Taxonomy & naming
Scriptaphyosemion roloffi was first described in 1936 by Erhard Roloff, the German amateur ichthyologist and aquarist after whom the species is named, and the authority is therefore given as (Roloff, 1936). Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & Fong) recognises the valid combination as Scriptaphyosemion roloffi. The genus Scriptaphyosemion belongs to the family Nothobranchiidae, the African killifishes, and groups together a set of small, non-annual West and Central African species that share a preference for forest pools and permanent or near-permanent small waters.
The species has been known under various generic placements as killifish taxonomy has been revised over the decades, but the current Scriptaphyosemion allocation reflects molecular and morphological work that distinguishes this clade from the superficially similar Aphyosemion and Fundulopanchax clades. Two colour-pattern variants are recognised in the hobby — an eastern population and a western variant formerly coded RSL29 in British Killifish Association (BKA) records, sometimes referred to as the Hastingsi variant — though these are not formally described subspecies.
The specific epithet roloffi honours Erhard Roloff (1903–1980), who collected and described the species and contributed substantially to knowledge of West African killies through fieldwork and aquarium observation.
Morphology
Adults reach approximately 2 in total length (FishBase), making this a small but attractively marked species. The body plan is typical of the genus: slender and moderately compressed, with a dorsally placed dorsal fin and a rounded caudal fin characteristic of non-annual killifishes. Sexual dimorphism is pronounced. Males of the eastern population display an olive-green dorsum with blue highlights on the flanks, a reddish head, and flanks that transition from light brick-red to a deeper brick or brownish red toward the rear, overlaid with scarlet spots; the caudal region takes on a dark-blue cast with scarlet spotting. Males of the Hastingsi variant show an olive-green back with a red mosaic across the flanks. Both males reach approximately 2 in; females of both variants are slightly smaller, around 2 in, and considerably plainer — a brown to olive-tan body with reduced or absent red and blue ornamentation, though the pattern of spots remains discernible.
The finnage of males is well developed and contributes substantially to their display. Females are rounder-bodied when gravid, which, combined with their more muted colouration, makes sex identification straightforward at around four months of age, when the males' caudal margins begin to darken noticeably.
Habitat
Scriptaphyosemion roloffi occurs in the Little Scarcies River drainage of western Sierra Leone east to the Lower Lofa River drainage of western Liberia — a coastal rainforest belt with an extent of occurrence of approximately 86,303 mi² according to the IUCN assessment. Within this range it inhabits the shallow stagnant sections of forest pools, swampy hollows, slow-running brooks, and small streams rather than main-channel rivers. FishBase describes the species as benthopelagic, non-migratory, and restricted to freshwater.
The waters it occupies are characteristically soft, tannin-stained, and gently acid: FishBase records a temperature range of 72–75 °F, a pH of 6.3–7.0, and hardness of 1–6 dH. The British Killifish Association's keeper experience in aquaria aligns closely, recommending pH 6.4–6.8 and 2–7 German degrees of hardness. Dissolved oxygen is likely variable in the stagnant pools the species favours, which would explain its tolerance of still, shaded water with a thin litter of leaves and debris on the bottom — conditions typical of West African forest lowland killifish habitats.
Unlike many members of the wider killifish order, this species is not a seasonal fish: the pools and brooks it inhabits persist year-round, so the population does not rely on diapausing eggs to bridge a dry season. Its ecology is therefore more analogous to small tetras or rasboras in the same forest zones than to the annual killifish of seasonal savanna pans.
Feeding
In the wild Scriptaphyosemion roloffi forages in the lower and middle water column of shallow forest pools, preying on small aquatic invertebrates — water fleas, mosquito larvae, chironomid midges, micro-crustaceans — and any small insect that falls to the water surface. The forest-pool setting provides a seasonally rich invertebrate supply tied to leaf litter decomposition and rainfall.
In aquaria the species adapts without difficulty to live and frozen foods: Daphnia, Artemia nauplii and adults, bloodworm (Chironomus larvae), white mosquito larvae, and similar items are all accepted readily. Dried foods are taken by some individuals but are best offered as a minor supplement to a primarily live or frozen diet to maintain full colouration and breeding condition. Because this is a small fish, all food items should be appropriately sized — finely chopped or small-particle offerings work best. Overfeeding in a small, softly filtered killifish setup will degrade water quality quickly; little and often is a better feeding regime than large infrequent meals.
Mating
Scriptaphyosemion roloffi is a non-annual killifish and a plant or mop spawner: pairs deposit small adhesive eggs on floating spawning mops, peat-fibre carpeting, fine-leaved plants, or surface vegetation over an extended period rather than engaging in a single mass spawning event followed by egg burial. This mode of reproduction is tied directly to the species' habitat in permanent or near-permanent water, where no dormancy phase is required to survive seasonal drought.
Male courtship involves lateral display with erect, fanned fins, showing off the full pattern of red spots and blue iridescence. The male approaches from the side or below, and a brief side-by-side position against the spawning mop precedes each egg deposition. A small number of eggs — typically just one to a few — are released per approach. Spawning continues intermittently over days and weeks rather than being concentrated in a single session. Males are generally not excessively aggressive toward one another by killifish standards, but in a confined space a single male to one or two females is the practical setup.
Breeding
Eggs are very small and adhere to the fibres of a floating mop or the leaves of fine-leaved plants. Unlike annual killifish eggs, they do not require a drying-out phase in peat or sand: they incubate continuously in water at temperatures around 72–75 °F. The British Killifish Association records a hatching time of approximately 16–18 days under these conditions. The fry are extremely small on emergence — among the smallest of any commonly kept killifish — and require infusoria or liquid fry food for at least the first week before they can accept newly hatched Artemia nauplii.
Best results are obtained by leaving fry with the parents for the first two weeks, then transferring the fry to a separate rearing vessel. Growth is slow relative to many other small fish: males begin to show darkening of the caudal margins at around four months, but full sexual maturity is not reached until approximately 10–12 months of age. This extended development period is consistent with the species' non-annual life history and its comparatively long lifespan relative to seasonal killifish.
Spawning mops should be checked and eggs removed to a small hatching container every one to two weeks to prevent predation. A dark-bottomed, dimly lit, well-planted or mop-furnished rearing tank with gentle sponge filtration and regular small water changes best supports the long development of fry to juvenile.
In the aquarium
Roloff's killifish is a challenging species by general aquarium standards and is best regarded as a fish for dedicated killifish keepers rather than community tanks. Its requirements for very soft, gently acid water (pH 6.4–6.8, 2–7 dH, 72–75 °F) are non-negotiable for long-term health and breeding success; the species does not thrive in neutral or moderately hard tap water without significant conditioning. Reverse-osmosis water remineralised to the correct hardness is the standard approach among specialist keepers.
The tank should be small to medium — a 10–15 US gal setup for a pair or trio is adequate — with subdued lighting, a dark substrate, dense plant cover or mops both at the surface and near the bottom, and a tightly fitting lid. Floating plants such as Indian fern (Ceratopteris) or water sprite complement the species' preference for shaded, vegetated surface zones. A mature, lightly loaded sponge filter provides gentle flow without creating the turbulent, oxygenated conditions the species does not seek in nature.
Tankmates, if used at all, should be restricted to similarly sized, soft-water-adapted species with no inclination to nip fins. Most keepers maintain this species as a single-species setup or with small, peaceful companions such as microdevario or small rasboras. The BKA notes that males are not excessively combative, making a single-male, multi-female group a viable and attractive display. The Hastingsi and eastern colour variants should not be kept together if pure lines are to be maintained.
Conservation
The IUCN Red List assessed Scriptaphyosemion roloffi as Least Concern (LC) in 2020, an upgrade from the Near Threatened (NT) status assigned in 2010. The species' extent of occurrence across the Sierra Leone–Liberia border region is approximately 86,303 mi², and it occupies a variety of wetland habitats — permanent rivers, streams, marshes, bogs, and swamps — within that range. Population trend is recorded as unknown.
Despite the LC designation, the IUCN assessment flags several localised threats within the species' range, particularly in Liberia: artisanal and industrial mining activity, deforestation for agriculture and logging, and pollution of watercourses. Sierra Leone and Liberia both have histories of forest clearance in the coastal lowland zones that the species inhabits, reducing and fragmenting the pool, swamp, and brook habitats on which it depends. The species is collected for the international aquarium trade, which adds modest additional pressure but is not considered a primary threat at current collection levels.
The 2010 Near Threatened listing reflected concern about the degree of habitat loss in the region; the 2020 reassessment to LC suggests that surveyors found the species more widespread or resilient than previously thought, or that the rate of habitat loss had not translated into measurable population decline detectable within the assessment period. Ongoing monitoring in both Sierra Leone and Liberia would be valuable given continued land-use pressures in the Guinean Forest Biodiversity Hotspot, of which this species' range forms a part.