Black-finned Stiphodon Goby

Stiphodon percnopterygionus is named for its most striking feature: the intensely black-pigmented fins (percno = dusky/black, pterygion = fin) of mature males, which contrast dramatically with their metallic body colouration. Males display a complex pattern of electric blue, green, and orange iridescence on the body alongside the characteristic jet-black fins, making this species one of the most visually striking freshwater gobies available to the aquarist. It is native to the fast, clear hill streams of Taiwan and the Ryukyu Islands of Japan.

As with all Stiphodon, S. percnopterygionus is an amphidromous species whose larvae spend an early phase in the sea before migrating upstream. This life history means captive breeding is not feasible in standard freshwater aquaria, and all available trade specimens are wild-collected from Taiwan or Japanese export sources. These fish should be quarantined carefully and the supply chain verified before purchase.

In the aquarium, conditions must be clean, fast-flowing, and well-oxygenated. The species requires slightly cooler temperatures than some Pacific Stiphodon species and prefers moderately hard, neutral to slightly alkaline water reflecting its island stream habitat. Males will display aggressively toward other male Stiphodon, spreading fins and flaring at rivals across territorial boundaries.

Water: 20–26°C, pH 7.0–8.0, GH 6–18, KH 4–12; strong flow and very high dissolved oxygen; moderately hard water reflects Taiwanese island stream chemistry. Tank: 60 L minimum; smooth rounded boulders with established microalgae; powerful powerhead creating strong unidirectional flow; no stagnant zones. Feeding: Herbivore — microalgae and biofilm; supplement with spirulina wafers and algae gel food; very little dietary protein required. Breeding: Amphidromous life cycle; captive breeding requires marine larval facilities; not currently achievable in standard freshwater aquaria. Compatibility: Males aggressive toward other male Stiphodon; peaceful toward unrelated species; best kept as one male with one or two females.