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The Phenacogrammus interruptus, also called the Congo Tetra, is an African characid known for its metallic reflections and elegant fins. Native to the Congo River basin, it lives in groups and shows its best qualities in a spacious, well-planted aquarium with suitable tank mates. Adult males usually develop longer fins and more striking coloration. This species is collected from the wild and has variable availability in the aquarium trade, giving it an intermediate rarity level. Its peaceful nature, active swimming style and preference for soft freshwater make it an excellent choice for a large community aquarium.

General description of the species

Phenacogrammus interruptus is a schooling fish from the family Alestidae, adapted to open-water life in Central African rivers. It should be kept in a group, preferably with several individuals, because too few companions can make it nervous and limit the expression of its colors. In a mature aquarium, it mainly uses the middle and upper levels, swimming continuously without being excessively boisterous. Males may briefly chase one another and display their fins, especially once the group is established. Despite being a fairly large tetra, it is generally peaceful with similarly sized fish. An aquarium measuring at least 120 cm in length is preferable to provide enough swimming room. Because this species is collected from the wild, careful acclimation and quarantine are sensible practices.

Geographical origin and biotope

Countries of reference: Democratic Republic of the Congo and Republic of the Congo, within the Congo River basin. Phenacogrammus interruptus inhabits tropical forest waterways, tributaries and calm or moderately flowing sections. The biotope often contains soft, slightly acidic to neutral water, darkened by forest cover and organic matter. Banks may be bordered by dense vegetation, while branches, roots and accumulated leaves provide shelter. In the aquarium, moderate lighting, sturdy plants and driftwood recreate this setting better than a completely open layout. Filtration should be effective, but the current should not turn the entire aquarium into a torrent. Stable parameters are more important than chasing extreme values, especially for this wild-collected species.

Precise location and local name

The distribution of Phenacogrammus interruptus lies within the Congo basin in Central Africa, associated with the Congo River and its forest tributaries. The species is linked to the Congo region, although aquarium specimens may come from different collection areas. The international common name Congo tetra is widely used in the English-speaking aquarium trade; Congo Tetra and Congo tetra are also the usual commercial names in English. No separate local vernacular name is retained here as a replacement for these trade names. To support natural behavior, it is better to purchase this fish as a group rather than singly. Availability is variable, so it is considered moderately uncommon in specialized aquarium stores, without being an exceptional rarity.

Appearance and physical characteristics

The body of Phenacogrammus interruptus is elongated and laterally compressed, with a silver to blue-green base color and iridescent reflections that change with the lighting. Adult males usually have more developed dorsal, anal and caudal fins; the caudal fin may show pronounced extensions and violet or blue tones. Females are often stockier, with shorter fins and a less dramatic outline. Coloration depends on age, sex, health and lighting quality. The species reaches about 8 cm in total length, with males generally appearing more impressive. Clean water, varied foods and low stress are essential to bring out its metallic reflections and long fins.

General diet

An omnivore with an insect-oriented diet, Phenacogrammus interruptus readily accepts quality commercial foods once properly acclimated. A base of flakes or small granules formulated for tetras can be supplemented with small frozen or live foods, including brine shrimp, daphnia and mosquito larvae from a safe source. In nature, it likely consumes small invertebrates along with plant or organic material available at the surface and in the water column. Meals should be small and eaten quickly to prevent waste buildup. Offering varied foods twice daily supports body condition and coloration. Protein-rich foods are especially useful for growth, but overfeeding can quickly affect water quality. The priority is a varied diet that suits its small mouth, with a regular portion of frozen or live food to encourage natural behavior.

Essential data

• Name of the original river: Congo River
• Local name used: Congo tetra in the aquarium trade
• Origin of the scientific name: Phenacogrammus identifies the genus; interruptus refers to an interrupted coloration or pattern
• Etymology of the full name: Phenacogrammus comes from Greek and evokes a notable mark or line; interruptus means interrupted in Latin
• Common/vernacular names: Congo Tetra, Congo tetra
• Family: Alestidae
• Subfamily: Alestinae
• Name pronunciation: fee-nah-ko-GRAM-mus - in-ter-RUP-tus
• Discovery: George Albert Boulenger, 1899
• Maximum adult size: About 8 cm
• Water temperature and pH: 23 to 27 °C; pH 6.0 to 7.5
• Appearance of the waterway and surrounding vegetation: Forest waterway, soft water, shaded areas, roots, branches and dense bank vegetation
• Typical tank mates: Phenacogrammus aurantiacus, Alestopetersius brichardi, Congochromis sabinae, Nanochromis parilus, Synodontis nigriventris, Chrysichthys nigrodigitatus
• Temperament and behavior: Peaceful, schooling and active in open water; group keeping recommended
• Water depth: Shallow to intermediate sections of rivers and tributaries
• Sexual dimorphism: Male usually more colorful, more slender and longer-finned; female often rounder
• Bottom structure and flow: Sand, silt, leaves and plant debris; low to moderate flow depending on the sector

In your aquarium

To succeed with Phenacogrammus interruptus, provide a long, covered and fully cycled aquarium with soft to moderately mineralized water, moderate flow and open swimming areas. A sufficiently large group reduces nervousness and allows males to display their fins without concentrating chasing on one individual. Plants, roots and subdued lighting create a reassuring layout. Since this is a wild-collected fish, gradual acclimation, quarantine and a varied diet are especially worthwhile. Regular maintenance, stable temperature and peaceful companions will help preserve its iridescent coloration and natural behavior.