Taxonomy & naming
Microctenopoma congicum was originally described by George Albert Boulenger in 1887 as Ctenopoma congicum, based on material from the Congo River. The species was subsequently moved to the genus Microctenopoma, which separates the smaller, more slender African bushfishes from the larger species retained in Ctenopoma sensu stricto. Synonyms include Anabas congica and Anabas congicus, reflecting an older and broader view of anabantoid classification. Eschmeyer's Catalog of Fishes records the current valid name as Microctenopoma congicum (Boulenger, 1887), with the parenthetical authority indicating the genus-level transfer. The karyotype has been documented at 2n = 46 (karyotype formula 7 ft+44A, fundamental arm number 48), consistent with the family Anabantidae.
The genus name Microctenopoma derives from the Greek mikros (small) and the genus Ctenopoma, itself from ktenos (comb) and poma (cover or operculum), referring to the serrated edges of the preopercle and opercle that characterise this group of anabantoids. Within Microctenopoma, M. congicum is placed firmly in the African clade of the broader anabantoid radiation and shares the group's hallmark labyrinth organ.
Morphology
Microctenopoma congicum is a slender, moderately compressed anabantoid. Males reach approximately 2.5 in standard length; females are somewhat smaller, typically around 2 in SL. The body is elongated relative to many gouramis, with a pointed snout and a large mouth suited to seizing small prey. The opercle and preopercle carry the serrated edges — the cteno- element of the genus name — that distinguish Microctenopoma from smooth-cheeked anabantoids.
Colouration in this species is subdued compared to some relatives: a brownish to olive-grey base with faint vertical barring on the flanks that may intensify or fade depending on mood and condition. The tail fin often shows faint spotting or patterning. Males in breeding condition may develop a darker, more contrasting coloration on the head and anterior body. Unlike the brilliantly coloured ornate ctenopoma (M. ansorgii), M. congicum is more cryptic, relying on camouflage among leaf litter and vegetation rather than conspicuous display.
Habitat
Microctenopoma congicum is a freshwater species distributed across the lower and central Congo River basin, with confirmed records from the Democratic Republic of Congo, Republic of Congo, Central African Republic, and the Cabinda enclave of Angola and Gabon. It is a benthopelagic species of still and sluggish waters — swamps, backwaters, flooded forest margins, and densely vegetated pools — where low flow and abundant cover suit its ambush hunting style.
As a labyrinth fish, M. congicum breathes atmospheric oxygen using the suprabranchial labyrinth organ, an adaptation that allows it to thrive in warm, poorly oxygenated water where gill-breathing fish struggle. FishBase records water temperatures of 73–81 °F and a pH range of 6.8–7.8, with hardness up to 25 dH, suggesting a tolerant generalist that spans a wide range of natural water chemistries across its large drainage range. Dense aquatic and marginal vegetation is the consistent feature of occupied microhabitats.
Feeding
Microctenopoma congicum is a carnivore and an ambush predator. In the wild it takes small invertebrates — aquatic insect larvae, small crustaceans, worms — and will consume fry and small fish of appropriate size. The large mouth relative to body size reflects this predatory habit: the fish drifts motionlessly among stems or rests on the bottom before striking.
In the aquarium, most specimens adapt to accept frozen and live foods readily: bloodworm, tubifex, Daphnia, brine shrimp, and small earthworm pieces are all taken. Dry foods are accepted by some individuals, particularly pellets that sink slowly. A varied diet of small live and frozen items best replicates the natural feeding pattern and keeps fish in good condition. Overly large tankmates or slow-moving fry are at risk, and conversely, very small Microctenopoma may be bullied if housed with larger, more aggressive fish.
Mating
Microctenopoma congicum is a bubble-nest builder. The male constructs a loose raft of mucus-bound bubbles at the water surface, typically anchored beneath floating vegetation or under a broad leaf. Courtship follows the classic anabantoid pattern: the male displays to the female with erect fins and intensified colouration, herding her toward the nest site. When she is receptive, spawning occurs in the anabantoid embrace, with the male wrapping around the female as she releases eggs.
Spawning behaviour in the related M. ansorgii — the most closely studied congener — involves the male building a small, loose bubble nest among floating plants, with the pair spawning in repeated embraces producing batches of buoyant eggs. This pattern is expected to hold broadly for M. congicum. The male is territorial around the nest during and after spawning and will defend it aggressively against other fish, including the female.
Breeding
Breeding Microctenopoma congicum follows the anabantoid bubble-nest protocol. A separate, well-planted breeding tank with gentle or no filtration — a sponge filter on its lowest setting — and floating plants such as water sprite or hornwort provides the conditions for nest building and fry survival. The male builds the bubble nest at the surface; once eggs are deposited during the spawning embrace, they float up and are collected into the nest by the male.
Based on the congener M. ansorgii, clutches in small Microctenopoma can number up to several hundred eggs; hatching occurs within roughly 24 hours at breeding temperatures, with fry becoming free-swimming after a further 2–3 days. The female should be removed after spawning to prevent the male from driving her into a corner, and the male removed once the fry are free-swimming, as paternal care wanes and he may then prey on the brood. First foods for the tiny fry should be infusoria or commercial liquid fry food, followed by freshly hatched brine shrimp nauplii as the fry grow.
In the aquarium
Microctenopoma congicum is a quiet, relatively peaceful anabantoid for a species-specific or carefully chosen community aquarium. Its small size — under 3 in — means it can be kept comfortably in a modest aquarium of 23.5 in or more, but the tank must be densely planted, with floating plants to anchor bubble nests and subdued lighting to encourage the fish to venture into open water. Being a labyrinth fish, it must always have access to the air surface; a tight-fitting lid reduces draughts and maintains the warm, humid air layer above the water that prevents chilling the labyrinth organ.
Water conditions should replicate the warm, still waters of its native basin: 73–81 °F, pH 6.8–7.8, and low to moderate hardness. Gentle filtration that avoids strong current is important — this is not a species for a fast-flowing, well-aerated aquarium. Tankmates should be peaceful, of similar or smaller size, and not fast or boisterous enough to outcompete M. congicum at feeding. Dwarf rasboras, small Corydoras, and other small anabantoids of similar temperament can work. The fish is an ambush predator and will take small fry or very small fish, so mixing with nano fish should be done cautiously. Surface access and dense vegetation are the non-negotiable elements of successful long-term care.
Conservation
Microctenopoma congicum is assessed as Least Concern on the IUCN Red List (assessed 14 August 2018). The species has a large range across the Congo basin — one of the most extensive and largely intact tropical freshwater ecosystems on Earth — and no major threats have been identified that would trigger a more elevated category under IUCN criteria. The Congo River drainage supports huge volumes of freshwater habitat, and the species' broad tolerance of water chemistry across the basin supports a stable population.
While the Congo basin faces growing pressure from deforestation, artisanal mining, and agricultural expansion in some areas, the scale of the basin and the lack of targeted commercial collection for M. congicum have left the species in a secure position. Aquarists obtaining specimens should seek tank-bred stock where available, both to support responsible fishkeeping and to reduce any local collection pressure. GBIF records approximately 170 occurrence records for the species, reflecting its moderate documentation across its range.