Taxonomy & naming
Labidochromis mylodon was described in 1982 by Digby S. C. Lewis in his revision of the genus Labidochromis, published in the Zoological Journal of the Linnean Society (volume 75, number 3). The genus Labidochromis was established by Ethelwynn Trewavas in 1935 for small Lake Malawi cichlids defined by a forceps-like feeding apparatus — slender, well-spaced teeth at the jaw front, suited to picking small animals out of the algal film on rocks. The genus name joins Greek 'labis' (a pair of forceps) and 'chromis' (an old name for a perch-like fish). The epithet mylodon means 'molar tooth' or 'millstone tooth,' from Greek 'myle' (a mill or molar) and 'odous' (tooth), referring to the comparatively stout, robust teeth that distinguish this species from the more delicately toothed members of the genus — a small but telling departure from the typical Labidochromis dentition. The holotype (BMNH 1981.1.9.68) and paratype series, held at the Natural History Museum in London and other collections, were taken on the shore of Mumbo Island at about 14°00′S, 34°45′E, in the southwestern arm of Lake Malawi near Cape Maclear. The species belongs to the Cichlidae, subfamily Pseudocrenilabrinae, within the endemic mbuna radiation.
Morphology
Labidochromis mylodon is a small mbuna reaching about 3.5 in in total length (FishBase), making it one of the larger-bodied members of an otherwise small genus. It has the general Labidochromis form — an elongate, moderately compressed body, a fairly pointed head and a small, narrow mouth — but its diagnostic feature is in the teeth: as its name advertises, the dentition is comparatively stout and robust, less of a fine pincer than the slender 'forceps' of its congeners, which Lewis used as a key distinction. As in other mbuna, the species is sexually dichromatic, with dominant males more strongly coloured and patterned and bearing the usual ocellated egg-spots on the anal fin, while females and subordinate males remain plainer. Colour in life follows the generally subdued, barred pattern of many of the lake's smaller Labidochromis rather than a bold solid hue. Published morphometric detail beyond the original description is sparse.
Habitat
The species is endemic to Lake Malawi — the great rift-valley lake shared by Malawi, Mozambique and Tanzania — and within it is known only from the waters around Mumbo Island, a small rocky island in the southwestern arm near Cape Maclear (within the Lake Malawi National Park area). It is a fish of the mbuna zone, the boulder-strewn rocky littoral that is home to the lake's small rock-cichlids, typically in relatively shallow water within roughly the upper one to twenty metres. The water is the warm, hard, alkaline water characteristic of the lake — broadly 75–82 °F with a pH well above neutral and substantial carbonate hardness. As with other Labidochromis, the fish depends on the rock matrix and its coating of algal 'Aufwuchs,' which provides cover and harbours the invertebrate prey it picks at. Its apparent confinement to a single small island makes it one of the most narrowly distributed species in a genus already noted for tight, reef-bound ranges.
Feeding
Even with its stouter teeth, Labidochromis mylodon is, by the biology of its genus, a small invertebrate-picker rather than a dedicated algae-grazer. Labidochromis use their specialised front dentition to tweeze tiny animals — insect larvae, micro-crustaceans, mites and other meiofauna — out of the algal turf on the rocks, ingesting some algae and detritus incidentally; the heavier teeth of this species may reflect a slightly different mechanical emphasis but keep it within the genus's micro-predatory mode. FishBase assigns the species an estimated trophic level of about 2.7, in line with a small invertebrate-leaning omnivore. No species-specific gut-content study has been published for Labidochromis mylodon, so its diet is inferred from the consistent feeding ecology of the genus and from the structure of the Malawi rock community, where Labidochromis fill the niche of small invertebrate-pickers among many more herbivorous mbuna.
Mating
Like other mbuna, Labidochromis mylodon is a polygynous maternal mouthbrooder, though its courtship has not been described in detail. The genus follows the standard haplochromine pattern: a dominant male holds and defends a small rocky territory, intensifies in colour, and courts females with quivering lateral displays and circling. Spawning runs through the familiar egg-and-anal-spot sequence — the female lays a few eggs, immediately takes them into her mouth, then nips at the egg-spots on the male's anal fin to draw in milt and fertilise the clutch she already holds. There is no pair bond and no paternal care, and a single male may spawn with several females across a season. Sexual dimorphism is the usual mbuna arrangement of brighter, egg-spotted males and plainer females.
Breeding
Breeding details specific to Labidochromis mylodon are not documented, but follow with confidence from the genus and from Malawi mbuna in general. It is a maternal mouthbrooder: after spawning, the female alone incubates the fertilised eggs in her buccal cavity for roughly three weeks, fasting while the eggs hatch and the larvae develop on their yolk, then releases fully formed, free-swimming fry able to feed at once. Clutch sizes in small Labidochromis are modest — typically on the order of ten to thirty eggs, scaling with body size — and for a short time after release the female may continue to take the fry back into her mouth when threatened. This low-fecundity, high-investment strategy is shared across the rock-dwelling mbuna; the exact clutch size and developmental timing for Labidochromis mylodon itself remain unrecorded in the literature.
In the aquarium
Labidochromis mylodon is rarely seen in the hobby and is far less established than the ubiquitous yellow lab; as a single-island endemic it seldom enters the trade, and most aquarium 'labs' are Labidochromis caeruleus or its variants. Where it is kept, its needs are those of a typical small-to-medium mbuna. It requires the hard, alkaline, warm water of its home lake — a pH comfortably above 7.5, moderate-to-high hardness and a temperature around 75–81 °F — kept clean and well filtered, since rift-lake fish need oxygen-rich, stable, low-nitrate conditions.
The tank should be aquascaped with generous rockwork and caves over a sand bottom, giving territories and broken sight-lines. As a moderately assertive mbuna of reasonable size for the genus, it is best kept with other similarly sized rock-cichlids of comparable temperament, with enough rock to let territorial males spread out. Diet should follow the genus's invertivore leaning — quality flake or pellet plus small frozen and live invertebrates — rather than the very heavy algae regime sometimes pushed for strictly herbivorous mbuna. Honestly, this is a species better known to ichthyology than to aquarists: an interesting, robust-toothed Labidochromis that would suit an experienced Malawi keeper if obtained, but one that is essentially a specialist's fish rather than a hobby staple.
Conservation
Labidochromis mylodon was assessed by the IUCN as Least Concern in 2018. The status reflects that, although the species is restricted to the rocky habitat around Mumbo Island, that habitat is not at present subject to severe localised threat — Mumbo lies within the Cape Maclear area associated with Lake Malawi National Park — and the fish faces no major fishery pressure beyond incidental collection. The broader picture for Lake Malawi's narrow-range rock endemics remains cautious: the lake is under growing pressure from catchment deforestation and the siltation it brings, from intensive artisanal fishing, from shoreline development and from the longer-term effects of climate-driven warming and lake-level change. These pressures bear most heavily on mbuna whose populations are naturally fragmented island to island, and a species apparently confined to a single small island is intrinsically sensitive to any local degradation of its reefs. Labidochromis mylodon is therefore not of immediate conservation concern, but it is a clear example of a micro-endemic whose long-term security rests on the overall health of Lake Malawi's rocky littoral and the protection of its core localities.