Taxonomy & naming
Nothobranchius palmqvisti was described by the Swedish zoologist Einar Lönnberg in 1907 from material collected during the Kilimanjaro-Meru expedition of 1905–1906. The type locality is recorded as an inundated cocoa plantation at Tanga, in coastal Tanzania (approximately 05°04′ S, 39°04′ E). Lönnberg's original measurement gives a maximum total length of 1.5 in — the figure used by WildNothos and FishBase as the basis for the species' recognised size limit. Because the species was moved from the original genus to Nothobranchius, the authority appears in parentheses as (Lönnberg, 1907).
Eschmeyer's Catalog of Fishes places N. palmqvisti within the subgenus Adiniops, in the N. guentheri species group — a clade of moderately sized, coastal East African annuals with broadly overlapping distributions. The species has historically been confused with the closely related N. foerschi and with undescribed populations sometimes listed as N. sp. mugeta; the American Killifish Association has documented this confusion in the hobby literature, noting that true N. palmqvisti is distinguishable and reliably bred once the taxonomic identity is confirmed. Syntopic species at collection sites include N. kwalensis (occurring at roughly 26% of shared sites) and N. melanospilus (approximately 7%).
Morphology
Males reach a maximum of approximately 1.5 in TL (Lönnberg 1907; WildNothos), with most aquarium individuals maturing at around 1.5 in. Females are smaller and more plainly coloured, conforming to the strong sexual dimorphism typical of the genus. FishBase also lists a reported maximum of 1.5 in TL, consistent with Lönnberg's original measurement.
Males carry the intensely patterned flanks characteristic of the N. guentheri group: a base of blue, turquoise, or greenish iridescent scales overlaid with red-edged scale markings, with a caudal fin that may display red and black banding. Colouration varies among collection-point strains — hobbyists familiar with multiple populations note appreciable differences in the depth of red and the extent of blue iridescence between, for example, Gezani and Ramisi fish. Females are cryptically marked in olive-brown with scattered dark speckling, rounded fins, and a notably deeper belly profile when gravid. Both sexes show the compressed, moderately elongate body form standard across the genus.
Habitat
The species is endemic to the coastal lowlands of Tanzania and south-eastern Kenya, distributed in the drainages of the lower Pangani River (below Pangani Falls), the Umba River (both the Tanzanian and Kenyan portions of its catchment), and the Ramisi River system of south-eastern Kenya. WildNothos documents 16 collection-point records, at elevations ranging from 56–443 ft above sea level. The range includes populations around Tanga (Tanzania), Mwangwei Village, Machimboni, and Gezani.
Habitat consists of shallow, temporary pools, floodplain swamps, and seasonally inundated ditches — standing water bodies that fill during the long or short rains and dry out completely during the dry season. Measured field water parameters from WildNothos give temperatures of 76–81 °F, pH 6.50–7.31, and TDS of 53–721 ppm, reflecting the considerable variation between sites from very soft, near-neutral pools to harder, mineral-rich water. FishBase records a broadly representative pH of 6.5 and hardness of approximately 4 dH for typical habitat. The surrounding landscape is coastal savanna and low-elevation scrub, with soils that retain sufficient moisture for buried eggs to survive the dry season even as standing water disappears entirely.
Feeding
Like most members of the genus, N. palmqvisti is a generalist predator in the wild, taking whatever invertebrates, small crustaceans, and zooplankton are available in its temporary-pool habitat. The brief productive season — from pool formation through the growth phase to breeding — selects strongly for rapid growth, so the fish feeds aggressively whenever food is present.
In the aquarium, Palmqvist's notho presents no feeding difficulties. It accepts live foods with particular enthusiasm — Daphnia, Artemia nauplii, Cyclops, blackworm, and small chironomid larvae are ideal staples — but adapts readily to high-quality frozen and freeze-dried alternatives. The killi.co.uk species profile notes a preference for live foods; gut-loading live invertebrates before feeding improves condition and colouration in males. Dried pellets are accepted by many individuals, especially fish raised on them from fry. A varied diet accelerates growth and promotes the vivid colouration that makes males so attractive.
Mating
Nothobranchius palmqvisti is an annual species with a substrate-diving spawning strategy characteristic of the genus. In the wild, as pools fill with seasonal rains and water temperatures are seasonally moderate, males establish loose dominance territories and display intensely to females, flaring fins and presenting their full lateral colouration. Competition between males is vigorous; in confined space this competition can result in injury to subordinate fish.
Spawning is initiated when the female accepts a displaying male and the pair dive together into the soft substrate — peat, mud, or fine detritus — where eggs are deposited singly, buried just beneath the surface. The American Killifish Association describes N. palmqvisti as an adaptable and active species whose males readily display and court; sex ratio in captive populations is often skewed toward females, which is consistent with the high-cost male competition seen across the genus. Multiple spawning events occur across the lifespan of the pool, and a single female may contribute eggs across many encounters.
Breeding
The eggs of N. palmqvisti are buried in the substrate and are drought-resistant, entering diapause — a state of arrested development — that allows them to survive the complete desiccation of the home pool for weeks to months. Embryonic development at room temperature in damp peat or coir takes approximately two to three months (killi.co.uk; WildNothos), after which eggs are ready to hatch when re-wetted. In the hobby, the standard protocol is to collect peat from the tank bottom, partially dry it, and store it in sealed plastic bags at room temperature for two to three months before re-wetting to trigger hatching. FishBase records incubation of two to four months.
The life cycle is described by WildNothos as semi-annual, reflecting the fact that in favourable seasons some populations may complete more than one wet-season cycle, though the adult fish still die as the pool dries. Adults in the aquarium are typically short-lived — a year or less under hobby conditions is normal. Breeding is rated easy by the killi.co.uk profile and by the AKA, and N. palmqvisti is considered one of the more approachable entry-level annual Nothobranchius for killifish beginners. Reported strains in the hobby include Gezani TAN 95-16, KF 01-1 Mwangwei Village, Machimboni TAN 98-2, Pangani TZ 94-7, and Ramisi KE 01-12, each with distinct collection histories and, in some cases, subtly different colouration.
In the aquarium
Palmqvist's notho is well-suited to small, covered aquaria of 10–15 US gal or more, maintained with a dark substrate and dim lighting that brings out male colouration. A tight-fitting lid is essential — annual killies are active jumpers. Water conditions are flexible within the broad range encountered in the field: the AKA notes that N. palmqvisti adapts readily from cool (around 68 °F/68 °F) to warmer conditions in the high 20s °C, and the killi.co.uk profile documents hobbyist reports spanning 50–81 °F, with 68–81 °F the most commonly reported optimum. The species tolerates water from near-neutral to mildly alkaline (pH up to approximately 7.3) as well as softer and harder conditions, reflecting the chemical variability of its native pools.
The species is best kept in a small species group — one male with two or three females — to spread aggression and ensure steady egg production. Dense clumps of floating plants or fine-leaved vegetation and a deep layer of fine peat or coco coir substrate serve both as spawning medium and as refuge for females escaping male attention. The AKA describes the fish as a good community species for tanks housing similarly sized killies and small, peaceful companions that can tolerate the same temperature range. Peat collected from the substrate every two to four weeks, then dried and stored, forms the basis of the breeding cycle. The species is described as easy, adaptable, active, and pretty — an ideal introduction to annual Nothobranchius husbandry.
Conservation
The IUCN Red List assessment of 2019 (Nagy & Watters) lists Nothobranchius palmqvisti as Vulnerable under criterion B1ab(iii) — indicating a restricted extent of occurrence combined with an ongoing, inferred decline in the quality of its habitat. The assessment represents an upgrade from the Least Concern rating assigned in 2006, reflecting recognition of the cumulative pressure on the coastal lowland wetlands that the species depends on.
The primary threats are habitat loss and degradation. The temporary pools, floodplain swamps, and seasonally inundated ditches of coastal Tanzania and south-eastern Kenya are fragile ecosystems highly sensitive to drainage for agriculture and infrastructure, diversion of the river systems for irrigation, and deforestation of surrounding catchments that alters seasonal flood regimes. Because the species' range is geographically restricted — essentially the coastal strip of two countries between roughly Tanga and the Ramisi River — any contraction of the total pool area removes populations permanently. Annual killies have no ability to recolonise dried-out habitats from elsewhere; each pool holds its own dormant egg bank, and if a pool is drained or permanently converted before that bank matures, the local population is extinguished.
The species remains reasonably well established in the killifish hobby, where multiple georeferenced strains are maintained by enthusiasts and killifish associations. Hobby collections from named localities — Gezani, Pangani, Ramisi, Machimboni, Mwangwei — constitute an informal ex-situ reserve that preserves genetic diversity from specific collection points. This does not substitute for in-situ protection of the coastal wetland habitats, but it ensures that the species survives in captivity even as wild habitat continues to contract.