Mazaruni Rivulus

Rivulus mazaruni is a non-annual killifish from the Mazaruni River basin of Guyana, one of several attractively coloured Rivulus species from the Guiana Shield region. Males display vivid orange-red spotting on a brownish-olive body, and the fins carry additional colour that intensifies with sexual maturity. Females bear the typical Rivulus ocellus at the tail base. The species inhabits soft, acidic forest streams and swampy areas.

Soft, slightly acidic water is important for R. mazaruni, reflecting the blackwater character of its native streams. A 40 L species tank with plant cover and a spawning mop is suitable. Eggs hatch after 10–14 days of incubation in damp peat. The species is peaceful and can be maintained with other small, calm killifish or nano species in an appropriate soft-water community.

R. mazaruni is an attractive and underappreciated killifish from the biodiverse Guiana Shield. Its vivid spotting, interesting origin, and moderate care requirements make it a rewarding species for keepers expanding their knowledge of South American killifish diversity.