Taxonomy & naming
Scriptaphyosemion bertholdi was described by the German killifish collector and author Erhard Roloff in 1965, based on specimens collected at Kenema, a town in the Eastern Province of Sierra Leone. The authority is written in parentheses — (Roloff, 1965) — indicating the species has been reassigned since its original description. Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & Fong) records the current valid combination as Scriptaphyosemion bertholdi (Roloff, 1965).
The genus Scriptaphyosemion, erected by Radda & Pürzl in 1987, groups a cluster of small, non-annual West African killifishes formerly placed within the broadly defined genus Aphyosemion. The genus is distributed from Guinea through Sierra Leone and Liberia into Côte d'Ivoire, and its species are characterised by a non-annual life strategy — they inhabit permanent or near-permanent forest streams rather than the ephemeral pools that constrain annual killifish — and by the male's typically elaborate reticulate or spotted colouration across the flanks and unpaired fins.
Morphological and molecular studies, referenced in the killifish literature and noted by sources including Seriously Fish, confirm S. bertholdi as a valid and diagnosable species distinct from congeners such as S. cauveti and S. guignardi. Distribution records place it in the coastal lowlands and hinterland forest streams of Sierra Leone and Liberia, within the Guinean Forest biodiversity hotspot.
Morphology
Scriptaphyosemion bertholdi is a small, slender killifish reaching approximately 2 in standard length in males; females are typically somewhat shorter and more cylindrical in build. The body is moderately laterally compressed, with the dorsal profile gently arched and the ventral surface nearly straight. As in other Scriptaphyosemion, the mouth is directed slightly upward, an adaptation for surface-oriented feeding.
Sexual dichromatism is strongly pronounced, as noted in the killifish literature and confirmed by Seriously Fish sources. Males display an intricate pattern of red-orange to reddish-violet spots and streaks overlaid on a greenish-olive to blue-grey ground colour, with the unpaired fins — dorsal, caudal, and anal — extending this coloration into elaborate, bordered patterns that become more vivid in dominant, conditioned fish. The caudal fin in males may show red edges with paler inner zones. Females are cryptically coloured, typically plain olive-brown or yellowish, with at most a faint speckling of dark pigment on the flanks; their fins are rounded and mostly clear.
Habitat
Scriptaphyosemion bertholdi occupies shallow forest streams and pools in the coastal lowland rainforest of Sierra Leone and Liberia — a landscape that forms part of the Upper Guinean section of the Guinean Forest Biodiversity Hotspot, one of the world's most species-rich and most threatened tropical forest blocks. FishBase records the species as occurring in shallow parts of pools and small streams within rainforest, preferring clear, flowing water in coastal lowlands.
The water in these habitats is typically soft and slightly to moderately acidic, stained lightly with tannins leaching from leaf litter and decaying wood. As a non-annual species inhabiting permanent or near-permanent water bodies, S. bertholdi does not depend on seasonal flooding and pool-drying cycles the way annual killifishes do; instead it persists in streams and pools that retain water year-round, where it encounters stable substrate, overhanging riparian vegetation, and submerged plant material that serves as spawning and refuge habitat. Natural water chemistry recorded by Roloff and referenced in AKA sources was typical of such forest streams: low pH, negligible hardness, and warm temperatures consistent with the lowland equatorial climate.
Feeding
Like other small Scriptaphyosemion, S. bertholdi is a micro-predator in its natural habitat, hunting the invertebrates that colonise the leaf-litter margins and water surface of forest streams. The diet in the wild is presumed to consist primarily of small aquatic and surface-fallen insects, larvae, microcrustaceans, and other zooplankton — the standard resource base for small killifishes inhabiting shaded, forest-stream environments where phytoplankton production is limited by the canopy.
In aquarium conditions the species accepts live and frozen invertebrate foods readily. Daphnia, Cyclops, bloodworm (Chironomus larvae), and Artemia nauplii are all taken with enthusiasm. Small dried foods may be accepted by settled fish. Feeding twice daily in modest amounts is appropriate; killifish of this size benefit from the variety and nutritional completeness of live or frozen prey over an exclusively dry-food diet.
Mating
Scriptaphyosemion bertholdi is a non-annual, plant-spawning killifish. Unlike annual killifishes that bury their eggs in the substrate and rely on a diapausing resting phase to survive dry seasons, S. bertholdi deposits adhesive eggs on fine-leaved aquatic plants, submerged roots, or fine-fibre spawning mops, with the eggs developing continuously in water without entering diapause. This reproductive strategy is documented for the genus by killifische.info and is consistent with the species' habitat in permanent forest streams where seasonal desiccation does not occur.
Spawning is pair-based and extended over time rather than a single mass-spawning event. A conditioned male courts a female with lateral displays that showcase his colouration; when receptive, the female joins the male alongside or among plant material, and the pair deposit one or a small number of adhesive eggs per embrace. This is repeated across multiple sessions over days or weeks. Because the eggs are adhesive, they cling to plant leaves or mop fibres and are less vulnerable to accidental disturbance than free-floating or substrate-buried eggs.
Breeding
In the aquarium, breeding is achieved by conditioning a pair or a small group (one male, two or more females) on live and frozen foods and providing fine-leaved plants such as Java moss (Taxiphyllum barbieri) or commercial nylon spawning mops as egg-deposition sites. Water should be soft and slightly acidic — matching the natural chemistry of Upper Guinean forest streams — at a temperature in the range of approximately 72–77 °F.
Eggs are collected every few days by removing the mop or plant material to a shallow hatching container with similar water. Unlike annual killifish eggs, which require a dry-storage phase, Scriptaphyosemion eggs are incubated directly in water and should not be dried. Hatching typically occurs within two to three weeks depending on temperature. Fry are small at hatching and require appropriately sized first foods: infusoria, micro-worms, or newly hatched Artemia nauplii. Growth is steady at the temperatures noted, and the fish reach sexual maturity within several months. Adults are comparatively long-lived relative to annual killifishes, with lifespans of two or more years recorded in captive conditions.
In the aquarium
Scriptaphyosemion bertholdi is kept almost exclusively by killifish specialists; it does not appear regularly in the general ornamental trade but circulates within killifish societies and dedicated hobbyist networks. A small, densely planted aquarium of 10–15 US gal is adequate for a pair or a trio; heavy planting with fine-leaved species provides the cover and egg-deposition sites the fish use naturally, and floating plants or surface cover reduce light levels toward the diffuse, shaded conditions of forest-stream habitat.
Water should be soft and slightly acidic — pH in the range of 6.0–6.8, hardness minimal, temperature 72–77 °F — maintained with regular small water changes. Filtration should produce only gentle flow; the species is not adapted to strong currents. The aquarium must be tightly covered: like most killifishes, S. bertholdi is an accomplished jumper. Males may be aggressive toward one another and should not be kept together in small aquaria; a single male with multiple females reduces male-male tension and improves breeding productivity. The species is best kept in a species aquarium or with small, non-aggressive fish that share its water-chemistry requirements.
Conservation
The IUCN Red List assessed Scriptaphyosemion bertholdi as Vulnerable (VU) in 2019 (assessor: Dankwa, H., 2020). The assessment reflects the species' restricted range in the lowland forests of Sierra Leone and Liberia and the severe, ongoing degradation of forest-stream habitat across that zone. The Upper Guinean rainforest — the biodiversity hotspot that encompasses the species' entire known range — has been heavily reduced by agricultural expansion, logging, and mining, and continues to decline in extent and quality.
Forest-stream killies are among the most habitat-specific of freshwater fishes: they require clear, chemically stable, shaded water with intact riparian vegetation, and they do not persist in degraded, turbid, or heavily disturbed channels. Water pollution from agricultural runoff, artisanal mining (particularly gold and diamond operations common in Sierra Leone and Liberia), and domestic waste affects the streams the species inhabits. The Guinean Forests Biodiversity Hotspot ecosystem profile documents widespread wetland degradation in the region and identifies endemic aquatic species as disproportionately at risk. For a non-annual species with no diapausing egg bank to bridge population crashes, the loss or permanent alteration of occupied streams carries a high extinction risk at the local and potentially global level. In the aquarium, the species benefits from hobbyist captive-propagation programmes coordinated through killifish associations, which serve as an informal insurance population in the event of further range contraction in the wild.