Trigonopoma gracile

Trigonopoma gracile, the Slender Rasbora or Lined Rasbora, is a slender, graceful cyprinid endemic to the peat swamps, blackwater streams, and slow rivers of Sumatra, Borneo, and the Malay Peninsula. The body is largely transparent to pale gold with a single fine dark horizontal stripe running from snout to tail. Its delicate build and preference for very soft, acidic, tannin-rich blackwater conditions place it firmly in the specialist category. In the aquarium a blackwater setup with leaf litter, driftwood, and a dark substrate is essential for colour development and long-term health. Very gentle filtration must be used — a sponge filter is ideal. It is extremely peaceful and suits mixed-species nano blackwater tanks with Boraras, Paedocypris, and other Sundaland specialists. Micro-foods are preferred.

Water: Temperature 22–28 °C, pH 4.0–6.5, GH 0–5; very soft, acidic blackwater; tannins essential. Tank: 30 L minimum; blackwater nano tank; leaf litter, driftwood; sponge filter; dark substrate. Feeding: Micro-pellet, baby brine shrimp, cyclops, and micro-worm; small foods only. Breeding: Egg-scatterer; very soft, acidic water required; spawns among fine plants. Compatibility: Peaceful blackwater nano species; ideal with Boraras and Paedocypris.