Blue-lined Rasbora
Trigonopoma gracile
A delicate blackwater rasbora with variable color forms from Borneo's forest streams.
About
Found threading through forest streams and dark, tannin-rich blackwater habitats across Indonesia and Malaysia, Trigonopoma gracile is a small, slender cyprinid that sits within a genus carved out of the old catch-all Rasbora grouping following phylogenetic work in the 2010s. Its genus name references the distinctively shaped triangular opercle that separates these fish from close relatives. One of the more interesting things about this species is its variability. Fish from different collection localities can look noticeably different, with some showing richer fin coloration or an additional reddish stripe along the flank, which has caused confusion in the hobby and in the literature over the years. At a small adult size, it works well in a peaceful Southeast Asian community alongside similarly sized cyprinids, compact loaches, and certain anabantoids. Keep it with calm, unhurried tankmates. Anything boisterous or fast-moving risks edging it away from food. Given its blackwater origins, soft acidic water will bring out the best in it, though it tolerates a reasonable range. Breeding appears unrecorded in captivity. It's a manageable choice for a beginner willing to replicate soft, slightly acidic conditions, and a rewarding one for anyone building a biotope around Bornean stream species.
Similar species
Other fish you might consider
Good tank mates
Species that tend to coexist peacefully with Blue-lined Rasbora
From the same region
Share the same natural habitat. Great for a biotope-themed tank
Frequently asked questions
- How big does the Blue-lined Rasbora get?
- The Blue-lined Rasbora reaches about 1.5–2" as an adult.
- What size tank does the Blue-lined Rasbora need?
- A minimum of 18 gallons is recommended for the Blue-lined Rasbora.
- What water parameters does the Blue-lined Rasbora need?
- The Blue-lined Rasbora does best with a temperature of 70–79°F, a pH of 5–7.5, hardness around 2–10 dGH.
- Is the Blue-lined Rasbora aggressive?
- The Blue-lined Rasbora is generally peaceful and suits a community tank with similarly calm tankmates.
- What does the Blue-lined Rasbora eat?
- The Blue-lined Rasbora is a carnivore. It needs a meaty, protein-rich diet of frozen or live foods.