Taxonomy & naming
Mylochromis epichorialis was described in 1935 by the British ichthyologist Ethelwynn Trewavas, in her landmark 'A synopsis of the cichlid fishes of Lake Nyasa,' published in the Annals and Magazine of Natural History. She placed it originally in the sprawling catch-all genus Haplochromis, as Haplochromis epichorialis, with the type material taken from Deep Bay (modern Chilumba) at the northern end of the lake; the lectotype, held at the Natural History Museum in London (BMNH 1935.6.14.2426), was later designated by Eccles and Trewavas in their 1989 review of the Malawian haplochromine genera. That review moved the species into Maravichromis, a genus Eccles and Trewavas erected for elongate, sand- and rock-margin sediment-sifters; subsequent workers, following Konings and others, treat Maravichromis as a junior synonym of Mylochromis Regan, 1920, which is the name in current use and the one accepted by Eschmeyer's Catalog of Fishes. The genus Mylochromis is a large and somewhat heterogeneous assemblage within the Malawi haplochromine radiation, united by a generalised body plan and a habit of foraging at the interface of sand and rock. The Catalog of Fishes lists the species as valid as Mylochromis epichorialis (Trewavas, 1935), the authorship retained in parentheses because the species was first named in a different genus.
Morphology
Mylochromis epichorialis is a moderately elongate, laterally compressed cichlid reaching a maximum of about 8 in total length, making it one of the larger members of its genus. The body follows the generalised Mylochromis plan: a fusiform, gently tapering shape with a pointed snout, a relatively small inferior-to-terminal mouth suited to sifting and picking from the substrate, and a continuous dorsal fin. As is typical for Lake Malawi haplochromines, breeding males develop the brightest coloration and bear egg-spots (ocelli) on the anal fin, while females and non-breeding fish are more subdued and silvery. Detailed published meristics specific to this species are sparse compared with the better-studied mbuna, but the genus is characterised by a single, complete-to-interrupted lateral line system, bicuspid and tricuspid jaw teeth arranged for grazing and sifting, and the pharyngeal mill common to all cichlids. Coloration and precise fin-ray counts vary geographically across the lake, and as with many Malawi haps the living animal is more distinctive than the preserved specimen.
Habitat
The species is endemic to Lake Malawi (historically Lake Nyasa), the second-deepest and one of the most species-rich lakes on Earth, lying within the East African Rift. FishBase records it from both the southern and the northern ends of the lake, with the type locality at Deep Bay (Chilumba) in the north; this two-ended distribution across hundreds of kilometres is unusual among Malawi cichlids, many of which are confined to a single stretch of shore. It is a demersal fish found over rocks and at the sand-rock interface, recorded from the surface down to at least 98 ft. Its waters are the warm, hard, alkaline waters characteristic of the lake as a whole: temperatures generally around 75–79 °F in the upper layers and a stable, high pH of roughly 8.0–8.5, with substantial dissolved-mineral content. Like the rest of the Malawi assemblage it lives in a strongly stratified lake whose deep water is permanently anoxic, so the fish are restricted to the oxygenated upper few tens of metres along the coast.
Feeding
Mylochromis epichorialis is a benthic foraging predator that works the substrate rather than the open water. Observations summarised by FishBase note it consuming crabs and feeding from sediment on rocks, and it is placed at a trophic level of about 3.5 — squarely in the range of a carnivore that takes invertebrates and small prey rather than a dedicated algae-grazer. This fits the broader ecology of Mylochromis, whose members are generally invertebrate-feeders and sediment-sifters that pick through sand and detritus at the margins of rocky outcrops, extracting insect larvae, small crustaceans, molluscs and other benthic animals. The pointed snout and sifting mouth are the tools of this trade: the fish takes mouthfuls of sediment and sorts edible items with its gill rakers and pharyngeal jaws. As a relatively large hap, it can also take larger hard-shelled prey such as the crabs noted above, pointing to robust pharyngeal teeth capable of crushing.
Mating
No detailed courtship study has been published for Mylochromis epichorialis specifically, but its reproductive behaviour can be inferred with confidence from the consistent biology of the Malawi haplochromine flock to which it belongs. These cichlids are polygynous maternal mouthbrooders with no pair bond: males establish and defend temporary territories during the breeding season, often over or beside the substrate, and develop intensified nuptial coloration to court passing females. A receptive female is led to the spawning site, where the male displays and quivers; the characteristic egg-spots on his anal fin are thought to play a role in the spawning sequence, encouraging the female to snap at them and so draw milt into her mouth as she collects the eggs. Males of this and related species do not contribute to brood care, instead continuing to court additional females, so reproductive success is skewed toward the most successful territory-holders.
Breeding
Like essentially all Lake Malawi haplochromines, Mylochromis epichorialis is a maternal mouthbrooder. After spawning, the female carries the fertilised eggs and then the developing larvae in her buccal cavity, where they are protected and aerated until they reach the free-swimming fry stage; she does not feed, or feeds very little, during this period of several weeks. Clutch sizes in comparable medium-to-large Malawi haps typically run from a few dozen to around a hundred eggs, scaling with female size, though no clutch count has been published specifically for this species. The fry are released once developed and may briefly return to the mother's mouth when threatened, after which they are independent. There is no published aquarium breeding record specific to Mylochromis epichorialis, and the account given here is drawn from the well-documented and highly uniform breeding biology of the Malawi mouthbrooding radiation rather than from direct observation of this species.
In the aquarium
Mylochromis epichorialis is not a staple of the aquarium hobby and is only occasionally encountered, usually among specialist keepers of Malawi haplochromines rather than in the general trade. Any husbandry guidance is therefore extrapolated from the requirements of similarly sized Malawi haps and from the species' known habitat.
At roughly 8 in it is a substantial fish that needs a large tank — on the order of a metre and a half or more in length — with a sandy bottom it can sift, scattered rockwork to break up sightlines, and plenty of open swimming space. The water should reflect the lake: hard, alkaline (pH around 8), and warm (mid-20s Celsius), kept clean and well-oxygenated by strong filtration, since these fish come from a stable, high-quality environment and are sensitive to accumulated nitrogenous waste and the bloat that afflicts overfed or poorly kept Malawi cichlids. A varied carnivore-leaning diet of quality pellets, frozen invertebrates and similar fare suits its natural feeding habits; excessive high-protein or mammalian-fat foods should be avoided. As with most haps, it is best kept with robust Malawi tankmates of comparable size and one male to several females to spread out breeding aggression. This is a fish for the dedicated Rift-lake hobbyist rather than the casual community keeper.
Conservation
Mylochromis epichorialis was assessed by the IUCN Red List as Least Concern in 2018. That comparatively reassuring status rests on its broad distribution across both the northern and southern ends of Lake Malawi, which gives it a far larger range than the many point-endemic mbuna confined to single reefs. It is recorded as being of some interest to both commercial fisheries and the aquarium trade, but neither appears to threaten the species at present. The broader context is less comfortable: Lake Malawi as a whole faces mounting pressure from heavy artisanal and commercial fishing, sedimentation and nutrient runoff from a growing lakeshore population, deforestation in the catchment and the looming effects of climate change on the lake's stratification and oxygenated habitat — concerns documented across the conservation literature on the lake's extraordinary but vulnerable cichlid fauna. For a wide-ranging generalist such as Mylochromis epichorialis these are background risks rather than immediate ones, which is why its current listing remains Least Concern.