Can Seahorses Be Kept With Goldfish? Full Compatibility Guide.

This post may contain affiliate links. If you click an affiliate link and make a purchase, I may earn a commission.

Seahorses are becoming more and more popular and with the arrival of the new captive-bred species it’s now easier than ever to get your hands on them. Maintaining them is also easier since these domesticated breeds are a lot hardier and more resistant.

However finding the right tankmates for them can be challenging, one possible tankmate is a goldfish! Can this be a good pairing match? let’s take a look.

Seahorses cannot be kept with goldfish since seahorses are marine fish and require salt water to survive, while goldfish are freshwater fish requiring fresh water to survive. Keeping them together is harmful and can lead to instant death. They should never be put together at all costs.

Freshwater and saltwater fish may be the same in terms of anatomy but they are very different physiologically and cannot be put in waters that aren’t suitable for them.

Keeping goldfish in a seahorse tank will lead to their deterioration. Once the goldfish fish is placed in saltwater their bodies will lose water through a process called osmosis.

Eventually, all the water in the fish’s body will exit leading to dehydration and rapid death.

Likewise, when keeping seahorses in a freshwater tank it’s just as fatal since these marine fish contain high concentrations of salt solution.

Placing them in freshwater, the water will flow through their bodies causing them to swell or even rupture and eventually die.

By no means should you ever place fish under waters that aren’t suitable for them.

Rather keep your desired fish in a separate tank set up with the right conditions needed for them to thrive.



Both seahorses and goldfish are extremely aesthetic and unique making them great tank occupants in just about any aquarium.

Unfortunately, you can’t keep them together, however, you can keep them separately.

This will involve having two tanks, a freshwater, and a saltwater tank which caters to their individual needs.

In this way, you get to keep both fish just that it will be kept separately.


If you are not interested in having two separate tanks rather look for other tank occupants that are similar to what you looking for.

For example, if you want to keep seahorses with goldfish, you can opt for pipe fish instead of seahorses.

Pipefish are similar to seahorses and most importantly is that they come in freshwater species that you can keep with goldfish (if compatible).

Alternatively, if you already have seahorses and you want to keep goldfish, you can look for other replacements that are similar to goldfish but are marine fish.

These include fish like angelfish, goby, and flame hawkfish. All these fish are similar to goldfish but are actually saltwater species.


Saltwater fish are marine life that comes from the ocean. These fish are just like freshwater fish in their anatomy but their physiological difference is significant.

These differences are found in how they regulate water and salts in their internal cells, also known as osmoregulation.

Water naturally seeks a chemical balance or equilibrium.

That means water flows from areas of higher concentration to areas of lower water concentration to equalize the system.

Saltwater fish will therefore lose water through their gills and skin.

Because the fish is losing water, it must drink a lot to stay hydrated but salty seawater is the only water around.

To get rid of excess salt, the fish’s kidneys pump lots of salt into its urine.

This is how saltwater fish function and are adapted to their environment in aids to conserve water.


Freshwater fish are fish that lives in freshwater such as lakes, rivers, and streams. These fish function a little differently.

Freshwater fishes are adapted to conserve salt because there isn’t as much of it in their environment.

It takes water in through its skin and gills all the time in order to stay healthy.

As a result, it produces much more urine than saltwater fish.


Setting up a seahorse tank is essential for their well-being since the wrong set-up often by beginners leads to seahorse death.

These are some of the essential rules to follow when setting up a seahorse tank.

1. Seahorses need the right tank that’s catered to their specific needs. They require at least a 30-gallon tank with enough vertical and horizontal space to cater to their upright swimming posture.

Enough space is also required for them to perform their daily courting rituals.

2. They need a solid filtration system to cater to their messy tendencies. This should include mechanical, chemical, and biological filtration.

3. The use of a protein skimmer is recommended even though it’s not a need, it will save you a lot in terms of maintenance.

4. Hitching posts are also needed for seahorses since they are weak swimmers they use their prehensile tails to wrap around objects keeping them anchored.

5. Rock and artificial aquascapes can be made to suit their requirements. This will ultimately assist in providing hiding spaces for them to seek refuge when they feel threatened.

6. Seahorses don’t really need substrate but depending on other tankmates you may need to provide a suitable sandbed.

7. Seahorses don’t have any lighting preferences, an ordinary day/night light with smooth dusk and dawn transitions would be ideal.

Preferably a bluish/white light has been used to bring out the brightest colors in seahorses.

8. Seahorses need mature water that has been cycled. It requires enough beneficial bacteria to help keep ammonia and nitrite levels down.

9. Stocking up on seahorses is also important since captive-bred seahorses are recommended rather than wild-caught.

10. Proper quarantine and acclimation is of utmost importance since you don’t want to introduce any diseases and pests into your system.

Acclimation should be performed as per the breeder’s instructions for the best possible transitions.

11. Clean-up crews are essential when keeping seahorses since they consume leftovers before they can break down releasing harmful substances which are toxic for tank inhabitants.


Goldfish will need a freshwater tank with the right setup for them to thrive. The following steps are just a guide to help set up their tank.

1. Goldfish need a good spacious living environment to thrive, they require at least a 10-gallon tank for a single standard fish.

Larger goldfish species need a bigger tank, also if you intend on keeping more than one goldfish larger space is required.

2. Proper filtration is required to keep your tank clean and reduce the amount of harmful bacteria which can lead to disease.

You can choose either external or internal filters, both are ideal for goldfish and will do a good job keeping the water clean.

3. A Heater/cooler is also needed to keep temperatures ideal for them to remain comfortable.

Normally goldfish require a temperature of around  68-74˚F (20-23.3˚C). Having a heater/cooler can help keep the water temperature within safe parameters.

4. A substrate bottom is not needed but its recommended since the substrate provides enough surface area for beneficial bacteria to grow.

Also remember to choose the right textured substrate since finer substrate can be ingested by the fish, rather opt for gravel of larger sizes

5. Aquascapes are great for adding hiding places for them to investigate and seek refuge in. You can put together your own aquascape by using rock, plants, and artificial structures.

Make sure the stuff you are adding to your tank won’t affect the chemical balance of the water.

6. Lighting is also required for day/night routines. LED lighting works well since you get great control and customization.

7. Conditioned water is ideal for goldfish, do not use any other water since it can be detrimental to their well-being. If you use tap water make sure you add a conditioner that will neutralize chlorine.

8. Cycling is another important process since it helps build beneficial bacteria. This process can take up to a month for a healthy population of bacteria to form.

9. Once the cycling process is complete and the water is tested and safe you can go ahead and introduce goldfish to your newly setup system.

Make sure you get healthy goldfish free from diseases and pests. Adequate quarantining and acclimation are required as per breeders’ regulations.

10. You can also choose to add other tankmates provided they are compatible with goldfish.

11. Thereafter proper maintenance and feeding are required.


Tankmates For SeahorsesTankmates For Goldfish
1. Goby1. White Cloud Mountain Minnows
2. Cardinal Fish2. Ricefish
3. Jawfish3. Variatus Platy
4. Gramma4. Longfin Rosy Barbs
5. Scooter Blenny5. Giant Danio
6. Clownfish (caution)6. Swordtail
7. Tangs ( caution)7. Rasbora Heteromorpha

Final Thoughts.

Goldfish and seahorses can never be kept together in the same tank. These two are both different fish with different requirements.

Goldfish are freshwater and seahorses are saltwater fish, you should never try to pair them.

Rather choose to keep both in separate tanks or find other alternative species that are similar.

Leave a Reply

Your email address will not be published. Required fields are marked *