Great seahorse (Hippocampus kelloggi) care guide

Group
Marine fish
Other names
Kellogg's seahorse
Family
Syngnathidae (seahorses and pipefishes)
Origin
Indo-Pacific from East Africa to Japan, also northern and southern Australia; coral-rich areas, usually shallow but recorded to 152 m
Water
saltwater
Maximum size
28 cm
Temperature
20–24°C
pH
8.1–8.4
Hardness
Salinity SG 1.023–1.026
Minimum tank
200 litres
Care level
expert
Temperament
peaceful
Reef safe
with_caution

Care

Tank and decor: one of the largest seahorses, so it needs a tall, roomy tank with gentle flow and sturdy hitching posts. Minimum tank: about 200 litres for a pair (an estimate based on its 28 cm adult size). Wikipedia notes that it is hard to buy and to keep because of its size and because it competes poorly for food, which often leads to early deaths; feed it in a species tank where nothing else takes its food. Water: the list marks this species as subtropical. Our sources give no further figures, so the values here are general marine aquarium guidance, not species-specific: 20–24 °C, pH 8.1–8.4 and specific gravity 1.023–1.026. Seahorses are very sensitive to poor water quality and to bacterial infections, so keep the tank clean and well filtered. Behaviour and identification: the list describes it as light tan, with some darker specimens. Wikipedia says it is usually found alone or in very sparse groups. The IUCN Red List assessed it as Vulnerable in 2017. All seahorses (genus Hippocampus) are listed on CITES Appendix II. In Great Britain, CITES Appendix II species are Annex B under the wildlife trade regulations, so sellers must be able to show the fish was legally imported or captive-bred and keep the paperwork. Captive-bred seahorses are strongly preferred: they settle better and usually accept frozen food. Sources: Wikipedia, List of marine aquarium fish species (en.wikipedia.org/wiki/Listofmarineaquariumfishspecies); Wikipedia (en.wikipedia.org/wiki/Greatseahorse). Checked October 2026.

Diet

Feeds on small live crustaceans in the wild. In captivity give enriched frozen mysis shrimp two or three times a day; captive-bred seahorses usually take frozen food readily, while wild-caught ones may need live mysis or enriched brine shrimp at first. Seahorses have no stomach to store food, so they need frequent small meals. Remove uneaten food promptly.

Breeding

Wikipedia reports that males compete for mates and that courtship involves the pair twisting tails and nodding heads. The male carries the eggs in his pouch for a few weeks, then releases the young with no further care, and can often breed again almost immediately. The fry need live food such as rotifers and newly hatched brine shrimp and are best raised separately. Captive breeding is rare.

Compatibility and tank mates

Reef safe with caution: seahorses do not harm corals, but they can be stung by anemones and aggressive corals and may lose out to fast-feeding fish. Keep them in a species tank or with small, calm tankmates such as small gobies and pipefishes. Avoid crabs, anemones, large shrimps and any fish that nips or competes hard for food. They will eat very small shrimps.

Last updated 8 October 2026. Community-edited care guide on Aquatic-Auctions.

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