Re:set up dwarf seahorse tank

Pete Giwojna

Dear KC:

Good old Instant Ocean artificial salt mix will work just fine for your dwarf seahorses. If you want to fill up a 3 gallon aquarium, just buy a 10 gallon package of the Instant Ocean from your local fish store and add up all 1/3 of the salt mix to the aquarium water. That should produce a specific gravity that’s fairly close to what is desired. You can then adjust the salinity of the specific gravity as needed by adding a little freshwater to lower the salinity or adding a bit more of the artificial salt mix to raise the salinity slightly.

Strive to maintain stable water conditions within the following water quality parameters when you set up your dwarf seahorse tank:

Temperature = range 68°F to 80°F (20°C-27°C), optimum 75°F (24°C).
Specific Gravity = range 1.018 – 1.024, optimum 1.019-1.022
pH = 8.0 – 8.4, optimum ~8.2
Ammonia = 0
Nitrite = 0
Nitrate = range 0-20 ppm, optimum 0-10 ppm
Suggested Stocking Density: 2 pairs per 1 gallon (4 liters).

The only filtration you’ll need on a small aquarium suitable for dwarf seahorses (Hippocampus zosterae) is an air-operated sponge filter or an air-operated undergravel filter, KC. However, the sure to avoid sponge filters with weighted bottoms or other metal components since they will rust when exposed to saltwater. Sooner or later this will cause problems in a marine aquarium (sooner in the small setups that are most suitable for H. zosterae). Select a sponge filter that has no metal parts and is safe for use in saltwater. The proper units will have suction cups to anchor them in place rather than a weighted bottom.

The sponge filters I find that work well are the Oxygen Plus Bio-Filters (models 2, 3, 4, or 5) or the Tetra Brilliant foam filters. They have no metal components, making them completely safe for use in saltwater, and just one of these foam filters will do the job on a tank of 5 gallons or less. They do not have a weighted bottom but are equipped with suction cups instead.

Click here: Foam Aquarium Filters: Oxygen Plus Bio-Filter 2

Avoid the Oxygen Plus Bio-filter 6, 11, and the Multi sponge, which all have a weighted bottom (metal), that rusts when exposed to saltwater. If you want more filtration, you’re better off going with two of the smaller suction cup sponge filters rather than any of the models with weighted bottoms. For instance, for a 12 -gallon tank, I’d suggest using two well-established foam filters, one at either end of the tank for the biofiltration, just as you are planning, Alex.

All you need to operate sponge or foam filters is an inexpensive, diaphragm-operated air pump (whatever is available at a reasonable price from your LFS will do just fine), a length of airline tubing to connect the air pump to the foam filter(s), and a set of air valves (gang valves) to regulate the air flow to the filters. That’s all — nothing to it! The inexpensive Apollo 5 air pumps work great for sponge filters, but whatever air pump you have on hand should certainly do the job.

Cleaning the foam filters is a snap. Simply immerse them in a bucket of saltwater and gently squeeze out the sponge until it’s clean and releases no more sediment or debris. (I use the saltwater I siphoned out of my aquarium when performing a water change for this, and clean my sponge filters whenever I change water.) Run a bottlebrush through the inside of the tube, wipe off the outside of the tube, and you’re done. The filter is ready to go back in the aquarium with no impairment at all of the biofiltration. Takes only a couple minutes.

I like to keep a few extra sponge filters running in my sump or a refugium at all times. That way, I’ve got instant, fully established, portable biofilters I can use wherever needed — a hospital ward or quarantine tank, a nursery tank or rearing tank, a brand new setup, or anytime the biofiltration needs a boost in another tank for any reason. Very versatile! You’ll never realize how valuable an instant biofilter can be until you really need one.

If you don’t have them already, you will need some saltwater test kits to cycle your tank, monitor conditions in your aquarium, and keep track of the water quality. The basic test kits you’ll need to keep track of the aquarium parameters are pH, ammonia, nitrite, and nitrate, plus a hydrometer to check specific gravity and an aquarium thermometer (if you don’t have one already). You’ll need to get separate test kits for ammonia, nitrite, and nitrate, and I recommend fasTest or Salifert kits for saltwater. I also like the SeaTest hydrometers–convenient, easy to read, and reliable. Here’s a list of what you’ll need for starters:

Small aquarium (no more than 10 gallons)
Cover for aquarium
Strip Reflector with bulb (a fluorescent bulbs is better than an incandescent bulb since it will give off less heat)
A set of the following Instant Ocean® Test Kits by Aquarium Pharmaceuticals:
Ammonia test kit for saltwater;
Nitrite test kit for saltwater;
Nitrate test kit for saltwater;
pH test kit for saltwater;
or the Salifert Nitrogen Cycle Package of test kits (Ammonia, Nitrite, Nitrate, & pH)
Click here: Salifert Test Kits:
Instant Ocean artificial salt mix
Safe or Prime declorinators by Sea Chem for detoxifying tap water;
SeaTest Hydrometer (by Aquarium Systems) for checking salinity;
Aquarium thermometer.
Brine shrimp eggs (Artemia cysts)
Brine shrimp net
Brine shrimp hatcheries (at least two)
2 air pumps (one to operate the sponge filter or undergravel filter in the tank and one to aerate the brine shrimp hatcheries)
Airline tubing
Set of Gang Valves (to connect the airline tubing from your air pump to the brine shrimp hatcheries)
Macroalgae (to provide a lush letter of plants for the dwarf seahorses to live in)
Sponge Filters (one or two depending on the size of the aquarium)
A copy of the Complete Guide to Dwarf Seahorses in the Aquarium by Alissa Wagner Abbott

The prices for these items vary considerably depending on what part of the country you are in, as well as from source to source. The items can often be found for bargain prices online, but then you have to pay for shipping and handling, which adds to their cost. For this reason, it’s usually best to get the large equipment at least (the aquarium, cover, reflector, etc.) from your local fish store. I suggest you print out this list of items and then compare prices at fish stores in your area as well as various online sources to determine where you can get the best deals.

Once you have all the equipment for your new dwarf seahorse tank setup, KC, you will need to cycle the aquarium and establish the biofiltration before it will be able to support seahorses or any other life. Here are some instructions on how to proceed when you’re ready to cycle the aquarium and establish the beneficial nitrifying bacteria in your sponge filter(s):

Cycling the Aquarium

Until it has cycled, your aquarium will be unable to support life. Cycling simply means to build up a healthy population of beneficial bacteria in your tank that can carry out the nitrogen cycle and breakdown your fishes’ waste products.

Ammonia (NH3), nitrite (NO2), and nitrate (NO3) are all nitrogenous (nitrogen containing) wastes. All living aquarium animals whether they be fish or invertebrates excrete these wastes, and they are also produced by the decay of protein-containing organic matter (uneaten food, detritus, dead fish or inverts, etc.). The nitrogen cycle breaks down these wastes in a series of steps into nitrogen gas (N2) which leaves the aquarium as bubbles.

The nitrogen cycle begins with ammonia, which is highly poisonous. In the first step of the cycle, Nitrosomonas bacteria reduce ammonia to nitrite, which is also very toxic. In the second step of the nitrogen cycle, Nitrobacter bacteria convert the nitrite to nitrate, which is relatively harmless but becomes harmful when it accumulates in high enough levels. In the third and final step of the cycle, denitrifying bacteria then convert the nitrate into completely harmless N2, which of course bubbles out of the tank as nitrogen gas. In this way, thanks to the nitrogen cycle, dangerous wastes are converted into progressively less harmful compounds and finally removed from the aquarium altogether.

When we set up a new aquarium, and wait for it to cycle, we are simply allowing a big enough population of these different types of bacteria to build up in the biofilter to break down all of the wastes that will be produced when the aquarium is stocked. If we don’t wait long enough for the cycle to complete itself and the biofiltration to become fully established, and hastily add too many specimens to a new aquarium too soon, they will die from ammonia poisoning or nitrite toxicity. This is such a common mistake among us impatient aquarists, that when fish get sick and/or die from ammonia/ntrite poisoning, it is commonly called the "new tank syndrome."

When your aquarium has completely cycled, the ammonia levels will stay at zero because, now that your biofilter is fully established, there is a large enough population of aerobic (oxygen loving) nitrifying Nitrosomonas bacteria to reduce all of the ammonia to nitrite as fast as the ammonia is being produced. The nitrite levels will likewise stay at zero because there is also a large enough population of aerobic (oxygen loving) nitrifying Nitrobacter bacteria to convert all of the nitrite to nitrate as fast as the nitrite is being produced.

The nitrate levels ordinarily continue to build up, however, because there are simply not enough anaerobic (oxygen hating) denitrifying bacteria to convert all of the nitrate that’s being produced into nitrogen gas (N2). Since nitrates are being produced faster than they can be transformed to nitrogen gas, the excess nitrates accumulate steadily in your aquarium. That’s perfectly normal, since the denitrifying bacteria that carry out that final step, the conversion of nitrate (NO3) to nitrogen (N2), are anaerobes that can only exist in the absence of oxygen. For our aquariums to support life, and for the fish and invertebrates to breathe and survive, our tanks must be well aerated and well circulated so that there’s plenty of dissolved oxygen in the water at all times. That means there are normally very few areas in our aquariums where anaerobic denitrifying bacteria can survive, limiting their population accordingly (which is generally good, since some anaerobes produce deadly hydrogen sulfide gas during the decay of organic matter and would poison our tanks if allowed to proliferate).

Consequently, most aquariums lack a sufficient population of anaerobic denitrifying bacteria to complete the nitrogen cycle and convert nitrate to nitrogen as fast as the nitrates are being produced. The only way to keep the nitrates from building up to harmful levels in such setups is with regular water changes and by harvesting Caulerpa or other macroalgae periodically after it has utilized nitrates for growth. Overcrowding, overfeeding, or under filtration exacerbate the problem by resulting in more nitrates being produced and more frequent water changes being required to control the nitrate levels. You will keep nitrates at harmless levels by performing regular water changes, harvesting Caulerpa macroalgae periodically, and good aquarium management.

Prepare your aquarium for cycling by setting your system up with just freshwater at first, attaching the equipment and apparatus (sponge filter, aeration, circulation, lighting, accessories) and testing it all for a day or so to make sure you have everything in place, and that it works. Once assured that everything’s operating properly and there are no leaks, go ahead and add the substrate, salt mix, and aquarium décor, and leave everything running for a good week, allowing the various components and water to "settle in" before adding your microbes and "seeding" the tank with beneficial bacteria that will eventually establish your biofilter.

If you are using live rock, it contains all the bacteria needed to seed the tank, so all you have to do is position the live rock in attractive arrangements, provide a source of ammonia to feed the beneficial bacteria, and wait for the population of nitrifying and denitrifying bacteria to build up and stabilize.

If you are not using live rock (this means you, KC!), there are a number of different ways to seed the tank with bacteria and feed it with ammonia so cycling can proceed. Two popular methods are the fishless cycle, which I recommend, and the use of hardy, inexpensive (i.e., expendable) fish to produce ammonia and cycle the aquarium. Often used for this method are marine damselfish or mollies, which can easily be converted to saltwater. Both are very hardy and generally survive the cycling process, but I find this method to be needlessly hard on the fish and exposing them to the toxic ammonia and nitrite produced during cycling certainly causes them stress. Damselfish are far too aggressive and territorial to leave in the aquarium afterwards as tankmates for seahorses. Mollies are a possibility, but they really look out of place in a saltwater setup.

So all things considered, I suggest you try cycling your tank without fish. It’s really very easy. To use the fishless cycle, you need to add something else that will increase the ammonia level so the nitrifying bacteria can build up. I like to use a piece of cocktail shrimp (regular uncooked eating shrimp from the grocery store) and leave this in the tank to decay during the whole cycle. The decaying shrimp produces plenty of ammonia to kick-start the cycling process. This method should work great for cycling your dwarfs seahorse tank, KC.

After about 3 days after you add the shrimp, you will notice a spike in ammonia levels until the Nitrosomonas bacteria build up enough to break down the ammonia. When that happens, you will notice the ammonia levels rapidly dropping. (If for some reason your ammonia does not hit the top of the charts initially, you may want to add another piece of shrimp.)

The byproduct of ammonia is nitrite, and during this stage of the cycling process, as the ammonia falls, you will have a corresponding increase in nitrites until the population of Nitrobacter bacteria builds up. Nitrite levels will then fall as the Nitrobacter convert the nitrite to nitrate.

It is important to use your test kits every day or two when cycling your tank to monitor the progress of the process. As described above, at first you will see a rapid rise in ammonia levels with no detectable nitrite or nitrate. Then, as Nitrosomonas bacteria begin converting ammonia to nitrite, the ammonia levels will fall and nitrite readings will steadily rise. Nitrite levels will peak as the ammonia drops to zero. Next, Nitrobacter will begin converting the nitrite to nitrate, and your nitrite readings will fall as the level of nitrate rises. Finally, after the nitrites also read zero, you are ready to stock your tank. At this point, your ammonia and nitrite levels should both be zero, nitrates will be building up, and algae will usually begin to grow. This will tell you that your biofilter is active and functioning properly, and that you can now safely begin stocking the tank. It generally takes about 4-6 weeks to cycle a tank this way from scratch.

Once the tank has cycled, you can introduce a lush bed of macroalgae and your cleanup crew and then order your seahorses.

The only drawback to setting up the miniature tank for Pixies or dwarf seahorses is the eating habits of these miniature marvels, KC. Because of their small size and sedentary lifestyle, dwarf seahorses cannot be consistently trained to eat frozen foods without risking polluting the aquarium with uneaten food. As a result, the adults must be provided with copious amounts of newly-hatched brine shrimp (Artemia nauplii) at least twice a day and the fry must have access to bbs throughout the day.

This means maintaining a battery of brine shrimp hatcheries and hatching out large quantities of brine shrimp on a daily basis. If you are not proficient at hatching out brine shrimp or consider that to be too much of a hassle, then dwarf seahorses are not for you!

Here are some guidelines and instructions on hatching the brine shrimp you need to feed dwarf seahorses or Pixies so you’ll have a better idea what that requires:

Hatching Brine Shrimp

Brine shrimp are hatched in saltwater, not freshwater. Be sure to set up an array of at least two brine shrimp hatcheries so you can hatch out more baby brine shrimp each day before you run out. Many commercially made hatcheries are available or you can easily improvise your own from 2-liter soda pop bottles or quart jars. Fill the jars or bottles about 4/5 full with saltwater and equip each container with an airstone connected to a length of rigid airline tubing that reaches all the way to the bottom. An inexpensive vibrator air pump with a set of gang valves with put out enough air for the entire battery of hatching containers. Add 1/8-1/4 teaspoon of brine shrimp eggs to each container and adjust the valves so the airstones bubble vigorously, keeping the eggs in suspension at all times. Shine a light directly on the hatching bottles and keep them illuminated 24 hours a day.

The eggs will begin hatching after 18-24 hours, and the emerging nauplii should be harvested and used as soon as possible after incubation while they still retain their full nutritional value. (The yolk supply lasts about 1-2 days after hatching, and the food value of the nauplii deteriorates steadily as the yolk sac is consumed. Once it has been exhausted after about 48 hours, the nutritional worth of the nauplii drops drastically.)

However, before they can be used as food, the nauplii must first be separated from the indigestible egg shells. Otherwise the empty shells may be accidentally ingested by the seahorses, which has been known to cause intestinal blockages and death.

The brine shrimp nauplii can be separated from the eggs simply by turning off the air for a few minutes and allowing the water to settle. The unhatched eggs will sink to the bottom of the hatching jar while the empty egg shells will float to the top. The nauplii can then be concentrated in the center of the jar by darkening the room and shining a flashlight on the jar’s midsection. (Brine shrimp are attracted to light and will be drawn together in midwater where the light is focused.) Harvest the nauplii by using a siphon or turkey baster to suck up the concentrated mass of shrimp. The shrimp-laden water can then be strained through a plankton screen or fine-meshed brine shrimp net.

Return the strained water to the hatching container, add more eggs, and readjust the aeration. The same hatching solution can be used for a week’s worth of hatchings before it has to be replaced.

Alternating the hatching container from which you harvest each day’s supply of nauplii will assure that you have a nonstop supply of newly hatched brine shrimp available at all times. For best results, you should decapsulate the cysts before hatching them, as explained below.

If you’re still uncertain about how to proceed, KC, the information at the following link should make everything perfectly clear:

Click here: Brine Shrimp Technical Information 1

Be sure sure to pick up a copy of Alisa Abbott’s guidebook (Complete Guide to Dwarf Seahorses in the Aquarium, 2003, 144 pages), too, KC. That’s one book every Pixie owner and dwarf seahorse keeper should have on hand. I proofed Alisa’s dwarf seahorse book for TFH publications and wrote the preface for it, so I’m quite familiar with her guide, and I highly recommend it.

Best of luck with your new dwarf seahorse setup, KC!

Happy trails!
Pete Giwojna

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