Irrubesco (Kapuas Form)

The Kapuas River form of Carinotetraodon irrubesco originates from the Kapuas drainage of West Kalimantan, the longest river in Indonesian Borneo. Males from Kapuas collections display notably intensified brick-red to deep rust flank colouration compared to Sumatran imports, likely reflecting the highly tannin-stained, very soft, and acidic nature of the Kapuas river system. Females remain brownish with subtle spotting as with all C. irrubesco. The aquarium should closely replicate Kapuas blackwater conditions with very soft, acidic water, tannin staining, and dense planting. The Kapuas form is a specialist acquisition and commands premium collector interest due to its outstanding male colouration.

Water: pH 5.0–6.5, temperature 24–28°C, very soft and acidic; peat filtration or Indian almond leaves recommended. Tank: 40 L per specimen; dense planting, driftwood, dried leaf litter; very dim lighting preferred. Feeding: Small snails critical; frozen bloodworm, daphnia, small brine shrimp; varied diet essential. Breeding: Egg scatterer in blackwater conditions; male guards eggs; soft acidic triggers breeding. Compatibility: Males extremely territorial with one another; one male to two females maximum; avoid nippy species.