Can you own a Seahorse?

Yes! Anyone can own a Seahorse!

Owning a seahorse has become an increasingly manageable hobby due to advances in aquarium technology. A common question among aquarists is “Can you own a Seahorse?” The confusion behind this question is rooted in a lack of information about Seahorses. In this article, we will discuss the aquarium requirements for owning a Seahorse as well as the process for adding a Seahorse to your fish tank.

A seahorse requires a few things to survive in an aquarium, some specific types of seahorses require additional accommodation so it is important to do research about the type you intend on purchasing.

To own a seahorse, you will need at a minimum the following items:
  • An 18-inch or higher aquarium. The more vertical height the better. 30 Gallons or above is preferred, but you can get away with as little as 20 gallons if you are very diligent about aquarium maintenance.
  • A Hang-On-Back filter rated 1.35x or higher than your aquarium size.
    • (Size in Gallons) x (1.35)
  • Low-Flow powerhead or small protein skimmer.
  • Regular access to RO Saltwater (An RO filter and salt mix can be purchased, or you can buy RO saltwater at a local fish store)

Choosing a Seahorse

Choosing a Seahorse that matches your needs and preferences is the most important part of the process. Some Seahorses require high maintenance (frequent feedings and water checks/changes) while others may not be suitable for other species you would like or already have in your tank.

Lined Seahorse

The lined Seahorse (also known as Hippocampus Erectus) is by far the most popular Seahorse choice for aquarium enthusiasts. Lined Seahorses are among the hardiest choice for an aquarium. This means Lined Seahorses will be most resistant to water chemistry changes.

Lined Seahorses can grow up to 8 inches in length and live for anywhere between 1 and 4 years. They prefer water temperatures between 72 and 78 degrees Fahrenheit and a pH in between 8.1 and 8.4.

These Seahorses are also a great choice for a first Seahorse because captive bred and raised Seahorses of this species are readily available. Wild-caught or raised Seahorses are more likely to pose difficulties during the adjustment process. Wild-caught Seahorses are also not sustainable for the environment.

Dwarf Seahorse

Dwarf Seahorses (also known as Hippocampus Zosterae) are another common choice among Seahorses for aquariums. Dwarf Seahorses are a common choice due to their small size which allows them to be kept in tanks as little as 10 gallons.

Dwarf Seahorses can grow up to 2 inches in length and live for up to one year. Dwarf Seahorses prefer water temperatures between 72 and 78 degrees Fahrenheit and a pH between 8.1 and 8.4.

While Dwarf Seahorses are not as readily available bred in captivity, it is encouraged to take the time to find a sustainable source who does breed in captivity. As mentioned above, wild-caught Seahorses have a much lower success rate and the harvesting process degrades their ecosystem.

Caring for a Seahorse

Caring for Seahorses is generally a tougher process than that of fish. When a Seahorse consumes food, it is digested and processed fairly quickly. This means two things:

  1. Frequent Feedings – Some Seahorses require feedings up to 3 times a day. The specific type of Seahorse will determine the frequency of feedings
  2. Diligent Water Maintenance – This quick digestive tract also means food does not get digested efficiently. Seahorses excrete more waste than fish because of this inefficient digestive process. Excess waste means excess nutrients in the water, and along with this comes diligent water testing and water changing to make sure nutrient levels remain acceptable


Once your Seahorse has adjusted and gotten comfortable in their new home, they will accept a generous variety of foods. Some Seahorses may be stubborn with what they eat in the beginning until they comfortably adjust.

Live Feeding
Live food for Seahorses infographic
  • Mysis Shrimp – Mysis Shrimp make up a significant portion of Wild Seahorses diet. While these little crustaceans aren’t technically Shrimp, newborns are a great feed for Juvenile Seahorses coming off of Baby Brine Shrimp
  • Baby Brine Shrimp – Baby Brine Shrimp are a better source of nutrition than their older counterparts due to a yolk reserve the Baby Brine carry when they are newborn. Baby Brine Shrimp are a coomon live feed used for Dwarf Seahorses as well as juvenile or fry Seahorses
  • Red Shrimp – Red Shrimp are known for their well acceptance among Seahorses. Very few Seahorses will refuse to eat Red Shrimp. Whle these shrimp are harder to come by due to the slow reproduction process, they provide great nutritional value reliably.
Frozen Feeding
Frozen food for Seahorses infographic
  • Mysis Shrimp – Mysis Shrimp make up a significant portion of Wild Seahorses diet. While these little crustaceans aren’t technically Shrimp, newborns are a great feed for Juvenile Seahorses coming off of Baby Brine Shrimp
  • Plankton – Plankton, usually small sized krill, are another common frozen food for Seahorses. Small Krill may have a harder shell than Mysis Shrimp, meaning some Seahorses might be a little more picky with these.
  • Krill – Krill that can be found in a reasonable size (Brands like SFBB) are great for larger species of Seahorses such as a fully grown Lined Seahorse
  • Copepods – Copepods are little crustaceans found in nearly every freshwater and saltwater habitat. These small critters are a good alternative for Seahorse fry who refuse to eat anything else.

Water Maintenance

Caring for Seahorses can be a little different from caring for fish because the Seahorses are tad bit more sensitive to changes in water composition/chemistry. Being diligent about water changes and tests is crucial in caring for a healthy Seahorse.


Seahorses have primitive gills that are not efficient at pulling oxygen from their environment (water). This means dead zones (areas in the tank with very little oxygen) can kill Seahorses much quicker than fish. Dead zones are created by areas of the tank not having much if any flow.

Things can be tricky with Seahorses because they require consistent and homogenous oxygen, but also do not respond well to high amounts of circulation. This is why earlier in the article we mentioned a HOB (hang on back) filter rated 1.35x higher than the gallons in your tank. This, coupled with a small protein skimmer, keeps water moving but not too fast.

Water Changes

As mentioned earlier, Seahorses produce slightly more waste than fish. This is especially true in the first few months of owning a Seahorse because they have yet to adjust to a new feeding regiment. This means having Seahorses in your tank will cause ammonium levels to rise higher than you would expect with fish only.

Through a multi-step nitration process, this ammonia is turned into nitrate. Nitrates are not nearly as toxic to marine animals as ammonium and we remove nitrates by periodic water changes or sometimes the right combination of plants can do the trick.

Seahorses will require a 10% water change every two weeks for the first 3 months. During these 3 months it is important to check water chemistry regularly to make sure everything is in balance. After the first 3 months, the 10% water change can be performed every month. In aquariums with other fish as well, continuing 10% water changes every two weeks should be considered.


During the first 3 months while water changes are being performed more regularly than usual, it is important to regularly check water chemistry. Things like pH, salinity, nitrates, phosphates, nitrites, ammonia, alkalinity, and hardness.

While salinity, ammonia, and pH should be checked bi-weekly in the first month, Alkalinity, hardness, nitrates, nitrites, and phosphates can be checked less often .

High amounts of phosphate may call for an addition of GFO (Granular Ferric Oxide) to your filter or sump. High levels of salinity require water changes with RO Saltwater of lesser concentration than what is currently in your tank.

If your aquarium has high levels of nitrites or ammonia, the pH should be evaluated and adjusted accordingly. In a fish tank with healthy water chemistry, ammonia should be nonexistent and nitrites should be turned to nitrates quickly.

More of a Visual Learner?

ReefMan created an awesome Youtube video about Seahorse tank setup, feeding, and care. If you have the time, stick around a give it a quick watch!

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