THE NOTHOBRANCHIUS SITE

BE_RMCA_VERT.2025.008.P.0003, male, 41.8 mm SL; DR Congo: Kafila system: Lufira drainage: shallow remnant pools in seasonal floodplain, 8 km northwest of Lutandula village, 10°49'44" S, 27°48'09" E, 1062 m alt.; B. Nagy, A. Chocha Manda & A. Kalumba, 19 Apr 2023 (field code: CD 23-21).

BE_RMCA_VERT.2025.008.P.0004 (1); BE_RMCA_VERT.2025.008.P.0005–0010 (6).

Nothobranchius iridescens is distinguished from all other species of the genus by the unique combination in male colouration of having anal fin with irregular red-brown spots and stripes, creating two irregular submedial and medial bands and with broad yellow subdistal band; and caudal fin with a slender light blue subdistal band, densely marked with irregular red spots, and narrow dark brown distinct distal margin.

Subgenus: Zononothobranchius

Species group: N. brieni group

Nothobranchius iridescens was established as a species by Nagy in 2025.

DR Congo: Kafila system: Lufira drainage: shallow remnant pools in seasonal floodplain, 8 km northwest of Lutandula village, 10°49'44" S, 27°48'09" E, 1062 m alt.

This species is endemic to seasonal freshwater habitats of the upper Congo drainage in south-eastern DR Congo. It is currently known from ephemeral pools and marshes on floodplains associated with the Kafila river in the Lufira system. The Kafila is a major right bank affluent entering the middle Lufira just below the Mwadingusha Falls, which isolates the middle from the upper Lufira.

Upper Lualaba (545)

1062 m

The type locality on 19 April 2023 was an ephemeral pool formed in the floodplain of the Kafila River. The pool was about 50 cm deep at its deepest point, the water was turbid, and it covered an area that was partly overgrown with grass.

None

The species has an annual life cycle.

Embryonic development under captive conditions in peat moss is about three to four months at room temperature.

Maximum size reported: 43.0 mm SL (BE_RMCA_VERT.2025.008.P.0004, paratype, male)

Not known

The specific epithet iridescens is a Latin participial adjective deriving from the ancient Greek word iris (ἶρις), rainbow, referring to the colourful appearance of the males, containing different colours of the rainbow, such as yellow and red in the fins, reflective blue on the body slightly shifting hue depending on the angle of light.

Not evaluated

Recommended as Endangered in Nagy, 2025.

​     Nagy, B. 2024. Off the (badly) beaten tracks. Practical Fishkeeping, 2024: 68–76. [collecting as Nothobranchius sp. Lutandula]

    Nagy, B. 2025. Review of cyprinodontiform fishes in the upper Congo drainage with descriptions of four new species of seasonal Nothobranchius (Nothobranchiidae) and a new species of ‘Lacustricola’ Lampeye (Procatopodidae) in South-Eastern DR Congo. Ecology and Diversity, 2 (2), 10006. [taxonomy as Nothobranchius iridescens, distribution, ecology]