10 Seahorse Tank Mates – List of Compatible Species

Seahorses are deeply fascinating creatures. Their interesting body shape, vibrant colors, and upright posture add a lot of interest to the aquarium.

A lot of people also appreciate seahorses due to their sweet and gentle nature. But a lot of the traits that make seahorses so lovable also make them challenging to keep in a community tank.

This special aquatic pet has special requirements. You must be very careful when choosing its tank mates.

Choosing the Right Seahorse Tank Mates

The species you pick must be compatible with seahorses from multiple points of view. You’ll have to consider various factors such as:

– Temperament and Behavior

Seahorses are mellow and peaceful. They don’t get territorial or compete for food, so their tank mates should have a similar temper.

Seahorses have thin skin and they’re prone to infections. They also have no means of defending themselves against touchy tank mates.

Avoid territorial and semi-aggressive fish that bully other tank mates. Avoid any species that could accidentally hurt the seahorse’s delicate skin. This will predispose them to nasty infections.

– Species Size and Swimming Speed

Seahorses grow up to 5-11 inches, depending on the species. They are also slow swimmers. Their tank mates should be equally slow and of a similar size.

Otherwise, feeding becomes an issue because seahorses can’t compete for food. And seahorses must take in a lot of food due to their short digestive tract.

Starvation sets in quickly when they can’t feed properly.

– Space Requirements

This is not an absolute rule. You can choose species with similar or higher space requirements. You must consider the available aquarium space you have first.

One pair of seahorses should have around 30 gallons of tank space available.

Depending on how much space you have left, the fish you choose can either make or break the space limit.

– Water Parameters

The tank mates you choose must be able to tolerate a seahorse’s ideal environment. Unlike other tropical species, seahorses require cooler water. The ideal temperature is 72-76°F.

This species also requires alkaline water with a pH of 8.1-8.4. The hardness level should be 8-12 dGH and the salinity should measure between 1.020-1.025.

Given all these requirements, most people choose to keep seahorses in a species-only tank. This is the oft-touted recommendation.

Best Tank Mates for Seahorses

But it’s not as difficult as it looks. You can definitely find gentle, slow-moving tank mates with similar space and water parameter requirements.

In fact, I’ve already put together a list in this article!

Without further ado, here are 10 of the most compatible seahorse tank mates:

1. Royal Gramma

The Royal Gramma is among the most eye-catching additions to any community tank. This brightly-colored fish is hardy, easy to care for, and it’s even safe for reef tanks!

This fish is also carnivorous and accepts the same foods that you’d normally feed to your seahorses. Here’s some more information on this species:

• Temperament and behavior: This fish is peaceful and passive. It gets shy around larger tank mates and usually stays out of trouble. However, they can get territorial over certain parts of the tank.

They like to claim rocks and caves as their own. They’ll try to intimidate any fish or seahorse that comes near their spot. Overall, if the aquarium is large enough, this shouldn’t be a problem.

• Size and swimming speed: Royal Grammas grow up to 3 inches long. They aren’t large enough to be a threat to seahorses in the tank. They’re also rather unimpressive swimmers. They don’t compete for food. Instead, they wait for the food particles to float in their direction.
• Space requirements: You’ll need a 50-gallon tank to house a pair of Royal Grammas. You can also keep one single fish in 30 gallons.
• Water parameters: When it comes to parameters, you couldn’t find a better match for your seahorses. This fish requires similar temperatures, roughly 72-78°F. They prefer a pH between 8.1-8.4, a hardness level around 8-12 dGH, and a salinity between 1.020-1.025.

2. Yellow Clown Goby

For those with not enough room to spare, I recommend the Yellow Clown Goby. This bright golden fish is perfect for all aquarium sizes, including nano tanks.

It’s also easy to care for, inexpensive, and highly compatible with most peaceful species, seahorses included!

Even better, the Yellow Clown Goby consumes a very similar diet to what you’d feed your seahorses.

They love brine shrimp, mysis shrimp, and other small crustaceans. They’re excellent tank mates for a variety of reasons:

• Temperament and behavior: The Yellow Clown Goby is a very peaceful and shy little fish. It’s unlikely for this species to cause trouble in a community tank. In fact, quite the opposite!

They’re often victims of bullying due to their size and passive nature. They aren’t very adventurous and prefer spending most of their time close to rocks and corals. That’s where they can hide and be safe.

• Size and swimming speed: This fish grows up to 1.5 inches. Most specimens are around 1 inch long though. These Gobies are small, but not so small that they’ll get accidentally eaten by most seahorses.

Given their size, there won’t be a lot of competition for food between species. While Gobies are pretty quick to flee when threatened, they don’t go out of their way to look for food. Instead, they wait for the food to reach their location, usually via the current in the water column.

• Space requirements: You can keep a breeding pair in as little as 10-12 gallons worth of aquarium space. However, if you want to keep a small group of Gobies, a 30-gallon tank is a safer bet.
• Water parameters: The ideal water conditions include 72-78°F temperature, 8.1-8.4 pH, 8-12 dGH, and 1.020-1.025 SG.

3. Firefish Goby

The Firefish Goby, also known as the Magnificent Dartfish, is a unique-looking species suitable even for small aquariums.

Its gradient red body and humorously tall dorsal fin will draw all of the attention in the tank.

Besides its peculiar appearance, this carnivorous little fish has other perks like being reef-safe, low-maintenance, and space-economical.

It’s also a highly compatible tank mate for your seahorses. Here’s a closer look at this species:

• Temperament and behavior: The Firefish Goby is a peaceful and timid fish. It gets startled easily and needs a bit of time to settle into a new aquarium.

They might become irritated and pushy around other Gobies if there’s not enough room in the aquarium.

Around other fish, invertebrates, and even corals, the Firefish is a total sweetheart. They’re the perfect tank mate in a community tank with other gentle, non-aggressive species.

• Size and swimming speed: This fish grows up to 3 inches in length. It’s still smaller than your average seahorse, so no problems here. However, know that Firefish Gobies are agile swimmers. That’s where the name “Dartfish” comes from.

They can reach an impressive speed for their modest size. Luckily, they only dart around the aquarium when threatened. They move more slowly when hunting for food, giving the seahorses some leeway to feed.

• Space requirements: This species is perfect even for tiny aquariums. You can keep one fish in around 10-12 gallons worth of aquarium space. You’ll have to provide 20 gallons for a breeding pair.
• Water parameters: The ideal values are similar to those of other Gobies. They include 72-80°F, 8.1-8.4 pH, 8-12 dGH, and 1.020-1.025 SG.

4. Banggai Cardinalfish

The Banggai Cardinalfish proves that you don’t need to dress all flashy and colorful to draw attention.

This fish’s mesmerizing appearance is all thanks to its distinct fin shape and simple stripes and pearly white patterns.

Besides its endearing look, this species is also easy to care for and eats a similar diet to carnivorous seahorses.

Their diet focuses on small crustaceans like mysis and brine shrimp. But these two species are compatible in other ways than just food:

• Temperament and behavior: The Banggai Cardinalfish is peaceful around fish and sea creatures with a similar temperament. They don’t go out of their way to harass other tank mates. But they can also stand their ground against semi-aggressive fish.

Luckily, this won’t be the case in a seahorse tank. Banggai Cardinalfish get easily startled and they become stressed when kept alone. This highly-sociable fish should be kept in groups of at least three, preferably with only one male.

• Size and swimming speed: These fish grow up to 3 inches in length. That’s a decent size for a seahorse tank mate. But they’re still not large enough to pose a threat during feeding.

The Banggai Cardinalfish is an average swimmer and an opportunistic feeder. They don’t go out of their way to hunt but will feed on meaty foods brought around by the current in the water column.

• Space requirements: You’ll need roughly 30 gallons worth of space for one fish or a pair. More space is required if you plan to keep a small group.
• Water parameters: This fish has similar requirements to seahorses, but can tolerate a slightly narrower range of salinity. The ideal values include 72-79°F, 8.1-8.4 pH, 8-12 dGH, and 1.022-1.025 SG.

5. Court Jester Goby

The Court Jester Goby gets its name from its distinct body pattern. This fish comes in various shades of blue or green.

It also sports thin, continuous horizontal stripes that traverse all of its body, like a jester costume.

Its personality and non-demanding nature make this fish a perfect choice for many community tanks.

This highly-adaptable little fish can get along well with a variety of fish and seahorse species. Here’s what you need to know about them:

• Temperament and behavior: This Goby species is both gentle and timid. Jester Gobies act peaceful and keep to themselves. They don’t go out of their way to interact with other species in the aquarium.

Instead, they spend most of their time wandering around and nibbling on algae and meaty foods they find in the tank.

They need plenty of hiding spaces to retreat to because they get intimidated easily.

• Size and swimming speed: This fish grows up to 2.5 inches, with most specimens measuring around 2 inches in length. Jester Gobies are small enough not to outswim most seahorses during feeding.

Because they’re so shy, they might require target feeding. Unlike seahorses, Jester Gobies aren’t as adventurous when looking for food.

• Space requirements: This fish doesn’t need that much room. Actually, you can even keep it in a nano-tank, if necessary. You’re going to need around 10 gallons for one Court Jester Goby. Double that if you’re planning to keep a breeding pair.
• Water parameters: The ideal values include 73-78°F, 8.1-8.4 pH, 8-12 dGH, and 1.021-1.023 SG.

6. Nerite Snails

That’s right! Snails! You don’t have to limit yourself just to fish species. And if you want a zero-effort, cheap, and useful addition to your seahorse aquarium, you can’t go wrong with Nerite snails.

These inoffensive critters bother no one, and they spend most of their time feeding on algae. They don’t compete for food, plus they help keep your aquarium clean at the same time!

They also need very little space and care, so they’re perfect even for absolute beginners. Here’s a quick species profile:

• Temperament and behavior: Nerite snails are mellow and peaceful. They show no interest in other species in the tank. Most of the time, they appear to be completely sedentary, blending in with the environment.

They’re guaranteed to cause no trouble in the community tank. You can’t get any safer tank mates than this species.

They don’t even have to compete for food, because they’re completely herbivorous!

• Size and swimming speed: Nerites are tiny. They grow up to 1 inch and that’s it. They’d be quite easy to miss if they blend in with the rest of the decorations!

When it comes to speed, you already know what to expect from a snail. They’re so slow that they appear static. Nothing to see here!

• Space requirements: The best part about snails is that they don’t need much space. You can keep one Nerite snail in just 5 gallons worth of space. If you have a 30-gallon aquarium, you’re looking at six snails you can fit in there.
• Water parameters: They can easily adapt to the conditions in a seahorse tank. Their ideal values include 72-78°F, 8.1-8.4 pH, 6-12 dGH, and 1.020-1.028 SG.

7. Orange Striped Cardinalfish

The Orange Striped Cardinalfish is covered in bright golden-orange horizontal stripes, hence its name. To me, this fish looks like a ray of sunshine, literally.

This species is low-maintenance, highly adaptable, reef-safe, and suitable for all community tanks.

The Orange Striped Cardinalfish will thrive next to its seahorse tank mates. Both species eat similar carnivorous diets and they prefer brine and mysis shrimp.

But most importantly, they have compatible personalities and needs:

• Temperament and behavior: The Orange Striped Cardinalfish is among the friendliest and most peaceful fish you can find. It doesn’t mind sharing a space with other species, and it doesn’t get territorial or competitive.

This tiny fish is very timid around others. It might spend most of its time hiding or keeping to itself. When around members of its species, the Striped Cardinalfish becomes more sociable and active.

• Size and swimming speed: Striped Cardinalfish might grow up to 3 inches long. But most fish top at 2.5 inches. They’re pretty small, to say the least. They’re also slower swimmers and they’re most active during the night.

These facts make feeding a bit difficult in a community tank. Luckily, seahorses are at a similar disadvantage while feeding. These two won’t have to worry about competing for food.

• Space requirements: The good news is that this fish doesn’t need lots of space. About 10 gallons is enough for one fish.

The less good news is that these Cardinalfish are highly sociable. They should be kept at least in a pair. That bumps up the space requirements to 20 gallons.

• Water parameters: The ideal values include 72-78°F, 8.1-8.4 pH, 8-12 dGH, and 1.020-1.025 SG.

8. Pajama Cardinalfish

Pajama Cardinalfish might not sport the brightest colors, but they’re hard to miss in a community aquarium. Their appearance is truly peculiar.

They look like a mix and match of random patterns, including shimmery scales, a mesh-like dark patch on its mid-body, and orange polka dots towards the tail.

Their fins also look like a half-and-half combo of translucent grey and deep yellow. They truly make a statement piece for the aquarium.

But the reason why I put them on the list is their high compatibility! They make a good match for seahorses. And for multiple good reasons:

• Temperament and behavior: Pajama Cardinals are extremely calm and peaceful. They get along well with their own, as well as other species. They might establish a territory where they spend most of their time.

But they don’t become aggressive with other fish who wander around in their space. These fish are also highly sociable and mostly active during the night. They spend most of their time with other Cardinals and only venture around the aquarium when the lights go out.

• Size and swimming speed: These fish grow up to 3 inches in length. It’s a decent size for a seahorse tank mate. Like seahorses, Pajama Cardinals are also at a disadvantage when feeding.

They’re slow swimmers and can’t compete for food. They also have a peculiar swimming style. Instead of wiggling their bodies, they seem to float around while completely still.

• Space requirements: This is a sociable, shoaling species. You’ll need to adopt one small school or at least a pair. For that, you’ll need at least 30 gallons worth of aquarium space.
• Water parameters: They’re quite similar to seahorses in this regard. But they tolerate a narrow range of salinity levels. The ideal values include 72-79°F, 8.1-8.4 pH, 8-12 dGH, and 1.023-1.025 SG.

9. Striped Mandarinfish

Mandarinfish are among the most eye-catching specimens in the aquarium trade. There are a lot of color variations to choose from.

And besides their mesmerizing appearance, these fish are also excellent tank mates for community aquariums.

However, they’re not the most suitable for beginners. This fish has very specific dietary needs and needs to be kept in a live rock aquarium.

If you’re up for a challenge, here’s some more information on this species:

• Temperament and behavior: Striped Mandarinfish are pretty chill tank mates. They don’t go out of their way to interact with others in the tank.

They might completely ignore other species. Striped Mandarinfish prefer to spend most of their time by themselves, searching for food and floating lazily above the substrate.

Their shy nature shines through when they come into contact with other fish. When approached by others, the Mandarinfish might hide away even if its tank mates aren’t threatening.

• Size and swimming speed: They grow up to 3 inches long, but most fish are slightly smaller. They’re pretty slow swimmers, so don’t expect to see them darting around marathon-style.

They won’t compete with seahorses while feeding. They might accept foods like brine or mysis shrimp. But their favorite food is copepods. They might even eat that exclusively when kept in captivity.

• Space requirements: You’re going to need at least 30 gallons for one Mandarinfish. Luckily, this species doesn’t need to live in groups. You can keep them either alone, or as a pair.
• Water parameters: This fish requires 75-81°F temperature, 8.1-8.4 pH, and 8-12 dGH. The salinity should be 1.023-1.025.

10. Blue Leg Hermit Crab

Finally, we have the humble Hermit Crab. This is among the few crab species that I’d recommend in a seahorse tank.

Other larger crabs are quick and have a powerful pinch, so they represent a potential danger for seahorses.

But not the Blue Leg Hermit! This critter is a cheap, colorful, and very low-maintenance addition to a seahorse tank. And they have plenty of other perks:

• Temperament and behavior: This crab is super peaceful and can share a space with most species. The only exception is snails and other small crabs. The Blue Leg Hermit will attack these species to steal their shells.

Around seahorses and fish, they’re virtually inoffensive. They’ll spend most of their time ignoring other members in the tank.

Blue Leg Hermits spend most of their time in small groups, searching for food on the rocks and substrate. They’re also quite sedentary and mostly active at night.

• Size and swimming speed: This crab grows up to 1 inch. Despite their small size and voluminous shell, they can move pretty well.

They’re not fast, nor slow. But they crawl around without much difficulty. Sometimes, they might accidentally flip themselves over while trying to climb the rocks.

You can say they have average speed and are pretty clumsy. Even if they could move swiftly, they wouldn’t compete with seahorses for food. This crab eats mostly algae, detritus, and some species of bacteria growing on rocks.

• Space requirements: Luckily, hermit crabs don’t need a lot of space. They’re so small and sedentary, that 5 gallons per crab are more than enough. If you have 10 gallons to spare, you can easily fit 2-3 crabs in that.
• Water parameters: They’re a bit more adaptable than seahorses when it comes to water parameters. Blue Leg Hermit Crab can tolerate temperatures around 72-80°F and a pH between 8.0-8.5. They also thrive in a wider range of hardness and salinity. The water hardness can range between 8-16 dGH, and the SG can measure 1.018-1.025.

Conclusion

Seahorses are delicate, peaceful creatures. They’re also slow swimmers and have special dietary needs.

They must eat constantly to avoid starvation. They’re vulnerable to aggressive species. They also can’t compete with fast-swimming fish for food.

Apart from this, they also have specific water parameters. They can only tolerate alkaline and moderately hard water (8-12 dGH).

Despite being a tropical species, they also require slightly lower temperatures, around 72-76°F.

Considering all this, it might seem challenging to find the perfect mates for a community tank.

However, as you can see, this couldn’t be further from the truth! There are plenty of peaceful, slow-swimming species you can add to a seahorse aquarium.

You can choose between many colorful and interesting fish species, as well as snails and even hermit crabs!

All of the species I’ve listed in the article are perfectly compatible. But this is just the tip of the iceberg! If you have any other recommendations, feel free to write them in the comments!