — the genera Myaka, Konia, Pungu, Stomatepia and the lake's endemic Sarotherodon — forms a single monophyletic lineage descended from a riverine ancestor close to Sarotherodon galilaeus, an in-situ adaptive radiation that diversified inside the crater after the lake formed. The myaka represents the planktivorous, open-water specialist of that flock.
Morphology
The myaka is a small fish, reaching about 2.5 in in standard length — among the smallest of the Barombi Mbo endemics, though aquarium and field reports of larger individuals (to roughly 4.5–5.5 in total length) circulate among hobbyists. The body is fusiform and slender, a streamlined open-water shape that suits a fish that spends its life suspended in midwater rather than working a substrate. The single most diagnostic external feature is the mouth: it is strongly upturned, set at an angle of about 50 degrees to the horizontal, the hallmark of a fish that feeds on items drifting above and ahead of it. The dentition is reduced to match a planktonic, soft-debris diet — the outer row of jaw teeth is sparse and feeble, the inner rows minute and tricuspid. Internally the lower pharyngeal jaw is distinctive and gives the genus its diagnosis: it is markedly longer than wide, with a reduced dentigerous surface covered by a dense 'felt' of tiny unicuspid teeth, an apparatus for handling fine, soft food rather than crushing hard prey. Meristics run to 14–15 dorsal spines and 10–12 soft dorsal rays, 3 anal spines with 8–10 soft anal rays, and 28–29 vertebrae. Breeding males assume a darker, more contrasting dominant coloration; outside of that, the species is a fairly plain silvery fish, its drama hidden in the geometry of its jaws.
Habitat
Myaka myaka is endemic to Lake Barombi Mbo and occurs in no other body of water. Barombi Mbo is a maar — a volcanic crater lake on the Cameroon Volcanic Line, roughly circular, about 2 mi across, sitting near 984 ft above sea level some 37 mi from Mount Cameroon. It is deep for its size, reaching about 361–364 ft, with a mean depth near 226 ft, and at least a million years old, old enough for its isolated cichlids to have radiated in place. The lake is permanently stratified: dissolved oxygen effectively disappears below about 66–98 ft, so the great anoxic deep is uninhabitable and the fish are confined to the upper, oxygenated layer and the open water above the dead zone. Surface water is warm, soft and circumneutral — field measurements of the lake surface give temperatures around 81–82 °F and pH near 7.0–7.9 (inflowing streams run cooler and slightly more alkaline), with low conductivity characteristic of fresh water; the deep water is colder, more acidic and bicarbonate-rich. The myaka is the open-water specialist of the flock, favouring the offshore regions over greater depths and venturing into shallower water mainly to spawn. Within the Freshwater Ecoregions of the World scheme the lake falls in the Western Equatorial Crater Lakes ecoregion, a cluster of Cameroonian crater lakes famous for their endemic cichlid species flocks.
Feeding
The myaka is a planktivore — the plankton-straining member of the Barombi Mbo flock. Its upturned mouth, reduced jaw teeth and felt-covered pharyngeal jaw all point to a diet of small, soft, suspended food, and the gut contents bear this out: stomachs contain very fine organic debris and phytoplankton, taken from suspension in the open water, supplemented by small insects. Trewavas and colleagues judged that the myaka probably feeds on dead phytoplankton and other organic debris drifting close to and above the bottom of the oxygenated zone, as well as straining living plankton from the column. Its estimated trophic level is low, around 2.6, consistent with a primary-consumer feeding on plant plankton and detritus rather than on other animals. Barombi Mbo is not a richly productive lake — vertical plankton hauls yield little, and much of the suspended material is too fine to be caught even by fine nets — so the myaka exploits a thin but reliable resource that the lake's substrate-bound and shell-crushing endemics largely ignore. In doing so it fills the pelagic, plankton-feeding niche that in larger African lakes is occupied by sardine-like fishes, a textbook case of an adaptive radiation partitioning a small lake among specialised feeders so that each species takes a different 'main course'.
Mating
Reproduction draws the myaka out of the open water and into the shallows. The species spends most of the year offshore over deeper water, but moves into shallower areas of the lake to breed, normally during the rainy season. There, males establish small territories — each roughly half a metre across — and these territorial males pack into restricted areas, so that large numbers of them can be found defending neighbouring patches in a small stretch of bottom, a loose lek-like aggregation. Males in breeding condition take on a darker, more contrasting dominant coloration to court passing females. As in its tilapiine relatives, the myaka is a mouthbrooder, and brood care falls to the female, so the male's role is concentrated in this territorial, courtship phase: holding a patch of spawning substrate, displaying, and competing with the dense cluster of rival males around him for the attention of ripe females moving through the shallows.
Breeding
Myaka myaka is a maternal mouthbrooder, and breeding is tied to the rainy-season migration into shallow water. After a female spawns with a territorial male, she takes the fertilised eggs into her mouth and broods them there through development, the standard reproductive strategy of the tilapiine cichlids to which the genus belongs; it is described as an ovophilic (egg-brooding) mouthbrooder. As with most small mouthbrooders, fecundity is modest — a mouthbrooding female can only carry as many eggs and larvae as will fit in her buccal cavity, so clutches in a fish of this size run to a few dozen rather than the hundreds laid by open-substrate spawners — though precise published egg counts for the myaka itself are scarce, and the figure is best read as genus-typical for a small mouthbrooding tilapiine rather than a measured value. The female provides all the parental care, sheltering eggs and then free-swimming fry inside her mouth and releasing them to forage once they are developed enough to fend for themselves. Spawning concentrated in the rainy season and in shallow water suggests the timing exploits warmer, more productive shallows for the vulnerable fry.
In the aquarium
Myaka myaka is very much a specialist's fish, not a community-tank cichlid, and it reaches hobbyists only rarely — almost always through dedicated keepers of the Barombi Mbo flock or scientific and conservation collections rather than the general trade. The Cichlid Room Companion rates it a fish for advanced aquarists, and that is the right framing: it is a shoaling, open-water planktivore with specific needs and limited captive history.
Because it is an active, midwater swimmer that naturally lives in loose aggregations of territorial males, it wants a long tank with plenty of open swimming room rather than a rockwork maze. Keepers who have maintained it describe restless, torpedo-like fish that chase one another constantly, so a group in a spacious aquarium — long footprint, generous volume — manages that energy far better than a small tank with a handful of fish, where a dominant individual can harass the rest. Water should mirror the lake: warm (about 75–86 °F), soft, and circumneutral to mildly alkaline (pH roughly 7.0–8.5), kept clean and well oxygenated. Good filtration and steady water changes matter, because these are fish of a large, stable water mass rather than a variable stream.
Feeding is the practical challenge. In the wild the myaka strains fine phytoplankton and organic particles, so a captive diet should lean on small, frequent feedings of fine-particle and plankton-type foods — small frozen items, finely crushed flake, and spirulina or other plant-based fare suit its low trophic level and upturned, plankton-straining mouth better than large meaty foods aimed at predatory cichlids. As a mouthbrooder it can be bred in captivity by experienced keepers, with females holding broods in the mouth, but it is not a casual project. The honest summary is that this is a conservation-relevant rarity to be kept by people equipped to do it properly — and, given its Critically Endangered status in the wild, captive populations in knowledgeable hands have genuine ark value.
Conservation
Myaka myaka is assessed by the IUCN Red List as Critically Endangered, under criteria B1ab(iii)+2ab(iii) (assessed 16 February 2009, published 2010, assessor T. Moelants). The category is driven not by documented collapse but by geography: the species' entire global range is a single small crater lake of about 2 mi², so any deterioration in the quality of that one habitat threatens the whole species at once, the classic situation of an extreme single-site endemic. The threats to Barombi Mbo are real and growing. The lake is the drinking-water source for the half-million-strong city of Kumba and sits within a heavily used watershed: water-quality studies document eutrophication and macroalgal blooms driven by nutrient runoff from surrounding cocoa farms and the lakeside village, together with sewage contamination. Sedimentation, deforestation of the crater rim, shoreline agriculture, fishing pressure and the introduction or arrival of non-native fishes all bear on the endemic flock. The lake is a designated Ramsar wetland and lies within a forest reserve, but on-the-ground protection is weak, and surveys note that anthropogenic activity has already compromised water quality inside the supposedly protected lake. For a fish that exists in this one body of water and nowhere else, the long-term security of Myaka myaka is inseparable from the conservation of Barombi Mbo as a whole.