Ridens Gastromyzon

Gastromyzon ridens takes its name from the Latin for 'laughing', a reference to the peculiar curve of its mouth profile which, when viewed from the front, gives the fish an expression of perpetual amusement. It is native to hill streams in Sabah, Malaysian Borneo, and is only occasionally imported for the aquarium trade, making it a sought-after species among collectors. Its patterning is on the finer, more reticulated end of the Gastromyzon spectrum, with intricate dark markings on a warm buff background.

In the aquarium, G. ridens has the same fundamental requirements as other Gastromyzon — fast flow, well-oxygenated cool water, smooth substrate, and a diet based around biofilm and algae. Due to its rarity and limited captive breeding, wild-caught specimens dominate the trade and must be carefully quarantined and acclimated before introduction to a display tank.

This species is best kept with other moderate-to-advanced hillstream species in a dedicated biotope aquarium. Its rarity and specific requirements make it unsuitable as a casual purchase, and prospective keepers should research and prepare the aquarium thoroughly before acquiring specimens.

Water: 22–26°C, pH 6.0–7.0, GH 3–12, KH 1–6; high dissolved oxygen and moderate to strong flow essential at all times. Tank: 70 L minimum; smooth rounded stones and flat rocks for grazing; dim lighting with heavy algae growth on surfaces is ideal. Feeding: Biofilm and microalgae; supplement with spirulina wafers and blanched vegetables; wild-caught fish may initially refuse prepared foods. Breeding: Very rarely achieved in captivity; quarantine wild imports thoroughly before attempting to breed; condition as per other Gastromyzon species. Compatibility: Peaceful; best kept as part of a specialist hillstream biotope with other Gastromyzon or Sewellia species.