Patagonian seahorse (Hippocampus patagonicus)

Classification (WoRMS)

Full classification as recorded by WoRMS: Kingdom: Animalia · Phylum: Chordata · Class: Teleostei · Order: Syngnathiformes · Family: Syngnathidae · Genus: Hippocampus.

Accepted name: Hippocampus patagonicus · Authority: Piacentino & Luzzatto, 2004 · Taxonomic status: accepted · AphiaID: 275205.

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=275205 (CC BY 4.0). Accessed 2026-09-25.

Biology and life history (FishBase)

Measured values published by FishBase for Hippocampus patagonicus. Only fields the database actually holds for this species are shown; these are database values, not aquarium guidance.

Maximum length: 9.199999809265137 cm · Depth range: 0–120 m · Habitat zone: benthopelagic · Body shape: other · Vulnerability index: 10 of 100 · Aquarium trade: never/rarely.

Source: FishBase species summary (SpecCode 62875) — https://www.fishbase.se/summary/Hippocampus-patagonicus.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-25.

Distribution and occurrence records (GBIF)

108 georeferenced occurrence records for Hippocampus patagonicus are published through GBIF from 3 countries or marine areas. The map above plots 18 distinct locations from a sample of 108 records, omitting 12 inland records that carry an institution's coordinates rather than a collection site; it shows where the species has been observed and reported, not a modelled range.

Most records by country or area: Argentina (90); Brazil (11); Uruguay (7).

Source: GBIF Occurrence Search (taxonKey 5201048) — https://www.gbif.org/occurrence/search?taxon_key=5201048&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=275205 (CC BY 4.0); Natural Earth 110m basemap — https://www.naturalearthdata.com/ (public domain). Accessed 2026-09-25.

Conservation status (IUCN Red List)

The IUCN Red List assesses Hippocampus patagonicus Piacentino & Luzzatto, 2004 as Vulnerable (code VU). No trend, population estimate or threat analysis is given here, because none is available from this source without the Red List API; follow the source link for the full assessment, including its date.

Source: IUCN Red List of Threatened Species (taxon 195100) — https://www.iucnredlist.org/species/195100/0; GBIF IUCN Red List category endpoint (taxonKey 5201048) — https://api.gbif.org/v1/species/5201048/iucnRedListCategory. Accessed 2026-09-25.

Description and natural history (Wikipedia)

H. patagonicus is typically 6-15 cm long with low spines, a short snout, and a long tail. Its coronet is a low ridge or wedge. Individuals are drably coloured, ranging from pale to dark brown, yellow, red or orange. The body and head have irregular dark striations and small white dots.

Habitat

H. patagonicus typically occurs in shallow waters to depths of 15 m in Argentina. Individuals in Brazil have been found in deeper waters to depths of 120 m. They are usually found attached to floating marine algae (Sargassum sp.), seagrasses, sessile invertebrates (such as sponges, ascidians and polychaete worms), or artificial substrates.

Feeding

Individuals of this carnivorous species are opportunistic predators, meaning that they prey on whatever species is most abundant and vulnerable in their environment at the time. They prey on amphipods, (including Gammaridae, Caprellidae, and Hiperidae species), and decapods. All sexes and sizes share feeding habits.

Reproduction and growth

H. patagonicus is an ovoviviparous species, with females using an ovipositor to transfer eggs into a male's brood pouch, where they are fertilized and protected until the male gives birth to live young. Average gestation time is 19.6 days, and average brood size in captivity is 207 individuals.

Offspring size is 0.7 cm. Both males and females appear to reach maturity during their first breeding season (spring and summer), at sizes around 11 cm. Life expectancy for H. patagonicus is two to three years.

In San Antonio Bay, juveniles have been reported to demonstrate dispersive potential by rafting, which may explain records of the species in deeper waters. Rafting occurs when juveniles attach to floating substrates, which are then dispersed by currents. This increases the juveniles' dispersal range, but it may also be cause for conservation concern, as rafting juveniles are susceptible to being trapped in seine nets.

Population

There have been no dedicated population surveys or estimates for this species, but inferences based on declining habitat quality, extent of occurrence, and fisher interviews propose a population decline of at least 30% over 10 years.

The major threats to H. patagonicus are fishing pressure and habitat degradation. In both Brazil and Argentina, seahorses are collected and traded as curios, traditional medicines, religious amulets and as aquarium fishes. H. patagonicus is the most commonly caught seahorse species in the south and southeast regions of Brazil, usually as by-catch of shrimp fisheries. Habitat degradation by coastal urban development, shrimp fisheries, and vessel traffic also poses a threat to this species.

All Hippocampus species are listed under Appendix II of the Convention on International Trade in Endangered Species (CITES), which regulates the legal import and export of seahorses. In 2004, the Brazilian Institute of Environment and Renewable Natural Resources implemented an unenforced and unmonitored seahorse export quota of 250 specimens per species. Quotas were clearly violated by exporters, however, who misidentified or mislabeled seahorse species in order to increase exports.

H. patagonicus has been declared a "Natural Monument" in Mar del Plata, Argentina. This is the highest conservation status available in Argentina, prohibiting any abuse, harm, capture or captivity of the species. Exceptions are made in the case of individuals collected for scientific purposes. H. patagonicus is considered a flagship species in Mar del Plata and is used to educate the community about the importance of coastal ecosystems.

Source: Wikipedia: Hippocampus patagonicus — https://en.wikipedia.org/wiki/Hippocampus_patagonicus (CC BY-SA 4.0). Accessed 2026-09-25.