Tetras · Alestidae

Micralestes stormsi

Boulenger, 1902

IUCNLEAST CONCERN · 2019
CARESNOT LISTED
Scientific size4 in10 cm standard length
Temperature72–79 °F22–26 °C
pH6–7.6alkaline
Hardness (GH)very hard321–446 ppm
Depthnot recorded
DietInvertivore/omnivore; small aquatic invertebrates and microcrustaceans; trophic level 3.2 (FishBase)
BreedingEgg-scattering open spawner (presumed by family analogy); adhesive eggs among vegetation; no parental care
Sexual dimorphismMinimalSexual dimorphism not described in available sources
PhotographsSee photosGoogle Images →

Micralestes stormsi is a small, pelagic characin from the Congo River basin and the waters draining into Lake Tanganyika — including the Rusizi River in Burundi and the Malagarasi River in Tanzania. Described by George Albert Boulenger in 1902 from the Lindi River, it is one of several Micralestes species that sweep through the midwater of Central and East Africa's large river systems in tight, silver-flecked schools. Assessed as Least Concern on the IUCN Red List, it occupies a broad swath of freshwater habitat across three countries and remains largely unstudied in the aquarium hobby.

What's in the name

Micralestes stormsimy-KRAL-es-teez STOR-mzy

Micralestes
  • mikrosGreeksmall
  • alestesGreekquick-moving or nimble; the alestid genus name alluding to the darting schooling behaviour of small characins
stormsi
  • Stormseponyma patronym honouring the Storms family, connected to paleoichthyological work in Central Africa at the time of the original description

Taxonomy & naming

Micralestes stormsi was formally described by the Belgian-born British ichthyologist George Albert Boulenger in 1902, based on specimens collected from the Lindi River in what is today the Democratic Republic of Congo. The type locality anchors the species firmly within the Congo drainage. Eschmeyer's Catalog of Fishes records the valid combination as Micralestes stormsi Boulenger, 1902.

The genus Micralestes belongs to the family Alestidae — the African tetras — a predominantly Afrotropical group that convergently mirrors the South American characid radiation. Alestids are distinguished by features of the jaw dentition and cranial anatomy. Within the genus, Micralestes species are small-bodied, silvery schooling fishes spread across West, Central, and East African drainages. The specific epithet stormsi is a patronym; the cache notes it honours the Storms family, who were involved in paleoichthyological work in the region, though the precise individual commemorated is not confirmed in available sources.

Morphology

Micralestes stormsi is a slender, laterally compressed alestid reaching a maximum standard length of 4 in, as recorded in FishBase. Like other members of the genus it is a pelagic-adapted schooling fish with a fusiform body, moderately forked caudal fin, and the adipose fin that characterises the broader characiform lineage.

The colouration follows the classic small-alestid pattern: a silver ground colour with a bluish or greenish dorsal sheen and a faint lateral stripe that sharpens under certain lighting. Fins are largely hyaline. No detailed meristic or pigmentation data have been published for this species in the sources consulted, and morphological data remain sparse compared with more intensively studied alestids of the genus.

Habitat

The species is widely distributed across the Congo River basin and extends into the Lake Tanganyika peripheral drainages, including the Rusizi River system (Burundi) and the Malagarasi River (Tanzania). FishBase characterises it as a pelagic freshwater fish, typically encountered in the open water of rivers and lakes rather than along heavily vegetated margins or in benthic microhabitats.

Reported water parameters from FishBase place the species in moderately warm, circumneutral to slightly alkaline water: temperatures of 72–79 °F, pH 6.0–7.6, and hardness of 18–25 dH. These figures encompass the range of conditions found across the Congo's main channel and the rift-peripheral rivers, where water chemistry shifts notably between the soft, acidic blackwaters of some Congo tributaries and the harder, more alkaline inflows to Tanganyika.

Feeding

FishBase assigns Micralestes stormsi a trophic level of 3.2, placing it as a secondary consumer. This is consistent with a diet of small aquatic invertebrates — insect larvae, microcrustaceans, and similar zooplankton — supplemented opportunistically by surface-drifting insects. The pelagic habit suggests it forages in the open water column rather than among benthic detritus.

No detailed field dietary studies appear in the available literature for this species. By analogy with other Micralestes and alestid tetras of similar size and trophic level, the diet is presumed to be primarily invertivorous with an omnivorous element in seasons of high terrestrial insect availability.

Mating

No mating or reproductive behavioural data specific to Micralestes stormsi have been published in the sources consulted. By family analogy, alestid tetras in this size range and ecological guild are generally egg-scattering open-water spawners, releasing adhesive or semi-adhesive eggs among fine-leaved aquatic vegetation or in current, with no parental care.

Males in breeding condition in alestid species frequently develop intensified colour or slightly modified finnage, but no such data have been documented for this species. Seasonality of spawning is also undescribed in the available record.

Breeding

Captive breeding of Micralestes stormsi is not documented in the hobby literature consulted. FishBase records no specific breeding data for the species. In the wild, reproductive mode is presumed to follow the alestid pattern of egg-scattering with adhesive eggs deposited among fine-leaved vegetation and no parental care from either parent.

Data on clutch size, incubation period, fry rearing, and larval development are absent from available sources. The species is essentially unknown in the ornamental trade and has not been the subject of captive breeding programmes.

In the aquarium

Micralestes stormsi is rarely if ever encountered in the ornamental fish trade and is effectively unknown as an aquarium fish. No species-specific husbandry guidance appears in the hobby literature consulted. Given its ecology — a pelagic schooling alestid from large river and lake systems — it would require a spacious, well-filtered aquarium with open swimming space, a pH in the neutral to slightly alkaline range, moderate hardness, and temperatures between 22 and 79 °F.

Any prospective keeper would be working with limited precedent and should treat general alestid husbandry guidelines as the nearest available proxy. Hobbyist experience with the genus Micralestes at large is itself sparse, and data on diet, compatibility, and behaviour in captivity for this species should be considered absent rather than assumed.

Conservation

Micralestes stormsi is assessed as Least Concern (LC) on the IUCN Red List, most recently evaluated in 2019. The assessment reflects a stable population across a broad distribution spanning the Congo River basin, the Rusizi drainage in Burundi, and the Malagarasi system in Tanzania — a range extensive enough that no range-wide population decline approaching threshold levels has been identified.

No specific threats are noted in the assessment for this species. The Congo basin as a whole faces pressures from deforestation, artisanal mining, and water-quality degradation in some areas, but none of these appear to have produced detectable range-wide declines for this species to date. Its status warrants periodic review given ongoing habitat change in Central Africa.

Sources

  1. FishBase — Micralestes stormsi Boulenger, 1902
  2. IUCN Red List — Micralestes stormsi: Least Concern (assessed 2019)
  3. Boulenger, G.A. (1902) — Contributions to the ichthyology of the Congo; type locality Lindi River, DRC
  4. FishBase — distribution and habitat notes for Micralestes stormsi

Last reviewed 2026-06-21.

How to cite

Aquarist Atlas (2026). Micralestes stormsi. Aquarist Atlas.https://www.aquaristatlas.com/tetras/micralestes-stormsi/

Where it has been recorded

78 georeferenced records (GBIF). Each point is a field observation or museum specimen — pan and zoom to explore where this species turns up. The coordinates come straight from GBIF and are often rounded or tied to the nearest town or river landing, so a dot can sit just beside the actual water rather than in it.

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