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How to set up a dwarf seahorse tank – the guidelines!

Dwarf seahorses are the cutest!  As a breeder of the bigger species of seahorses, I love the idea of tiny, adorable little mini-ponies that stay small and always look so cute!  However, it’s taken me years to even consider trying to set up a tank of dwarfs.  They are more difficult to keep than the larger species and not the best seahorse for a beginner.  Many people are attracted to their less expensive upfront cost, but do not realize that the cost of keeping them well fed, and the maintenance required to keep their tank clean pretty much makes the amount of time, money and energy spent equal to that of larger species.

Because I have not had the pleasure of keeping these adorable mini-seahorses yet, I called on some of my expert friends to explain the most important considerations when setting up the tank. Thank you to Lucie Arawana, Tom Hornsby, and Dan @ Seahorse Source for answering so many questions!  You can watch the video version of this information by clicking here!

In this article, we’ll discuss a few of the successful ways to set up a dwarf seahorse tank, covering all the daily maintenance required to keep them healthy.  You should research dwarf seahorses in depth before taking on the challenge of raising them, but here are some of the basic facts ~

A dwarf seahorse tank is very similar to a fry tank, with the same needs and requirements.

DWARF SEAHORSES WILL DO BETTER IN SMALLER TANKS – 2-10 gallons is the recommended size
to keep this species, with 20-40 dwarfs per 5 gallons.  They prefer living in little communities, and just do better in groups.  You would not be able to see much of them in a huge tank, unless you kept a huge number of the little guys.  But, the main reason for the smaller tank is their feeding habits.  They do not chase food as much as the bigger seahorses, and will do better if the food is confined to a smaller space.  Providing enough live foods becomes much easier in a smaller space also.  However, a dwarf will reach adulthood in 3 short months, and start breeding.  Their gestation period (time the male carries the fry) is only 10-14 days, and they breed 3 generations per year.  So, the tank will not seem so small for long!


PROVIDING ADEQUATE FILTRATION IS IMPORTANT – Most will advise a bare-bottom set up with no
rock.  Hydroids and aptasia, which we will discuss in a moment, often come in to the tank as hitchhikers on rock and can kill the tiny dwarfs easily.  There are ways to treat rock for hitchhikers, but most find it easier to just use artificial hitches like fake plants.  The bare bottom set up makes cleaning much easier, but also makes keeping the tank cycled a more difficult task.  There are pros and cons to most methods, but the more sterile setting works best with delicate dwarfs.  This merely means that the biological bacteria will need somewhere else to live, and filtration and water changes become more important.

The following 4 methods have worked successfully for many dwarf keepers and breeders:

  • SUMP – An easy way to add more water volume and more room for biological filtration and equipment is to add a 20 gallon sump underneath. This is the best method, because you can use a better skimmer, have more “room for error” and cut off your biological media from the main tank by turning off the pump if you need to treat for hydroids or anything else.  The sump opens up multiple options that are not available in a HOB situation, like using K1, bricks, socks, reactors, UV sterilizers and many other types of media.

  • HOB WITH SPRAY BAR – Another successful way to provide filtration is to use an adjustable HOB (hang on back) filter with spray bar. The spray bar provides more flow to the tank, eliminating dead spots that allow waste to build up.  Dwarfs cannot handle much flow, but the adjustable function lets a keeper play with the settings until they work for the situation.  The internal filter or external canister attached to the spray bar can hold biological and mechanical filtration.
Click here to view internal filter
Ah, the beloved freeze frame always makes me look marvelous! If you click on the picture, you’ll be taken to this product though!
  • 2 TANK SWITCH – is exactly what it sounds like. Literally, keeping two identical tanks, and switching the seahorses to the cleaned tank every few days.  Cleaning involves bleaching and sterilizing the unused tank and all equipment.  This can work very well, but not many people will continue doing the switch indefinitely….and problems will start the moment they stop.  IMPORTANT NOTE:  if you chose to try this method, the dwarfs have been known to “play dead” when they are moved.  It can be quite scary (enough to consider a different method :)), so just be aware that this is one of their defense mechanisms.

  • SPONGE FILTER – Finally, a sponge filter set up can be an easy way to keep these adorable little guys and gals safely. The sponge will hold the good bacteria and keep the tank free of ammonia and nitrite.  An external air pump connects to the sponge via airline, and creates a suction effect that pulls waste towards the sponge, where it will stick until it is removed during a weekly cleaning.  Water movement and oxygenation occur as the bubbles coming from the filter hit the surface of the water.  During weekly water changes, swishing the sponge in old tank water to clean off the build up will help keep it working, and clean off all the built up waste.  But, never squeeze the sponge, as you’re only trying to remove the trapped waste….NOT the good bacteria living inside the sponge.
Click on the image to view sponge filters for sale
Click on the image to view sponge filters for sale

THE TANK NEEDS TO BE CLEANED DAILY– 15% weekly water changes need to be thorough.

click on the picture for great cleaning sponges!
Click to buy sponges!

No matter which filtration method you choose to use, the key to success is keeping the tank free of organic build up.  Have you ever touched the inside glass in your aquarium?  The amount of “sliminess” speaks volumes about the organic level in the tank.  In a natural set up, microfauna is a good thing.  But when the goal is to keep things ultra clean for dwarfs, all of the slime needs to go!  Therefore, in addition to the weekly water changes, daily siphoning of any waste or dead brine shrimp needs to include wiping every surface of the tank to keep any bad bacteria from growing.  Be sure to have a refractometer ready to determine how much RODI water, and how much replacement saltwater are needed in order to fill the tank back up, but still keep salinity the same.


DWARF SEAHORSES WILL NOT EAT FROZEN FOODS – I am still hoping that a breeder will successfully condition dwarfs to eat frozen foods, but even the few captive bred options on the market still require live feedings.  The instinct to only eat moving creatures is so ingrained in them, that they just never understand that a frozen crustacean is food.  So, a keeper must be able to keep an ongoing hatchery of live foods in order to keep the dwarfs fed.  Artemia (brine shrimp) is the easiest to culture and most often used to feed dwarf seahorses in captivity.  However, brine shrimp are not a natural food source, and do not contain the right type of nutrition that the dwarf seahorses require to stay healthy.  The key is enriching them.

Click for a link to Dan's feed
Click for a link to Dan’s feed

“Enriching” refers to feeding the artemia a blend of vitamins, microalgae and other food to make them healthier for the seahorses.  When you “gut-load” the crustacean with “goodies”, the seahorses will reap the benefits.  The important point is to learn as much as you can about brine shrimp, because keeping their “tanks” (or hatching and enriching containers) clean and well fed is as important as it is in the dwarf tank.  Culturing copepods is a great idea too, because they have more of the nutrition that the seahorses need, and a variety is always best.  However, The dwarfs can eat up to 3000 copepods a day, so it would be very difficult to use them as a main food source.  But providing both enriched brine shrimp and copepods gives the seahorses a cocktail of everything they need to stay strong.

The dwarfs need 2-4 daily “snowstorm” feedings.  Literally, this means putting enough live foods into the tank to make it look like a blizzard just hit.  Underfeeding is rarely an issue, but overfeeding can be determined by the “4 hour test”.  After 4 hours, the “blizzard” should have cleared and only a few flurries remain.  If the tank still resembles a storm after 4 hours, feed a little less the next time.  But, having live foods remain in the tank constantly is always a good thing, in case one little dwarf is still hungry!

HITCHHIKERS – The reason most people choose to keep dwarfs in an unnatural set up is to avoid hitchhikers.  Aptasia, hydroids, bristle worms and many other little critters that are just nuisance to the larger seahorses, will KILL a dwarf.  It’s important to note that even using fake plants with no substrate or rock, will not always prevent hydroids and other pests from finding their way into the aquarium.  One way they sneak in is on the brine shrimp cysts.  Using decapsulated brine shrimp will help, but keeping pancur / fenbendazole on hand is a very good idea.

HOW TO TREAT ROCK OR TANK FOR HYDROIDS – Fenbendazole  (panacur and safeguard are over-the-counter brands) is a goat wormer.  You’re probably wondering why I’ve taken such an odd turn, right?  Well, this wormer is also a hydroid killer.  YAY!  I typically frown upon chemicals in an aquarium, but when they save seahorses from hydroids….I will use them with a smile!  Using fenbendazole in a tank with coral is NOT advised.  In fact, if you treat rock for a dwarf system, it should not be used in a reef system later.  The rock can soak up the panacur and leech it back out later.  Some snails, bristle worms, and other cuc will also be affected.  So, make sure you plan to use the rock in only coral free tanks.

Click to buy fenbendazole
Click to buy fenbendazole

To treat a dwarf tank for hydroids, add 0.1 – 0.2 ml of panacur per 10 gallons every other day for 3 doses.  If you notice after the second day that the hydroids are not dying, raise the dose.  You can safely go 4 – 5 times the original dose, without any harm to the seahorses.

If you choose to treat rock before adding dwarf seahorses, using a stronger dose will be more effective.  So, 0.4 – 0.5 ml per 10 gallons should do the trick.  Just be sure there are no sensitive cuc members, macro or coral that might not handle the treatment well in the tank.

There are also nudibranchs that will eat hydroids, but they are very difficult to find, and don’t move very quickly.  In fact, if Todd Gardner (or anyone else) make them available to the hobby (come on Todd, hurry it up already!  ha), someone alert me immediately!

This is his “hurry up Todd” face! Click to pester Todd!

ANOTHER WAY – There are so many ways to do things, that writing this article was very difficult.  The main points to consider before buying dwarfs are:

  • Can you keep a small tank cycled and constantly clean?
  • Do you understand the nitrogen cycle and how to keep ammonia and nitrite at zero?
  • Do you have test kits to watch the parameters of your dwarf tank?
  • Can you provide live foods on a continuous regular basis?
  • Do you understand brine shrimp, how to keep a hatchery clean and know how to enrich live foods?
  • Do you have the tools to deal with hitchhikers?

Many people really want the natural tank look, and this can be achieved quite easily.  Using the basic fowler tank set up instructions (cycling the tank with rock and sand) can of course provide a pretty home to dwarfs.  Your risk tolerance level should determine a lot of your choices about set up, based on how much you are willing to risk and what your goal is in keeping the dwarfs.

If you want the natural set up, miracle mud capped with sand in a refugium can help the seahorses by providing trace minerals and all the benefits that a normal aquarium lacks.  These extra nutrients can strengthen the dwarfs and help them deal with any problems.  I’ve seen multiple very cool set ups with self-sustaining ecosystems using the miracle mud.  But they typically involve very large sumps, macroalgae and a long quarantine period.  A very good plan for an experienced keeper, but probably not a first time set up.  I’ll be posting miracle mud articles very soon, so stay tuned if you would like to learn more!

If you choose to try the natural method, the word to remember is  QUARANTINE!  EVERYTHING needs to be put through a process to eliminate pests.  Quarantine all rock, macroalgae and everything else for months before adding dwarfs.  A quarantine period of 3 months allows you to remove any hitchhikers manually, and most parasites will be eliminated without a fish host.   I am working on a detailed article and video showing how simple a quarantine tank and process can truly be….yet how many heartbreaks and problems it can help you avoid!  Taking precautions might take a little longer, but taking the time to do the natural set up correctly will result in a happy dwarf tank.

Once you have researched and decided what type of set up you are going to use and which filtration method will run the tank, the final step is just having the patience to take your time and do things right.  To list the actual steps:

  1.  Choose a 2-10 gallon tank
  2. Determine which filtration method to use and plumb the sump if possible
  3. Cycle the tank, unless using the 2 tank swap method (A lot of people recommend media from an established tank, but please don’t take any from a tank that might add all of the hitchhikers that you are trying to avoid.  Media from a reef tank might have good bacteria ready, but it might also have a lot of things you do not want).
  4. TEST THE TANK.  I like the ammonia test, but just be certain the tank can handle the constant feeding and pooping of multiple seahorses and their foods using test kits versus guessing.
  5. Set up the live food cultures/hatcheries and get used to keeping and cleaning them
  6. Stock up on proper enrichment supplies for the live feeds
  7. Quarantine any rock, macro, or other live thing going into the tank to prevent pests and parasites.
  8. Treat rock tanks with fenbendazole
  9. Cover any intakes and add live feeds to play with the flow rate (this is to make sure the circulation is not so strong that the live foods are sucked up the filter or down to the sump, but is strong enough to prevent dead spots)
  10. Buy the dwarf seahorses (if you buy from an unknown source, a freshwater dip followed by quarantine can help rid the seahorse of unwanted pathogens and also help you determine whether further treatment is needed – more info on this coming soon!)
  11. DOUBLE CHECK EVERYTHING like temp, salinity, ph and ammonia/nitrite before adding the seahorses
  12. Temperature acclimate the seahorses to your tank, and adjust flow based on reaction
  13. Enjoy your magical mini-seahorse aquarium!


These miniature seahorses do require more work than the bigger species, but their iridescent coloring and adorable interactions make them hard for a hobbyist to resist!  I will be setting up my dwarf tank soon, and sharing the step by step process via video.  I would love to see any of your dwarf seahorse tanks and what has worked for you!