HomeFish encyclopediaRay-finned fishesScorpionfishes and FlatheadsFlatheadsFreespine flathead Freespine flathead (Ratabulus diversidens) Scientific name: Ratabulus diversidens McCulloch, 1914 The Freespine flathead (Ratabulus diversidens) is a marine fish of the family Platycephalidae. Native range: Indo-West Pacific, Eastern Australia. BiologyDorsal spines (total): 10; Dorsal soft rays (total): 10-11; Anal spines: 0; Anal soft rays: 12. This species is distinguished by the following characters: 80-93 anteroventrally slanted oblique scale rows above lateral line; snout length 29.5-32.3% HL, slightly decreasing proportionally with growth; pectoral fin length 13.9-15.8% SL; pelvic fin length 22.1-28.5% SL; nasal bone with tubercles in larger specimens; dorsal surface of head with large, pale to dark-brown irregularly shaped spots, body without spots dorsally; pelvic fin with large brown spots.Source: FishBase, licensed CC BY-NC 4.0. Species factsScientific nameRatabulus diversidensFamilyPlatycephalidae (Flatheads)OrderScorpaeniformes (Scorpionfishes and Flatheads)ClassActinopterygii (Ray-finned fishes)Maximum length39.1Depth range30–345 m (98–1132 ft)EnvironmentMarine; demersal; depth range 30 - 345 mClimateSubtropicalDistributionIndo-West Pacific: Eastern Australia.Conservation status (IUCN)Not EvaluatedThreat to humansHarmlessResilienceHigh, minimum population doubling time less than 15 months (Preliminary K or Fecundity.) SourcesTaxonomy, distribution and biology data: FishBase (Froese, R. and D. Pauly, eds.), licensed CC BY-NC 4.0.Last updated 27 September 2026