Rhombo Barb

Systomus rhombeus (formerly Puntius rhombeus) is found in the peat swamp forests of Sumatra, Borneo, and the Malay Peninsula — habitats with extremely acidic, tannin-stained water and low mineral content. The distinctive large rhombus or diamond-shaped blotch on the flank, combined with reddish fin colouration, makes it one of the more visually distinctive small barbs available. It is not a beginner species as it requires specific soft-water conditions to thrive.

Water: 24–28°C, pH 4.5–6.5, very soft water (GH 1–6); peat or blackwater conditions essential. Tank: 60 L minimum; heavily planted with Indian almond leaves, driftwood, and dark substrate. Feeding: Omnivore; small flake, micro-pellets, and frozen micro-invertebrate foods. Behaviour: Peaceful schooler; keep in groups of 6+; becomes more active and colourful in correct conditions. Compatibility: Soft-water specialist companions only: small rasboras, chocolate gouramis, micro tetras.