Orthogoniata River Loach

Homaloptera orthogoniata is one of the more striking Homaloptera species, bearing angular, sharply defined dark saddles and blotches on a pale body that recall the bold graphic markings of some doradid catfish. It is native to the fast-flowing hill streams of Borneo, occurring in the same high-energy, clear-water environments as many Gastromyzon species, though it tends to occupy slightly deeper and faster zones where its larger, more streamlined body is advantageous.

In aquaria, H. orthogoniata requires a spacious tank of at least 120 litres to accommodate its more active swimming style. Strong, directional flow is essential and should be concentrated along the substrate surface. Like most Homaloptera, it is an omnivore and will accept a wider variety of prepared foods than strictly herbivorous hillstream loaches, making feeding somewhat simpler.

The species is not commonly captive-bred and most available specimens are wild-caught imports. These should be carefully quarantined and observed for signs of parasites common in wild-caught loaches, including camallanus worms and external protozoa. Once established, H. orthogoniata is a long-lived and rewarding species.

Water: 22–26°C, pH 6.0–7.0, GH 3–12, KH 1–6; powerful, directional flow along the substrate; fully saturated dissolved oxygen at all times. Tank: 120 L minimum; large smooth boulders, open gravel sections, and powerful powerhead or sump-return flow creating current channels. Feeding: Omnivore — algae wafers, sinking pellets, frozen bloodworm, daphnia, and shrimp; will also graze biofilm from rock surfaces. Breeding: Not documented in captivity; treat as wild-only species for now; condition with increased flow and slight temperature reduction. Compatibility: Peaceful; best with other Bornean hillstream species or medium-to-large cool-water community fish; avoid small nano species.