Taxonomy & naming
Procatopus nototaenia was described by George Albert Boulenger in 1904 from material collected near Kribi, a coastal town in what was then the German Cameroon protectorate, approximately 9–16 mi inland from the Atlantic coast. The description appeared in the Annals and Magazine of Natural History (series 7, volume 14, page 20, 1904). Boulenger erected the genus Procatopus at the same time, and P. nototaenia remains its type species.
The genus Procatopus belongs to the family Procatopodidae — the African lampeyes — a group of non-annual killifishes distributed across West and Central Africa. Procatopodidae was formerly treated as a subfamily of Poeciliidae or Aplocheilidae but is now recognised as a distinct family. Within the family, Procatopus is distinguished by its larger size relative to most lampeye genera and by the pronounced dorsal and anal fin development that gives the species part of its common name.
Some killifish specialists and importers, notably Aquarium Glaser, have noted that specimens from different collection localities — including material from Yabassi, in the Wouri River drainage further north — may represent an undescribed species or a distinct population, and the taxonomic boundaries of P. nototaenia sensu stricto remain under informal discussion. Catalog of Fishes (Eschmeyer, CAS) currently treats Procatopus nototaenia Boulenger, 1904 as the valid name for all material assigned to the species.
Morphology
Procatopus nototaenia is the largest member of its genus, with males reaching approximately 2.5 in total length and females remaining smaller, reaching around 1.5 in TL (FishBase). The body is slender and laterally compressed, typical of the lampeye family, with the profile rising toward a moderately high dorsal fin set well back on the body. Both the dorsal and anal fins are notably large and well-developed in males — the character that inspired the common name 'large finned lampeye'.
The species displays the iridescent supraorbital photophore that defines the lampeye group: a patch of light-refracting tissue above and behind the eye that glows with a blue-green or silver sheen in reflected light. This structure is more pronounced in males and is thought to play a role in species recognition and mate attraction in the low-light conditions of forest stream habitats. General body colouration is silvery to pale olive with a subtle metallic sheen on the flanks; males develop more vivid fin colouration during display.
Sexual dimorphism is clear. Males are larger, more brightly coloured, and carry the more developed dorsal and anal fins; females are smaller, plainer in colour, and rounder-bodied when gravid.
Habitat
In the wild, Procatopus nototaenia inhabits small rivers and brooks in the coastal lowland forest zone of Cameroon. FishBase records its preference for the faster-flowing, better-oxygenated sections of these watercourses — streaming runs rather than still backwaters — under closed forest canopy where light penetration is limited and leaf litter and submerged wood accumulate on the streambed. The British Killifish Association notes that the species swims mainly in the upper water column of clear, moving water.
Water in these coastal forest streams is typically cool to warm (70–84 °F across the year), soft and slightly acidic to neutral, and high in dissolved oxygen owing to the current. The type locality near Kribi sits in a zone of humid equatorial rainforest receiving high rainfall year-round, meaning the streams are permanent and do not experience the dry-season desiccation that drives the annual killifish life strategy. Submerged wood and root masses in the current provide shelter and spawning substrate.
The documented collection locality of Yabassi, in the lower Wouri River basin, represents a second population site some distance north of Kribi and at a slightly different drainage. Both sites lie within Cameroon's narrow coastal lowland forest belt, and the species appears to be endemic or near-endemic to this zone.
Feeding
Procatopus nototaenia is an invertivore, feeding in the wild on small aquatic and terrestrial invertebrates — insects, insect larvae, microcrustaceans, and zooplankton — that fall onto or drift through the water surface and the current. The upturned mouth and preference for the upper water column are consistent with a surface and mid-water feeding strategy, and the species likely takes emerging and fallen insects as a significant dietary component in its forest stream habitat.
In captivity, the fish accepts small live and frozen invertebrates readily: daphnia, cyclops, mosquito larvae, and artemia are all suitable. Small dried foods of appropriate particle size are taken by acclimatised specimens, though live and frozen foods maintain better condition and colouration. The relatively small size of the fish, particularly females, means that food particle size matters — oversized food items are refused or ignored.
Mating
Procatopus nototaenia is a non-annual killifish and a continuous, opportunistic spawner typical of permanent-water lampeyes. There is no diapause, no seasonally driven mass-spawning event, and no dormant egg stage in the substrate — the species breeds year-round when conditions are adequate. Courtship is initiated by the male, who displays his enlarged dorsal and anal fins and the iridescent supraorbital organ at close range to the female, using fin posturing and lateral positioning to signal fitness.
The British Killifish Association records that spawning takes place on fine-leaved plants or spawning mops, with the pair depositing a small number of adhesive eggs at a time during each spawning act. This scatter-and-continue pattern — a few eggs placed at each encounter rather than a single large clutch — is characteristic of the lampeye subfamily and is well-matched to the low-predation, forested stream environment where eggs can mature undisturbed over a period of days to weeks. The iridescent photophore above the eye is presumed to function in species recognition under the dim conditions of forest stream habitats, reducing mismating between co-occurring killifish species.
Breeding
Because Procatopus nototaenia is a continuous spawner in permanent water, there is no conditioning period analogous to a dry season required to trigger breeding — a mature, well-fed pair in good water quality will spawn without special induction. The British Killifish Association recommends a spawning temperature of around 75 °F (75 °F) and the provision of fine-leaved plants or synthetic spawning mops as egg-deposition sites.
Eggs are adhesive and relatively few are produced per spawning encounter; over a period of days or weeks a pair will accumulate a modest number of eggs scattered among the plants. The eggs can be left in situ in a species-only tank, removed to a hatching container, or the adults can be moved to a fresh tank after a spawning period. Incubation takes approximately two to three weeks at aquarium temperatures; the fry are small at hatching and require suitably fine first foods — infusoria, newly hatched artemia nauplii, or commercially prepared fry foods — before graduating to larger items. Growth is moderate. The species is noted by FishBase as very difficult to maintain in captivity, and successful breeding demands stable, high-quality water with good oxygenation and flow.
In the aquarium
Procatopus nototaenia is regarded as one of the more challenging lampeye killifishes to keep successfully. FishBase flags it as very difficult to maintain, and the demand for well-oxygenated, clear, moving water is not easily reproduced in a standard still aquarium. A species tank with gentle but consistent water movement — provided by a powerhead, spray bar return, or sponge filter with airflow — is preferable to a static community setup. Water quality must be high and consistent: regular partial water changes, low dissolved organic load, and temperatures in the 70–79 °F range suit the species best.
The fish is a schooling species that swims primarily in the upper half of the water column. A group of six or more individuals will display more natural behaviour and reduced individual stress compared with isolated pairs. A heavily planted tank with floating cover and subdued lighting mimics the shaded forest stream environment and encourages normal activity. Tankmates, if any, should be small, peaceful species with similar water requirements; the large fin development of males makes them potential targets for fin-nippers.
The species is not frequently encountered in the trade and is primarily kept by specialist killifish hobbyists. Material from different collection localities — Kribi and Yabassi have both appeared in the hobby — may represent distinct populations with slightly differing care requirements. Keepers are encouraged to maintain collection-locality records and avoid mixing populations of uncertain provenance.
Conservation
No formal IUCN Red List assessment has been completed for Procatopus nototaenia, and the species carries no official conservation status. Its apparent restriction to the narrow coastal lowland forest belt of Cameroon — a zone facing significant pressure from logging, agricultural expansion, and infrastructure development — is a cause for concern even in the absence of quantitative population data.
The lowland rainforest streams of coastal Cameroon are a biodiversity hotspot harbouring many narrow-range endemic freshwater fishes, and the quality of habitat in small forest brooks is closely tied to canopy integrity. Deforestation raises water temperatures, increases sedimentation, and reduces the invertebrate drift that underpins the food web of these streams. The species' dependence on clear, well-oxygenated, shaded current habitats means it has limited tolerance for the warm, turbid conditions that follow forest clearance.
The killifish hobby has historically provided a secondary conservation buffer for localised African lampeye species through captive maintenance of collection-locality strains, and several killifish societies actively encourage the documentation and careful breeding of such material. Given the taxonomic uncertainty around the Yabassi population, maintaining clean locality records in captive collections has additional scientific value pending a formal revision of the genus.