Rhinogobius Flumineus Goby

Rhinogobius flumineus is a well-studied stream goby endemic to central and western Japan, inhabiting clear, moderately fast-flowing rivers and streams over gravel and pebble substrates. It is ecologically important in Japanese river ecosystems and has been the subject of numerous scientific studies on Rhinogobius biology and amphidromous ecology. Males in breeding condition are among the most attractive Japanese Rhinogobius, displaying vivid orange-red spots in a close-set pattern along the flanks, bright blue-green iridescence on the cheeks, and intensely pigmented fins with a dark submarginal band on the dorsal fin. The species is slightly larger than R. similis, reaching up to 7 cm in large males. In the aquarium it is personable, hardy, and easy to feed. It is a dedicated cave spawner, and captive breeding has been achieved on numerous occasions. Best kept at cool temperatures without supplemental heating.

Water: 15–22 °C, pH 7.0–7.8, GH 5–15, KH 3–10; cool water essential; highly sensitive to temperatures above 24 °C. Tank: 60 L minimum; smooth river pebble and flat stone caves; moderate to strong directional flow. Feeding: Carnivore; frozen bloodworm, brine shrimp, daphnia, and small sinking pellets; very enthusiastic feeder. Breeding: Cave spawner; male guards eggs with intensity; fry are amphidromous but some captive breeding success reported. Compatibility: Peaceful; excellent with other cool-water stream species; males display but rarely injure.