Taxonomy & naming
Scriptaphyosemion chaytori was originally described by Erwin Roloff in 1971 as Roloffia chaytori, published in the German aquarium journal Die Aquarien und Terrarien Zeitschrift (DATZ), volume 26, issue 6. The type locality is a stream draining from the Rokupr pumping station in western Sierra Leone. The species has accumulated several synonyms in the killifish literature — Aphyosemion roloffi and Aphyosemion chaytori have both been applied at various points — before being placed in the genus Scriptaphyosemion, which the Catalog of Fishes (Eschmeyer, Fricke & van der Laan) recognises as the valid combination for this group of West African non-annual killies.
Scriptaphyosemion is a genus of the family Nothobranchiidae, the African killifishes, and sits among the non-annual lampeye-allied lineages of the region rather than with the peat-burying annual genera. The karyotype is recorded as n=21. The species' placement and synonymy reflect the broader flux that characterised West African killifish taxonomy through the 1970s–2000s, during which genera such as Roloffia were periodically lumped with Aphyosemion and then re-separated.
Morphology
Adults reach a maximum of approximately 2 in, with FishBase recording 2 in standard length. The body form is slender and laterally compressed in the manner of most Nothobranchiid killies, with the dorsal fin set well back toward the caudal peduncle.
Sexual dimorphism is pronounced and consistent. Males are pale blue-grey on the body with red markings concentrated on the dorsal, anal, and caudal fins; the outer margins of the unpaired fins carry a pale blue border. The Kasewe Forest and Kasewe Hills population is documented as producing males with particularly intense blue colouration. Females are less vivid in overall hue but are distinguished by a pattern of spotting along the flanks that is reportedly distinctive for this species within its range. The combination of blue-bodied males with red-margined fins places the species in the broader aesthetic tradition of West African forest killifishes, though it lacks the elaborate fin extensions of some congeners.
Habitat
Scriptaphyosemion chaytori is known from multiple drainage systems in western Sierra Leone: the Sewa, Little Scaries, Great Scaries, and Taia rivers, with documented populations at Rokupr, Kasewe Forest, Kasewe Hills, Ngabu, Fulawahun, Kamabai, Pujehun, Njala, Porto Loko, and Bo. The type locality is associated with a pumping station stream near Rokupr in the coastal plain.
The species inhabits small brooks and streams shaded by dense jungle-canopy cover. The American Killifish Association reference notes high oxygen levels and deep shade from overhanging trees as characteristic of occupied habitat. Water chemistry from the AKA reference records pH 6.0–7.0 and total hardness 1–7 dGH, with temperature in the range 73–75 °F — soft, slightly acidic to neutral water consistent with the laterite and forest-soil drainage of the Sierra Leone coastal zone. This is permanent or near-permanent stream habitat, not the ephemeral seasonal pools that characterise annual killi territory.
Feeding
No detailed wild dietary study has been published for Scriptaphyosemion chaytori specifically. As a small, insectivorous-type nothobranchiid inhabiting forest streams, it is expected to prey on small invertebrates, aquatic insects, insect larvae, and zooplankton — the diet typical of similarly sized West African non-annual killies in comparable microhabitats.
In aquarium conditions, the species is reported to accept small live and frozen invertebrates readily. Newly hatched brine shrimp (Artemia nauplii) are used successfully for rearing fry, and adults take small frozen bloodworms, daphnia, and similar prey items without difficulty. Feeding several small meals daily rather than a single large portion suits the active metabolism of this small fish and keeps condition good.
Mating
Scriptaphyosemion chaytori is a non-annual killifish and a surface plant-spawner — its reproductive mode is fundamentally different from the peat-burying annual killies with which it shares the broader West African killifish community. Rather than depositing eggs in the substrate to survive drought in diapause, pairs of chaytori spawn over and among floating vegetation, surface plant roots, or synthetic spawning mops positioned near the water surface. Eggs are adhesive and are laid continuously over extended periods rather than in a single mass-spawning event.
The AKA reference documents that Scriptaphyosemion chaytori spawns at the surface, in direct contrast to its congener S. roloffi which spawns on the bed — a difference that has practical implications in the aquarium, since the two species require different spawning setups. Males court females with spread fins and colour display; because the species is not highly aggressive by killifish standards, pairs can often be maintained together in a well-planted setup.
Breeding
Eggs are deposited singly or in small numbers into floating vegetation or mop fibres and measure approximately 0.5 in in diameter. Incubation takes place fully in water, with no desiccation or diapause phase — the key non-annual characteristic. Hatching occurs in 12 days to 3 weeks depending on temperature, giving a relatively fast developmental pace compared with annual killifish eggs that must endure weeks or months of dry storage.
Fry are large enough at hatching to accept newly hatched brine shrimp as a first food, simplifying rearing considerably. The AKA source records that fish reach sexual maturity at 6–7 months, and spawning has been documented in individuals up to 2.5 years old — a lifespan far longer than the one-season annual killies, and consistent with the permanent-water habitat the species occupies in the wild. Because eggs are laid continuously over days and weeks, regular collection of mop or plant material and transfer to a separate hatching container is the standard hobbyist approach to maximising fry production.
In the aquarium
Scriptaphyosemion chaytori has been described as rarely seen in the aquarium hobby; the AKA reference, writing around 2000, classified it as uncommon, and it has remained a specialist-circle fish rather than entering mainstream trade. Those who do maintain it report it to be manageable, provided the soft-acidic water chemistry of its Sierra Leone stream habitat is replicated: pH 6.0–7.0, hardness well below 10 dGH, and temperature 73–77 °F suit it well. Temperatures above 79–81 °F stress West African non-annual killies over time.
A tank for a pair or trio need not be large — a well-planted 10–15 US gal aquarium with a dark substrate, floating plants or a spawning mop, and gentle filtration through a sponge filter suits the species well. Overhead lighting filtered by floating plants mimics the deep jungle shade of the natural streams. Tankmates, if kept at all, should be small, peaceful, and of similar water-chemistry requirements. The surface-spawning habit means floating Indian fern (Ceratopteris thalictroides), java moss attached near the surface, or a standard killifish spawning mop provides ready spawning sites. Regular water changes with soft, slightly acidic water maintain health and encourage continued spawning.
Conservation
The IUCN Red List assessed Scriptaphyosemion chaytori as Vulnerable (VU) in 2019, reflecting genuine concern about population status in its restricted Sierra Leone range. The species is a single-country endemic limited to the coastal drainages of western Sierra Leone — a geography that concentrates all conservation risk in one small area. Sierra Leone has experienced extensive deforestation and land conversion in its coastal and lowland zones, and the small, heavily shaded forest streams that chaytori inhabits are directly threatened by removal of riparian and canopy vegetation. Changes in hydrology that convert permanently flowing streams to seasonal torrents or drying channels are incompatible with a non-annual species.
The multiple documented populations — Rokupr, Kasewe, Ngabu, Fulawahun, Kamabai, Pujehun, Njala, Porto Loko, and Bo — represent some geographic spread across the Sewa and Scaries river systems, which is a partial buffer against total extirpation from a single event. However, the distribution remains confined to one country and the pressures on its forest-stream habitat are ongoing. The species' rarity in the ornamental trade means captive populations offer little conservation redundancy. The Kasewe Forest, which harbours the population noted for intense male colouration, has some protected status as a Forest Reserve, which may provide partial protection for that population.