Orange-Finned Spiny Eel

This specialist trade import from Indonesia stands out among spiny eels for its unusually warm orange colouration in the fin membranes and lateral body flanks, a characteristic that distinguishes it clearly from the more subdued brown and cream tones of most Mastacembelus species. Its identity is unresolved and it may represent an undescribed species from Sumatra or Borneo.

Due to its rarity and likely blackwater origin, it benefits from soft, slightly acidic water with tannin supplementation via peat or dried leaf litter. A dark substrate will enhance its orange colouration most effectively. Strong filtration and deep fine sand are essential as with all Mastacembelus.

Earthworms are the ideal primary food; prawns and frozen bloodworm add variety. Its rare availability means that specimens should be acquired and housed thoughtfully. It is peaceful toward large robust tankmates in a Borneo or Sumatra blackwater biotope context but will consume smaller fish. A species-appropriate Indonesian setup with this eel as the centrepiece is genuinely impressive.

Water: Soft and slightly acidic, pH 6.0–7.0, temperature 24–28°C, GH 1–8, KH 0–3. Tank: Minimum 200 L, blackwater conditions, dark substrate, deep sand, sealed lid. Feeding: Carnivore; earthworms preferred, prawns, bloodworm, and sinking pellets. Breeding: Not documented in captivity. Compatibility: Peaceful with large robust Indonesian biotope fish; predatory toward small species.