Can You Keep Axolotls With Seahorses? Full Compatibility Guide.

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Seahorse keepers are always on the hunt looking for compatible new additions for their species-specific aquariums. One such bizarre option is axolotls, can these amphibians ke kept with seahorses? Let’s take a look.

Seahorses and axolotls can never be kept together. Seahorses are a type of marine fish requiring saltwater to thrive while axolotls are freshwater amphibians that aren’t able to tolerate the salinity of saltwater. Both creatures have a lot of physiological differences that make them unsuitable as tankmates. Keeping them together will result in extreme bodily pressure differences which soon leads to death.

Freshwater and saltwater fish are very different physiologically and cannot be put in waters that aren’t suitable for them.

Keeping axolotls in a seahorse tank will lead to their deterioration. Once the axolotl is introduced to saltwater their bodies will lose water through osmotic pressure.

Eventually, all the water the fish is made up of will exit their bodies leading to dehydration and death.

Even though axolotls can tolerate a certain level of salt, keeping them in a saltwater aquarium will be fatal.

Keeping seahorses in a freshwater tank is also just as dangerous 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 and eventually die.

By no means should you ever place fish under waters that aren’t suitable for them. Rather look for alternative ways of keeping your desired fish.


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.

Placing salt fish in freshwater will result in freshwater entering the fish’s body, causing the fish to swell hence death is the only option.


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 to stay healthy.

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

If freshwater fish are put in salt water, they will lose water from their bodies due to the hypertonic environment.

As a result, they will dehydrate, shrivel and die.

Alternative Ways Of Keeping Both.

Separate Tanks.

Even though seahorses and axolotls cant be kept together you can still fulfill your desire of keeping these two amazing creatures just that they would need to be in separate tanks.

You can set up two different aquariums one saltwater for the seahorse and one freshwater for the axolotls.

This is possibly the best and safest way of keeping these two creatures if you are adamant about keeping them.

Similar Inhabitants.

Alternatively, you can always choose other compatible similarly looking inhabitants to house your aquarium.

If you have a saltwater seahorse aquarium and looking to house an axolotl why not look for other suitable tankmates that are of similar resemblance to an axolotl?

The molly miller blenny is a good option for seahorses as they are seahorse compatible, saltwater fish that somewhat resemble axolotls in a way.

If you have an axolotl you can find other alternative tankmates that are compatible for them. Freshwater pipefish is a possible tankmate for seahorses.

They resemble seahorses but can live in freshwater, perfect additions to axolotl tanks.

Compatible Tankmates For Seahorses And Axolotls.

Tankmates For SeahorsesTankmates For Axolotls
1. Goby1. Dojo Loaches
2. Cardinal Fish2. Guppy Fish
3. Jawfish3. Zebra Danios
4. Gramma4. Cardinal Tetra
5. Scooter Blenny5. Endler’s Livebearers
6. Clownfish (caution)6. Rosy Barbs
7. Angelfish ( caution)7. Green Swordtails

Setting up A Seahorse Tank.

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 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. Make sure you choose a tank with the right size, shape, and dimension

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.

Make sure you choose a skimmer with a higher recommended usage for maximum filtration strength.

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.

These posts can be made of macroalgae, suitable coral, and other artificial objects. Be sure to make it firm and seahorse safe.

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.

If using live rock make sure the rock is free of hitchhikers and any other pests which can be introduced to your aquarium that might cause harm.

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

Normally a 2-inch sandbed is ideal for seahorse aquariums however be sure to choose the right texture and type for easy maintenance. If not this area can cause detritus to build up.

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.

Also, it’s imperative to place your seahorse aquarium away from direct sunlight to prevent a rise in water temperatures.

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

This process takes time, do not rush. Only introduce livestock once you’ve cycled the tank and tested the water making sure water quality is maintained.

9. Water parameters should be as follows.

  • Water temperature – Ideally 70-74F.
  • Specific gravity – 1.020-1.025.
  • pH – 8.1-8.4
  • Alkalinity – 8-12 Dkh
  • Ammonia (NH3) – 0
  • Nitrite (NO2) – 0
  • Nitrate (NO3) – <25PPM
  • Phosphate (PO4) – <0.2PPM
  • Calcium – 350-450PPM
  • Magnesium – 1250-1350PPM

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

Wild-caught is more fragile with a lower survival rate, it’s best to go for captive-bred specimens which have proven to be more domesticated and hardier.

11. 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.

Always keep an additional tank that you use to quarantine new arrivals.

12. 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.

Make sure you choose compatible crew members that won’t harm these ponies.

13. Proper daily, weekly, and monthly maintenance should be performed. This should involve daily temperature and water tests, weekly water changes and gravel siphoning, algae removals, and water top-ups.

Setting Up An Axolotl Tank.

1. Axolotls need an appropriate tank that’s big enough to house them. They don’t require much when it comes to tanks, with a minimum of 20 gallons with sufficient floor space being ideal.

However, it is recommended to have a 40-gallon tank since these creatures create a lot of waste, a bigger tank will help keep water paramaters stable.

2. Axolotl tanks don’t need substrate and many keepers choose to go bare bottom since it’s easier to maintain.

However, it’s best to provide a suitable sandbed to house these amphibians.

A bare-bottom tank although easier to maintain can cause them to stress due to the tank being slippery.

3. Axolotls give off a heavy bioload therefore a strong filtration system is required. But they also don’t do well with too much turbulence.

Therefore it’s better to use several powerheads on moderate instead of fewer powerheads on high. This will create the best possible outcome to prevent dead spots in the tank while keeping a moderate flow.

4. Axolotls require mental stimulation and enrichment. You must provide a fun yet safe aquascape for them to investigate and hide whenever they need to.

You can use rock, wood, or plants to form these cool features.

You also need to provide enough hiding spots. A hide is great for amphibians to seek refuge whenever they feel threatened.

5. Lighting isn’t a concern for axolotl tanks. These guys are nocturnal which means they are most active at night or when lighting is dim.

However, if you thinking of adding a few plants make sure you provide a subtle light that isn’t high-intensity.

Also, provide enough illuminated and shaded areas for your livestock to choose from according to their preference.

6. Water parameters should be as follows.

  • Water Temperature – Ideally 60-64 degrees Fahrenheit (16 – 18°C).
  • pH – 7.4 – 7.6
  • GH: 125-250ppm (7-14deg)
  • kH: 53-143ppm (3-8deg)
  • Ammonia (NH3): 0 ppm
  • Nitrite (NO2-): 0 ppm
  • Nitrate (NO3-): <60 ppm

7. Cycling is a long and important process of the initial stages of an aquarium. This helps increase the population of good bacteria needed to maintain a healthy tank.

Never introduce an axolotl to a tank that is new, always plan ahead and have the setup ready and cycled before you introduce livestock.

8. Maintenance will include water changes, gravel siphoning, and water conditioning if you using tap water.

Final Thoughts.

Seahorses and axolotls are both great aquatic creatures however they aren’t suitable as tankmates for obvious reasons.

However, you can still keep them just that they will be kept separately.

I hope this post served you well I trust you are on your way to some fun aquarium keeping. Enjoy the hobby, it’s rewarding.

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