Lined seahorse (Hippocampus erectus)

Classification (WoRMS)

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

Accepted name: Hippocampus erectus · Authority: Perry, 1810 · Taxonomic status: accepted · AphiaID: 159445.

Synonyms and superseded combinations recorded for this taxon: Hippocampus brunneus Bean, 1906; Hippocampus fascicularis Kaup, 1856; Hippocampus hudsonius DeKay, 1842; Hippocampus kincaidi Townsend & Barbour, 1906; Hippocampus laevicaudatus Kaup, 1856; Hippocampus marginalis Kaup, 1856; Hippocampus punctulatus Guichenot, 1853; Hippocampus stylifer Jordan & Gilbert, 1882; Hippocampus tetragonous (Mitchill, 1814); Hippocampus villosus Günther, 1880; Syngnathus caballus Larrañaga, 1923; Syngnathus tetragonous Mitchill, 1814.

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=159445 (CC BY 4.0). Accessed 2026-09-23.

Biology and life history (FishBase)

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

Maximum length: 19 cm · Depth range: 0–100 m · Habitat zone: reef-associated · Body shape: other · Vulnerability index: 31.2 of 100 · Fishery importance: minor commercial · Aquarium trade: commercial.

FishBase notes: Generally in coastal waters; often around man-made structures (Ref. 26938). Usually attached to gorgonians or seagrasses but may occur in floating Sargassum or swimming freely in midwater (Ref. 9710). Those that live in Sargassum usually have bony protuberances and fleshy tabs that may serve as camouflage. Has been reared in captivity (Ref. 35420, 35422). Move into deeper waters during winter (Ref. 36630). Feeds by sucking in small organisms, using its long face as a pipette (Ref. 26938); like small crustaceans (Ref. 27549). Ovoviviparous (Ref. 205). The male carries the eggs in a brood pouch which is found under the tail (Ref. 205). Length type refers to Height (= from top of coronet to the tip of straightened tail).

Source: FishBase species summary (SpecCode 3283) — https://www.fishbase.se/summary/Hippocampus-erectus.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-23.

Distribution and occurrence records (GBIF)

18,783 georeferenced occurrence records for Hippocampus erectus are published through GBIF from 42 countries or marine areas. The map above plots 107 distinct locations from a sample of 3,000 records, omitting 62 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: United States of America (17,973); Puerto Rico (446); Mexico (87); Canada (61); Bermuda (36).

The full country table, WoRMS marine regions and the sampling notes are on this species' Distribution page.

Source: GBIF Occurrence Search (taxonKey 5201075) — https://www.gbif.org/occurrence/search?taxon_key=5201075&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=159445 (CC BY 4.0); Natural Earth 110m basemap — https://www.naturalearthdata.com/ (public domain). Accessed 2026-09-23.

Conservation status (IUCN Red List)

The IUCN Red List assesses Hippocampus erectus Perry, 1810 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 10066) — https://www.iucnredlist.org/species/10066/0; GBIF IUCN Red List category endpoint (taxonKey 5201075) — https://api.gbif.org/v1/species/5201075/iucnRedListCategory. Accessed 2026-09-23.

Description and natural history (Wikipedia)

Lined seahorses feed mainly on minute crustaceans and brine shrimp, which they suck in through their snout. They are able to suck their prey by creating a current of water leading directly into its snout. Since seahorses are weak swimmers, they must ambush their prey by blending into their surroundings, which they do rather easily. The lined seahorse's eyes can move independently of one another, allowing it to effectively scan its surroundings. The species is sexually dimorphic and it is easy to distinguish between a male and female lined seahorse. The males are larger and also have longer tails. The lined seahorse is monogamous and performs ritual dances every morning to reestablish the bond with its mate. In addition, they create clicking sounds while embracing their partner. This action occurs when they initially find their mate. The intensity of their bond is also conveyed in how they handle the death of their partner: If either the male or female should die, the mate does not automatically replace the deceased mate with a new one. Often, it fails to find a new mate in its short lifespan.

Like with other seahorses, the male lined seahorse is the caregiver. During intercourse, the female sprays her eggs into the male's brood pouch where the eggs will incubate for 20–21 days. When the juveniles are ready to hatch, the male attaches its tail to a stationary structure and begins to arch its back, back and forth, releasing the juveniles into the water column. The juveniles are approximately 11 mm at birth. They quickly begin to learn and mimic the behavior of its parent. Courtship between the male and female parents begins immediately after birth.

The habitat of the lined seahorse is diminishing due to coastal growth and pollution, which ultimately is the cause of the decreasing population. The lined seahorse is also used as Chinese medicine and is common in the aquarium trade, contributing to its "vulnerable" status.

The lined seahorse range spans from the waters to the south of Nova Scotia, to the southern area of Venezuela in South America. They can be found on the east coast of United States in Connecticut, Delaware, Florida, Georgia, Louisiana, Maryland, New Jersey, New York, Rhode Island, Virginia, and the Carolinas, as well as in the waters surrounding Mexico and the Caribbean. Species found in Brazil seem to be of a different species; however, more research is needed to determine this proposal. The lined seahorse is native to the following locations: United States, Bermuda, Cuba, Mexico (Veracruz, Yucatán), Haiti, Saint Kitts and Nevis, Belize, Honduras, Nicaragua, Costa Rica, Panama, Guatemala, and Venezuela. It has also been recorded from the Azores but it is not clear that a population has become established in the waters around that archipelago.

Its habitats are marine intertidal and marine neritic.

The temperature in which the H. erectus dwells varies with the different latitudes. Temperature has an effect on gonad development, brood size, and juvenile development and survival. Many lined seahorses experience temperature fluctuations during the daily tide cycles, the different seasons of each year, and due to precipitation or runoff. Adults have the ability to migrate to deeper waters during cold seasons. A study showed that the highest survival and growth rate of juveniles occurred at 28 to 29 degrees Celsius in captivity. In addition to temperature, there is also a large range of salinity concentration depending on the location that affect the species. The most common salinity is 25 to 35 ppt. In captivity, the species is most commonly kept at 35 ppt. The H. erectus is the only species of seahorse native to the Chesapeake Bay.

The lined seahorse utilizes its elongated snout in order to consume its prey, consisting primarily of minute crustaceans, mollusks, and zooplankton. Unfortunately, some captive parental males have been known to cannibalize small number of its own fry, or juveniles, following its release into natural habitat. In order to ambush its prey, the seahorse employs color changes to camouflage itself with its surrounding environment, locates the prey, and then jerks its head upward, forcing the prey in the right position to be sucked in through its tubular snout. The lined seahorse is highly accurate, especially if its prey is within one inch from its snout. Overall, this process is quick and accurate. A growing lined seahorse may feed continuously for up to ten hours a day, engulfing approximately 3,600 baby brine shrimp.

The predators of the lined seahorse include crabs, rays, skates, seabirds, sharks, tuna, and dolphinfish.

Source: Wikipedia: Lined seahorse — https://en.wikipedia.org/wiki/Lined_seahorse (CC BY-SA 4.0). Accessed 2026-09-23.

In the aquarium (Wikipedia, cited section)

The minimum habitat requirements for captive lined seahorses consist of a tank 18 inches vertical in height and 20 to 25 gallons for a pair, 30 to 40 gallons for two pairs. The tank should be kept at a constant temperature between 22 and 25 degrees Celsius (72 and 77 degrees Fahrenheit). The ph value should remain between 8.1 and 8.4 and the specific gravity between 1.020 and 1.025.

The lined seahorse is an easy going species and will not be a threat to other fish that could possibly be in an aquarium. The seahorse thrives in an environment with objects it can hide around and attach its tail to. The H. erectus species should be fed multiple times throughout the day, rather than less amount of larger meals. In captivity, the lined seahorse is often fed live or frozen nauplius or Mysis shrimp, grass shrimp, adult brine shrimp, gammarids and caprellid amphipods, krill fish fry, and frozen krill.

This block reproduces what the species' own Wikipedia article states about it in captivity, with that article's 8 inline citations. No care parameters — tank size, temperature, reef-safety, temperament — are published by any of the databases used on this page, and none have been added.

Source: Wikipedia: Lined seahorse — section "Aquarium life" — https://en.wikipedia.org/wiki/Lined_seahorse (CC BY-SA 4.0). Accessed 2026-09-23.