HomeFreshwater aquarium fishOther freshwater fishBig-belly seahorse Big-belly seahorse (Hippocampus abdominalis) Scientific name: Hippocampus abdominalis Lesson, 1827 The Big-belly seahorse (Hippocampus abdominalis) is a brackish-water fish of the family Syngnathidae. BiologyFound in large rock pools at low tide. They remain motionless amidst seaweed. Juveniles are pelagic or attached to drifting seaweeds. Feed on minute crustaceans (e.g. copepods and amphipods). Nocturnal. Ovoviviparous. The male carries the eggs in a brood pouch which is found under the tail. Seen in groups at night. Also around jetties and other man-made objects; attached to sponges and colonial hydroids in deeper water. Length measurements refer to height (= TL - head length).This is the largest seahorse species in southeastern Australia, and has more dorsal fin rays and tail rings than any other seahorse. Sold locally and internationally for the aquarium trade. Dried and sold to the Oriental medicine trade as a tonic and aphrodisiac.Source: FishBase, licensed CC BY-NC 4.0. Species factsScientific nameHippocampus abdominalisFamilySyngnathidae (Pipefishes and seahorses)OrderSyngnathiformes (Pipefishes and Seahorses)ClassActinopterygii (Ray-finned fishes)Maximum length35.0Common length18.0Depth range0–104 m (0–341 ft)EnvironmentMarine; brackish; demersal; non-migratory; depth range 0 - 104 mClimateTemperateDistributionSouthwest Pacific: Australia and New Zealand. Vulnerable. Occurrence in Thailand and the Philippines needs verification. International trade is monitored through a licensing system (CITES II, since 5.15.04) and a minimum size of 10 cm applies.Conservation status (IUCN)Data deficient (DD)Threat to humansHarmlessUsesFisheries: of no interest; aquarium: commercialResilienceHigh, minimum population doubling time less than 15 months (tm=1; Assuming annual Fec More other freshwater fishLined soleAchirus lineatusPumpkinseedLepomis gibbosusShort-tailed pipefishMicrophis brachyurus brachyurusFinescale tigerfishDatnioides microlepisFreshwater garfishXenentodon cancilaSouth American lungfishLepidosiren paradoxaSee all other freshwater fish SourcesTaxonomy, distribution and biology data: FishBase (Froese, R. and D. Pauly, eds.), licensed CC BY-NC 4.0.Last updated 27 September 2026