Philypnodon macrostomus
Dwarf Flathead Gudgeon
Species Summary
One of Australia’s smallest gudgeons, Philypnodon macrostomus was only formally described in 2006, from Coffs Harbour, New South Wales, having previously been kept and bred under the informal name “Philypnodon sp. 1.” It differs from its larger, more aggressive relative the Flathead Gudgeon (Philypnodon grandiceps) in a narrower gill opening, more vertebrae, a smaller maximum size (around 6 cm compared with 9 cm) and the absence of that species’ thin vertical belly bands, and the two are sometimes found together.
Distribution & Habitat
Philypnodon macrostomus occurs along coastal rivers from the Fitzroy River in Queensland through New South Wales and Victoria to eastern South Australia, with scattered records in the lower Murray River. It tolerates everything from fresh water to full-strength seawater in upper estuaries, and is easily caught by dip-netting through streamside vegetation or scooping slow-flowing water.
Keeping & Caring
Philypnodon macrostomus is an excellent, unfussy community aquarium resident, tolerant of both clear fresh water and muddy, brackish estuarine conditions, and has been kept successfully for over 15 years alongside Empire Gudgeons, smelt, rainbowfish, galaxiids, blue-eyes, glassfish, southern gobies and glass shrimp without any observed aggression. It spends most of its time scavenging along the bottom, prompting comparisons to a miniature Australian equivalent of the popular South American Corydoras catfish. Typically caught at 1–3 cm, it rarely exceeds 3 cm and can live for up to three years in captivity.
Breeding
A first-hand breeding account from wild-caught Brisbane-region fish describes a large male guarding an egg mass roughly 3×4 cm laid on a vertical aquascape surface, fanning it and aggressively displaying with a red-lipped, head-to-head posture towards any intruder. At 19–22 °C, eyespots became visible in the eggs by day 4, the first fry became free-swimming within 12 hours of that, and the whole clutch was free-swimming (6–8 mm) by day 8 — though in that particular attempt, all fry were lost the following day, likely to predation.
Compiled for Home of the Rainbowfish from ANGFA sources: A. Fletcher, “An aquarium spawning of the dwarf flathead gudgeon Philypnodon sp. 1”, Fishes of Sahul 11, 1997, pp. 503–504; D. Shoesmith, “A community hero – the dwarf flathead gudgeon”, Fishes of Sahul 29, 2015, pp. 866–868.