Taxonomy & naming
Lacustricola petnehazyi was formally described by Nagy and Vreven in 2018 under the combination Micropanchax petnehazyi, based on specimens from the Tshipokokolo system of the Upper Lufira drainage in the Democratic Republic of Congo. Subsequent revision of the African lampeye genera transferred the species to Lacustricola, the combination now accepted by Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & Fong), which records the valid name as Lacustricola petnehazyi (Nagy & Vreven, 2018). The parenthesised authority signals that the specific epithet has moved from the original combination.
Lacustricola belongs to the family Procatopodidae — the African lampeyes — a group of small, schooling killifishes distributed across sub-Saharan freshwaters. They are distinguished from other killies by the iridescent reflective patch above and behind the eye (the light organ from which the common name derives), small adult size, and a tendency toward open-water schooling behaviour in permanent or semi-permanent shallow habitats. The genus Lacustricola was revised in the 2000s and 2010s to include several species previously split among Aplocheilichthys, Micropanchax, and related genera; L. petnehazyi was one of the more recently added members.
Morphology
Lacustricola petnehazyi is a very small fish: FishBase records a maximum standard length of 0.5 in, consistent with the measurement of approximately 1 in SL reported in the scientific literature describing specimens from the Kay system of the Upper Lualaba drainage. Like other lampeyes, it is slender and laterally compressed, with the characteristic iridescent blue-green reflective patch above and just behind the eye — the 'lampeye' light organ that identifies the group at a glance.
Beyond the distinctive eye patch, the body is translucent to pale brownish, typical of small Procatopodids that live in sun-dappled shallow pools. Sexual dimorphism in the lampeyes is generally subtle: males may show slightly brighter or more extensive iridescence in the eye region and around the body flanks, while females become visibly round-bellied when carrying eggs. Detailed descriptions of fin shape and colour pattern specific to this species remain limited in the published literature given how recently it was described.
Habitat
The species is endemic to the Tshipokokolo system within the Upper Lufira drainage, a tributary network of the Upper Congo River basin in the Democratic Republic of Congo. It occupies ephemeral to seasonal pools — shallow bodies of transparent, slightly brownish water that form at the onset of the rainy season in seasonal wetland habitats. FishBase notes water chemistry of 77–82 °F and pH 6.3–7.2; field data from the Kay system of the Upper Lualaba drainage record a temperature of 81 °F, pH 7.2, and a total dissolved solids level of approximately 120 ppm — moderately mineralised, near-neutral water rather than the acidic blackwater of some West African lampeyes.
These pools are shallow and sunlit, typically vegetated with marginal grasses, aquatic macrophytes, and fine-leaved plants that provide attachment points for eggs and shelter for fry. The seasonal nature of the habitat means water levels fluctuate markedly between the dry and wet seasons, a feature Lacustricola manages as a non-annual species — it does not depend on diapausing eggs to survive dry-season pool loss, but rather persists in the deeper remnant water bodies or moves to connected permanent water when ephemeral pools contract.
Feeding
Like most Procatopodids, Lacustricola petnehazyi is an opportunistic micro-predator. In the wild it feeds primarily on small aquatic invertebrates — midge larvae, water fleas, copepods, and other zooplankton that are abundant in warm, shallow seasonal pools. As a schooling species that inhabits open, well-lit water, it likely feeds continuously throughout daylight hours, picking prey items from the water column and from the surface film.
In captivity, African lampeyes accept a broad range of small live and frozen foods: newly hatched brine shrimp nauplii, daphnia, cyclops, and small bloodworm. Dry foods of an appropriate size — micro-pellets and finely ground flake — are also accepted once the fish have settled, though live and frozen foods are preferred for conditioning adults ahead of spawning. The small mouth size (as expected for a fish under 1 in) limits prey to items no larger than small nauplii or fine powdered food.
Mating
Lacustricola petnehazyi reproduces as a non-annual, continuous egg-layer — a spawning mode shared by most members of the Lacustricola and broader lampeye radiation. Rather than synchronising reproduction to the rainy season and producing diapausing eggs that survive pool desiccation, non-annual lampeyes spawn repeatedly through the warmer months in permanent or semi-permanent water, attaching small batches of adhesive eggs to fine-leaved aquatic vegetation, submerged roots, or similar fine substrate.
Mating is brief and involves a close side-by-side pairing in which eggs and sperm are released in a short spawning act. Only a few eggs are deposited at a time — a single female may lay just a handful per session but will spawn repeatedly over days and weeks. The schooling habit of lampeyes in the wild means males are always in proximity to ripe females, and no elaborate courtship display or territory-holding has been observed in related species.
Breeding
In aquarium conditions, breeding Lacustricola petnehazyi follows the general pattern of non-annual African lampeyes. A well-conditioned group of adults in a densely planted tank will begin spawning readily, depositing adhesive eggs singly or in small clusters among fine-leaved plants such as java moss, hornwort, or spawning mops. Eggs are small and adhesive, adhering to plant surfaces and requiring no intervention from the parents, who do not guard or attend them.
Incubation at temperatures of 77–81 °F takes approximately 10–14 days, consistent with related species. Fry hatch at a very small size and require appropriately fine first foods — infusoria, vinegar eels, or commercial fry powder — before graduating to newly hatched brine shrimp nauplii as they grow. Because adults may consume both eggs and fry, moving spawning mops or plant clumps to a separate rearing vessel at weekly intervals is the practical approach. Growth is relatively rapid under good conditions and juveniles reach maturity within two to three months.
In the aquarium
Lacustricola petnehazyi is effectively absent from the mainstream hobby and is held only by specialist African killifish enthusiasts, if at all. Given its tiny adult size — under 1 in — it is a fish for a small, dedicated species tank rather than a community setup. A 10 US gal aquarium, densely planted with fine-leaved vegetation, provides appropriate housing for a group of six to ten individuals. Tankmates, if any, should be restricted to similarly tiny and peaceful species that will not compete aggressively for food or harass the delicate lampeyes.
Water chemistry should match the documented field parameters: temperature 77–82 °F, pH 6.5–7.5, moderate hardness (100–150 ppm TDS). Gentle filtration — a sponge filter is ideal — avoids the strong currents that would stress a small open-water schooler. The schooling behaviour of lampeyes is best expressed in groups of at least six; a single pair will be shy and difficult to observe.
The iridescent eye patch of the lampeyes is their primary ornamental feature, catching the light as the school turns in unison — best appreciated under a slightly angled light source. Because the species is so rarely collected or bred in captivity, maintaining a healthy captive population through regular spawning is a meaningful contribution to knowledge of the species.
Conservation
The IUCN Red List assessed Lacustricola petnehazyi as Endangered (EN) in 2023. The designation reflects a combination of factors typical of single-basin endemic African killifishes: an extremely restricted native range confined to the Tshipokokolo system of the Upper Lufira drainage, a small estimated population, and ongoing habitat degradation driven by the expansion of artisanal and industrial mining in the Katanga region of the Democratic Republic of Congo.
The Upper Lufira basin sits within one of the world's most intensively mined zones — cobalt, copper, and coltan extraction has expanded significantly since the 2000s, bringing with it associated water pollution (acid mine drainage, heavy metal contamination), sedimentation from erosion, and direct habitat destruction. Agricultural expansion at the margins of the drainage adds further pressure through deforestation, burning, and modification of the seasonal wetland pools that the species inhabits. Introduced fish — particularly Nile tilapia and other widespread species moved around the region for aquaculture — may also pose a predation or competition threat in pools connected to larger water bodies.
Given that the species was described only in 2018, systematic survey data on population size, range extent, and trends remain sparse. Targeted ichthyological surveys in the Tshipokokolo system and the broader Upper Lufira catchment, combined with formal protection of the wetland habitats it occupies, are the most urgent conservation needs.