Japanese Sicyopterus Goby

Sicyopterus japonicus is one of the most ecologically fascinating freshwater gobies in the world. Found in Japan, Taiwan, and the Philippines, it is an obligate amphidromous species whose post-larval juveniles famously migrate upstream from the sea, climbing waterfalls using a unique combination of the pelvic suction disc and the mouth as a second suction organ. In breeding condition, males transform into intensely beautiful fish with a turquoise-blue iridescent sheen covering the entire body, vivid fin colouration, and dramatic display behaviour. This species is a strict aufwuchs grazer and requires a mature biofilm to survive long-term in captivity. Water must be cool, fast-flowing, and highly oxygenated. It is an advanced-level fish that rewards patient, experienced aquarists with one of the most spectacular displays in the freshwater goby world.

Water: 20–26 °C, pH 7.0–7.8, GH 5–15, KH 3–10; very high flow and oxygenation essential; sensitive to organic pollution. Tank: 80 L minimum; natural river cobble and flat rocks arranged to create riffles; mature biofilm on all rock surfaces. Feeding: Strict biofilm and algae grazer; spirulina wafers, Repashy gel foods, and blanched greens; rarely accepts protein-based foods. Breeding: Amphidromous; captive breeding not documented; larvae are marine. Compatibility: Peaceful; compatible with other hillstream species; avoid boisterous or predatory tankmates.