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Seahorses are one of the most interesting animals you can keep in a home aquarium. The way they look and swim is fascinating and, whether you have an appreciation for aquatic animals or not, most people will agree they are a bit mysterious and almost unearthly creatures. In some cultures, Seahorses embody a mystical symbolism and have fascinated humans for millennia. The scientific name “Hippocampus” actually comes from a Greek and Roman mythological creature.

Perhaps, exactly why keeping them in an aquarium is something so many of us desire.  As with any pet, it is critical to gather information and do your very best to provide a stable, healthy habitat for the pets in your care. Seahorses are no different, and in fact, can be great aquarium inhabitants if care is given to their specialized needs.

Where To Get A Seahorse

Captive-bred seahorses are 100% the best option for sourcing a seahorse to keep at home. Captive-bred animals are healthier and already accustomed to life in an aquarium. They will be easier to feed aquarium foods and will be less likely to fall victim to disease or infections.

Wild-caught seahorses should be left to the professionals in 99% of cases.  Should you attempt to keep a wild-caught seahorse, take the proper precautions for quarantine and ensure your ability to meet their specialized feeding requirements.  

When searching for a responsible source for horses, it is important to do some research and speak with others in the aquarium community. Joining a forum is a great way to get in touch with experienced horse whisperers. There are a few reputable websites here in the U.S. that sell Seahorses direct to the public. A quick Google search for "captive-bred seahorses" will point you in the right direction and be sure to talk directly with the company to get advice about the specific animals you are interested in keeping.

While most all of the species available to aquarists require identical care, be sure to talk with the breeders or the supplier directly to inquire about specialized needs. 

Common Tropical Seahorses For Aquariums:

  • Lined Seahorse - H. erectus
  • Spotted Seahorse - H. kuda
  • Longsnout Seahorse - H. reidi
  • Tiger-tail Seahorse -   H. comes
  • Barbour's seahorse - H. barbouri  

These are just the most commonly available captive-bred species, there are other cold-water and sub-tropical species and even dwarf seahorses that occasionally pop up for sale in the aquarium trade.

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Read Article: Secrets For Success: Rules You Should Follow To Keep Your Seahorse Aquarium Thriving to learn more about keeping seahorses happy and healthy inside an aquarium. 

It's A Horse Of Course! 

Ok maybe not... they are not even remotely related to terrestrial horses. They do, however, share a similarly shaped head and neck which is why humans have adopted the common name seahorses. All 54 of the individual species known to science stay generally small with the largest growing no more than 12" tall and the smallest being only just 1 cm tall. 

They have prehensile tails that allow them to grasp onto corals, algae, and seaweed because they are not the most powerful of swimmers, at least not when up against the ocean's currents. Seahorses are typically found in or around coral reefs, seagrass beds, mangroves, and estuaries where water currents are mild and plenty of natural structure/cover is available to avoid predators. They are closely related to Pipefish and are a “Bony Fish,” but have skin (instead of scales) which does make them susceptible to certain infections in the aquarium, but more on that later.

A seahorse's reproduction is an exceptionally fascinating process. Contrary to a majority of fish species in the ocean, seahorses form close-knit male-to-female bonds with a courtship ritual that occurs where the female actually transfers eggs into the male's brood pouch. The eggs are then internally fertilized and the male will carry out the gestation and give birth to a group of tiny, living, water-kicking seahorses. The male's elongated torso containing the brood pouch along the front side of the tail has clearly evolved for this and is actually the best way to easily sex a pair of horses.

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Seahorse Aquarium Husbandry

Most successful Seahorse aquariums are species-specific meaning the tank is built for them.  Not to say they cannot be kept alongside other animals, you just have to provide them with the specific care to be successful. Avoid housing with stinging corals and certainly other aggressive fish. The idea is to keep small, peaceful animals that will not be aggressive nor create serious competition for food. Of course, water quality is of utmost importance, so don't overstock your seahorse tank...or really any aquarium for that matter. 

Seahorse Compatible Tank Mates:

  • Snails and hermit crabs
  • Starfish
  • Shrimp
  • A. ocellaris or A. percula Clownfish (with caution)
  • Gobies
  • Dragonettes
  • Pipefish
  • Cardinalfish
  • Blennies
  • Basslets
  • Jawfish
  • Dartfish

Approach tank mates with caution, for example, a pair of mature clownfish can become problematic as the female becomes more and more territorial.  Some Blennies and Gobies are territorial and can be persistent enough to stress out a pair of horses. If you notice feuds among the tank mates, it's best to remove the aggressor before the problem worsens. Fish have personality and no two fish are the same, one fish of the same species may be peaceful while another is downright mean. 

Always keep a pair of seahorses with a minimum tank of at least 30 gallons. They can be kept in groups with roughly 10 more gallons per additional pair of horses. Keeping in pairs and small groups helps to reduce stress. They are vertically oriented as they swim about so choose a tall aquarium measuring a minimum of 18" tall.  You want the tank to have plenty of "hitching posts" which can be live gorgonians or macroalgae or artificial decor like fake plants, branching coral, or plastic chains work well too. It is safe to use live rock, just be sure to avoid anemones, aggressive inverts, and other stinging corals.

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Flow & Lighting

With plenty of hitching posts, seahorses can handle medium to lower flow tanks just fine. Just be sure to turn off the pump and filtration when feeding. Smaller, enclosed powerheads are ok along with the flow from your return pump.  Horses do not have any special lighting requirements, just be sure to provide a natural day/night cycle.  

Filtration

You do need to keep the water clean, so proper filtration and maintenance are absolutely necessary.  If neglected, elevated nutrients can harbor infections among the horses along with a variety of other ailments. A protein skimmer, efficient mechanical filtration, and any necessary media are safe for use with seahorses. All-In-One tanks or smaller tanks with hang-on filtration can work out great, just keep up with maintaining the filtration and don't overstock it.

Seahorses need to be fed often, so often that you're going to end up with an excess of leftover food.  You will need to swap out your mechanical filtration quite often, almost daily. Be mindful of this and be sure leftover food is always removed within a reasonable timeframe. 

A water change schedule is required to keep the nutrients under control and maintain stable pH, temperature, and salinity. If keeping corals, be mindful of their water requirements too. In a seahorse tank, temperature, salinity, and pH are going to be your critical parameters.

Recommended Seahorse Water Parameters

  • Salinity / Specific Gravity: 33 - 35 ppm or 1.020-1.025 SG
  • pH: 8.1-8.4
  • alkalinity: 8-12 Dkh
  • Ammonia (nh3): Undetectable 0 ppm
  • Nitrite (no2): Undetectable 0 ppm
  • Nitrate (no3): Low <20 PPM
  • Phosphate (PO4): Low <0.2 PPM
  • Calcium (Ca): 350-450 PPM
  • Alkalinity (dKH): 8.0-8.3 dKH
  • Magnesium (Mg): 1250-1350 PPM

Most seahorses available to hobbyists are going to be tropical meaning tropical water temperatures are necessary. Should you source sub-tropical, temperate, or cold-water horses, the only difference in care is going to be the temperature ranges outlined below in most cases. 

  • Tropical: 71-74° F
  • Sub-tropical: 67-70° F
  • Temperate: 64-66° F

Reference our reef tank parameters chart to learn more about reef aquarium water parameters.

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Food & Feeding

Proper feeding is one of the most important parts of keeping a seahorse healthy. Offer high-quality frozen or live foods 2-3 times per day at a very minimum, more often if possible. They eat slow and deliberate, therefore you may need to develop of feeding routine in order to successfully deliver the necessary nutrients to all of your horses.  The good news is they can be trained to use a feeding station, you just have to be persistent. These trained feeding behaviors are the best approach to keeping seahorses successfully in the long term because it means they are able to obtain sufficient nutrition. 

High-quality frozen mysis shrimp is the optimal primary food choice with spirulina enriched brine shrimp being suitable as well. They may also eat oyster eggs, fish eggs, and a variety of other small-particle-size, specialty frozen foods. Live foods such as brine, amphipods, and ghost shrimp are also safe to offer. Just remember, the food has to fit into their small mouth and snout but also has to be big enough so that they can see it and catch it.

Always defrost the food in a small container of tank water first.  Proceed to feed the aquarium using a bulb syringe, tube feeder, or feeding station. Leftover food should not be left in the aquarium longer than 30 minutes.