Taxonomy & naming
Fundulopanchax marmoratus was described by the Austrian ichthyologist Arthur C. Radda in 1971. Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & Fong) records the valid combination as Fundulopanchax marmoratus (Radda, 1971), placing the species in the genus Fundulopanchax within the family Nothobranchiidae — the West and Central African killifishes. The parenthetical authority indicates that Radda did not originally assign the species to Fundulopanchax.
The specific epithet marmoratus is Latin for 'marbled', a direct allusion to the intricate patterning of the male's flanks — an overlapping mosaic of blue and red that in living specimens resembles veined stone or inlaid tilework rather than any simple banding or spotting arrangement. The common name Marbled Lyretail reflects both this pattern and the extended, lyre-shaped finnage of fully developed males.
Morphology
Adults reach a maximum total length of around 2.5 in, with males slightly larger and more elongated than females. Males are among the more striking West African killies in the genus: the body ground colour is dark olive to olive-brown on the upper flanks shading to a pale belly, overlaid with a dense, overlapping pattern of metallic blue and red scales that intensify toward the mid-flank. The pelvic fins are yellow to butter-coloured, and both the dorsal fin and pelvic fins carry white tips. The overall fin silhouette in fully conditioned males creates the lyretail impression that gives rise to the hobby common name.
Females are substantially drabber — a plain brownish body with darker scale edges and two short rows of reddish spotting immediately behind the gill cover on each flank. The sexual dimorphism is pronounced enough that sexing fish at a glance is straightforward, which is useful when managing breeding groups.
Habitat
Fundulopanchax marmoratus is known from the Mbonge area of southwestern Cameroon, with collection localities documented at Bakossi Camp (vouchers ADL 13/37 and CGVPM 15/2), Korup National Park, Mundemba, and several other rainforest sites (CMM 50, GS 1, GS 88/01). The American Killifish Association records eleven location records, all in Cameroon at high confidence. Some historical records reference Santa Isabella, a colonial-era name for Malabo on Bioko Island, though the species' core range is understood to be the mainland coastal lowlands.
The habitat is characteristic of West African forest killifish: swamps, swampy brooks, and slow-moving forest streams in the coastal rainforest belt. The water is typically soft, slightly acidic, and heavily stained with tannins leached from leaf litter and woody debris. FishBase records the water chemistry parameters as pH 6.0–7.0, hardness 5–12 dH, and temperature 70–73 °F — mild tropical lowland conditions consistent with the understorey forest floor where seasonal variation is dampened by the canopy.
Feeding
Like most Fundulopanchax, F. marmoratus is an insectivorous predator in the wild, feeding on small aquatic invertebrates — chironomid larvae, small crustaceans, and insect prey items that fall onto or develop within the forest-pool microhabitat.
In the aquarium the fish accepts a wide range of prepared and live foods. Live or frozen Daphnia, Artemia nauplii, bloodworm, and small chironomid larvae are all readily taken and support the best coloration. Finely milled dry foods are accepted by most captive populations. Variety is preferable to reliance on a single food type; alternating live and frozen meaty foods with a good-quality flake or micro-pellet keeps fish in condition without overloading any single nutrient pathway.
Mating
Fundulopanchax marmoratus is a semi-annual killifish — it is not a strict seasonal annual and its eggs do not require a mandatory dry incubation in the manner of the South American annual genera. In the field, the water table in coastal forest swamps can fall seasonally, and the eggs tolerate a period of damp incubation in leaf litter or soft substrate, but reproduction is not tied to a complete dry-season diapause cycle.
Males court females through lateral displays that showcase the blue-red flanking and yellow pelvic fins. In breeding condition males intensify in colour and pursue females persistently. The mating system is polygamous; a single male will court and spawn with multiple females in a community setting, and groups consisting of one male to two or three females are the practical unit for captive breeding.
Breeding
Spawning takes place at or among fine-leaved plants, Java moss, or peat fibre — the female releases a small number of adhesive eggs that the pair press into the substrate or plant material during brief spawning embraces. Eggs hatch in approximately one month at typical temperatures according to FishBase; hobbyist experience (including documented aquarium breeding) records hatch times of two to three weeks depending on temperature, with the lower end typical in warmer set-ups around 73–75 °F.
Fry are small at hatching and should be started on infusoria or paramecium cultures before graduating to freshly hatched Artemia nauplii, microworms, or vinegar eels. Young fish grow steadily and can reach sexual maturity within four to five months. Because F. marmoratus is non-annual, eggs can be incubated in water on spawning mops or peat, and the short incubation period simplifies rearing compared with annual species that require weeks or months of dry incubation. Maintaining eggs on damp but not submerged peat is also viable if water incubation batches prove troublesome.
In the aquarium
Fundulopanchax marmoratus suits a small, well-planted aquarium of 10–15 US gal or more for a breeding trio. The tank should be tightly covered — killifish are accomplished jumpers and F. marmoratus is no exception. Soft, slightly acidic water in the pH 6.0–7.0 range at 68–75 °F replicates natural conditions well; the species is reportedly adaptable outside these bounds in captivity, but extremes of hardness and pH should be avoided. Tannin addition via Indian almond leaves or driftwood is beneficial and visually appropriate.
The fish is peaceful with species of comparable size and temperament. A species tank or a community of similarly sized West African killifish and small tetras is ideal. Males can be mildly aggressive toward one another if space is limited; visual breaks — floating plants, clumps of moss, low driftwood — reduce inter-male conflict. The species is listed in the American Killifish Association studbook system and hobbyists interested in acquiring fish should consult AKA member lists, as it is infrequently available in the general trade.
This is a killifish for the dedicated enthusiast rather than the general aquarist: its husbandry requirements are modest, but access to fish, understanding of its semi-annual reproductive biology, and willingness to manage breeding groups appropriately are prerequisites for success.
Conservation
The IUCN Red List assesses Fundulopanchax marmoratus as Endangered under criteria B1ab(iii)+2ab(iii), assessed in 2009 by assessor T. Moelants. The criteria reflect a restricted extent of occurrence (B1) and area of occupancy (B2), combined with continuing decline in the quality and extent of habitat (iii — area, extent, and quality of habitat). The 2025-2 assessment version confirms the Endangered status remains current.
The primary threat is deforestation and degradation of the coastal rainforest of southwestern Cameroon. The Mbonge area and surrounding lowland forest zone have experienced significant logging, agriculture conversion, and infrastructure development. Swamp and forest-pool habitats that support the species are directly affected by drainage, siltation, and chemical contamination from adjacent agriculture. Korup National Park, within whose boundaries some populations occur, provides a degree of protection, but populations outside the park boundary face ongoing pressure.
The species' very restricted range makes it vulnerable to local extinction events. Hobbyist conservation through captive breeding has historically been one safety net for narrowly endemic West African killies, and the AKA's documentation of collection localities and maintenance of studbook data for this species represents a meaningful contribution to ex situ awareness. Formal in situ monitoring of habitat condition in the Mbonge area and populations within and around Korup remains important.