Seahorse Tanks

Dear Monica:

Yes, the pair of snow flake clownfish that you obtained from ORA should be compatible with Ocean Rider Sunbursts (Hippocampus erectus) and red banded pipefish (Doryrhamphus dactyliophorus), Monica. As I understand it, the snow flake clownfish are simply a different color morph of the standard ORA Amphiprion occelaris and/or Amphiprion percula clownfish, and they are the two species of clowns that are best suited as companions for seahorses. Like the other ORA strains of clownfish, the pretty snow flake clowns with their fancy markings are captive-bred-and-raised clownfish, which are the best choice if you want to keep clowns with seahorses.

So I do think that the Sunbursts and the pipefish would do well with your pair of pretty snow flake clownfish, Monica. The one problem that sometimes crops up when keeping Ocean Rider seahorses with Amphiprion occelaris or percula clownfish, such as your snow flake clowns, is competition for food. The clownfish are fond of the frozen Mysis that is the staple food for the seahorses, and the clowns are equally fond of the copepods, baby brine shrimp, Nutramar ova, and other favorite foods of the pipefish, and because the clownfish are more aggressive feeders that the seahorses and pipefish, that can sometimes Keep things at feeding time.

However, any such problems are usually very easy to overcome simply by target feeding the seahorses and pipefish to make sure that they get their fair share at mealtime, or by training them to eat their frozen Mysis from a feeding station, Monica. Both target feeding and setting up a feeding station are very easy to accomplish and allow the Sunbursts and other seahorses to be kept in a community situation with other fishes that might otherwise out-compete them for food, such as your prized pair of snowflake clownfish.

The recommended stocking density for Ocean Rider Mustangs or Sunbursts (Hippocampus erectus) is one pair per 10 gallons, with a minimum tank size of 30 gallons, Monica. So a 38-gallon aquarium with an efficient filtration system could safely support up to 3-4 pairs of large tropical seahorses such as Mustangs or Sunbursts, or up to 7-8 adult individuals, when it was fully stocked.

But, of course, it’s always best to keep your aquarium under stocked rather than stocking it to capacity in order to provide a reasonable margin for error and make it easier to maintain optimal water at all times. This is especially important if you are new to seahorse keeping and the Sunbursts would be your first seahorses, Monica. Under those circumstances, it would be best to limit yourself to one or two pairs of the Sunbursts, plus the red banded pipefish, together with your pair of snowflake clownfish. Your 38-gallon aquarium system should be able to safely support all of those specimens and still allow you a reasonably comfortable margin for error.

On the other hand,, I also feel that your 20-gallon aquarium system would be overstocked if you were to keep all of the specimens you mentioned together in the smaller tank, Monica. A pair of blue stripe pipefish, plus a pair of Sunbursts seahorses, plus a pair of red banded pipefish, plus a pair of fancy snowflake clownfish would be overloading your 20-gallon tank, I believe, espec ially when you consider that the tank will also be housing mushroom corals and the cleanup crew.

For one thing, the 20-gallon aquarium is a little on the small side to begin with for both the Sunbursts and the red banded pipefish, which are larger than the blue stripe pipefish you currently have, Monica. Secondly, you must also consider the fact that the seahorses and pipefish are messy eaters, which means that the aquarium system must also be able to deal with the increased nutrient loading resulting from the seahorses’ and pipefishes’ leftovers.

If your 20-gallon aquarium included a very efficient filtration system that could maintain optimal water quality at all times despite the messy feeding habits of the pipefish and the ponies and the fact that it was stocked to capacity, then you might be able to pull off keeping all of the specimens gather in the smaller tank, Monica. But your 20 gallon aquarium system is not equipped with a sump or a protein skimmer and relies only on external power filters instead, which makes me think that maintaining optimal water quality would quickly become increasingly unlikely. (I do like the fact that you have included Chemi-Pure in the filtration system for both tanks, Monica. The Chemi-Pure is an excellent chemical filtration medium and is a good choice for a seahorse tank, but the Chemi-Pure alone will not in itself be able to overcome the other shortcomings of the smaller 20-gallon aquarium system.)

I know that you have included the Penguin Biowheel 200 together with the TopFin 10 on the 20-gallon tank, doubling up on external power filters in essence, in order to improve the filtration ability on your smaller aquarium, Monica, but the problem with that is that having both filters running at the same time is going to be too much for a tank of that size, just as you surmised. For example, the Penguin biowheel 200 is itself rated for aquariums of up to 50 gallon and it has an output of 200 gallons per hour. That means it will turn over the entire water volume of the 20-gallon aquarium 10 times every hour, which is a little too much of a good thing for the seahorses. (You need a turnover rate of at least five times per gallon for seahorses, with a turnover rate of 7-8 being ideal, and anything more than that can be problematic for the ponies. Turnover rates approaching 10 times per hour or more can overwhelm the seahorses, so when you add the output of the TopFin 10 to the 200 gallon per hour Penguin Biowheel, all of a sudden you’ve created too much water movement for the tiny tank for the seahorses to be comfortable.) We’ll discuss the water circulation for a seahorse setup in more detail below, but you would definitely need to tone things down in your 20-gallon aquarium just to make sure that the water currents were suitable for the seahorses.

For these reasons, I would favor the 38-gallon Innovative Marine Mini Nuvo aquarium system for the Sunbursts and pipefish instead of the smaller 20 gallon tank, Monica. In addition to the larger water volume, the 38-gallon Mini Nuvo aquarium also has a more efficient filtration system including phosphate sponges and a built-in compartment for a protein skimmer, which you can easily add.

However, the standard water pump that comes with the 38-gallon Innovative Marine Mini Nuvo Aquarium system has an output of 476 gph, which would turn over the entire water volume a bit over 12.5 times per hour (476 gph/38 g = 12.5 times per hour). Unfortunately, a turnover rate of 12.5 times per hour would produce powerful water currents that are too overwhelming for the seahorses, so right now you have the same problem of too much water flow a 38-gallon aquarium system as well.

Seahorses do best with a turnover rate of at least five times per hour, and I prefer for the water pumps and filters in my seahorse tanks to turn over the entire water volume of the aquarium about seven times per hour for best results. So in order to use your 38-gallon Innovative Marine Mini Nuvo aquarium system for seahorses, Monica, you would need to adjust the turnover rate to about half of what it is right now.

This could be accomplished couple of different ways. First of all, you could replace the water pump that comes with the 30-gallon aquarium system with a smaller water that puts out a little more than half as much as the 476 gph water pump. Or, you could install a spray bar return which would soften and diffuse the output from the powerful 476 gallons per hour water pump enough so that the resulting water flow was suitable for the seahorses.

This is normally what I advise home hobbyists regarding the water flow in their seahorse setups, Monica:

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Water Circulation for the Seahorse tank

Many seahorse keepers are overly conscious of the inactive life style and limited swimming ability of Hippocampus, and have adjusted their flow rates accordingly, resulting in undercirculated tanks with too little water movement. That’s a serious mistake for a small, close-system aquarium.

In actuality, seahorses prefer moderate water movement, including some areas of brisk current, providing there are also sheltered spots and some areas of relatively slack water they can move to when desired. Slack water means comparatively low flow, NOT stagnant conditions! As with any aquarium, avoid dead spots and stagnant areas in the seahorse tank at all costs (Giwojna, unpublished text).

Contrary to popular opinion, seahorses are quite effective swimmers that can hold their own in strong currents as long as sheltered areas are available (Delbeek, Oct. 2001). I have often discussed this matter with professional divers and collectors who regularly encounter seahorses in the ocean, and they report that the horses are often found where you would least expect them — well offshore and thriving in areas with powerful currents. For example, here is how Paul Baldassano, a commercial diver in New York who makes his living collecting sea urchins, describes the behavior of his local seahorses:

"In regard to seahorses in the wild, I occasionally see Hippocampus erectus in the wild while SCUBA diving but never in the places where they are supposed to be. I see them in the open sea far from shore and also in areas with large rocks and very strong currents. The last one I saw was in a channel off the south shore of Long Island New York in water about 12 feet deep. The current was so strong that I had to hold on to the rocks so as not to be swept away. This Hippocampus erectus was having no trouble staying there munching on the abundant plankton. Apparently they find places near the rocks where there is no current because as you know they are lousy swimmers. There is also a large population of seahorses in a similar area in another part of the New York shore, but I think it is best not to divulge that location for obvious reasons (Baldassano, pers. com.)."

Neil Garrick-Maidment, a very successful seahorse breeder in the UK, reports much the same thing, noting that seahorses in the wild seem to thrive amid strong currents:

"Whenever I have dived on Seahorse sites I have always been amazed by the currents and tides that this very fragile looking Seahorse lives in. We often find Seahorses in flat muddy/silt areas nowhere near rocks or weed. These areas are often scoured by strong currents and the Seahorses do well in them and seem completely unperturbed by the current (Garrick-Maidment, pers. com.). In setting up a tank for them I try to remember the feeling I had in those areas and replicate them. I have now started to use wave surge devices, so that the current in the tank, although strong (they seem to thrive in strong currents) varies in its direction (Garrick-Maidment, Jun. 2002)."

Kirk Strawn, who earned his Master of Science thesis studying Hippocampus zosterae in the field, echoes Neil’s thoughts on the matter:

"The aquarist is not giving his seahorses natural conditions when he keeps them in a still-water aquarium. In nature tidal currents, wind, and waves are usually mixing the well aerated surface film water with the deeper water."

Likewise, David Warland, a fish farmer and commercial seahorse breeder in Port Lincoln, Australia, reports he often finds Hippocampus abdominalis perching on the tuna net enclosures at the farm in deep water:

"The Horses that are around the farms have traveled vast distances over plain sand/mud to get to the farms, which are in at least 20 meters of water, and are miles from the nearest land or shallow water (Warland, pers. com.)."

And Jorge Gomezjurado, the Senior Aquarist at the National Aquarium in Baltimore, recommends the following when it comes to water movement:

"I personally believe that current and water dynamics are very important for Syngnathids. In nature they live in areas with active water movement.(i.e., tides in mangrove lagoons and estuaries, coral reefs, kelp forests, etc.). Why don’t we give them the same environmental conditions in captivity? Our small tanks (90 gallons) have large turnovers on an average of 5 gpm (or 300 gph). It is very important that the current is steady and directionally constant, which allows the animals to find a good spot to hold and they will not be pulling in different directions all the time."

Most seahorse keepers feel it’s best to keep the current steady and nonvarying so they can find slack-water areas and sheltered spots downcurrent to hold in when they want to get out of the current. The more brisk the water flow, the more important this becomes. However, in a large aquarium with low to moderate water movement, alternating currents should not present much of a problem, and would help to provide good circulation throughout the tank.

You’ll want to adjust the outflow the filters to eliminate any dead spots or stagnant areas where waste products may tend to accumulate. Good circulation will prevent pockets of harmful anaerobic decay and keep particulate matter suspended in the water column where the filters can remove it from the aquarium. Alternating the direction of the water flow is also helpful, as is increasing surface agitation to improve the oxygenation and facilitate more efficient gas exchange at the air/water interface. A simple air stone anchored just beneath the surface of the water can help to achieve this goal.

Using Powerheads for Additional Water Movement

If the external filter(s) do not provide enough water movement to assure good circulation throughout the aquarium, you can position small powerheads in the tank, strategically placed to provide good water flow wherever there might otherwise be dead spots or stagnant areas. Just make sure that the intake for the powerheads is screened off in order to prevent a curious seahorse from getting its tail sucked up by the powerhead and injured.

For example, along with an external power filter, my seahorse setup also has a 200 gph powerhead with a sponge pre-filter positioned right near the top for surface agitation and extra water movement, with additional small powerheads used as needed to eliminate any dead spots along the substrate or behind the rockwork. I like to give my seahorses as much current as they can handle without getting blown around.

You don’t need to use a large, powerful powerhead to improve the water circulation in your seahorse tank. A small unit will generally suffice as long as it’s positioned properly where it’s most needed, and using a device that automatically sweeps the powerhead back and forth will often allow you to produce much better water movement than a much bigger powerhead that is stationary.

Devices that will automatically alternate the water flow in the aquarium by rotating the water flow from side to side include the Power Sweep power heads by ZooMed, the OSCI-Wave by Bell Marine and the Sea-Swirl by Aquarium Currents.

The Power Sweep power heads have an automatic rotating outlet that can be used as a wave maker. They are inexpensive and come in a number of different sizes to suit most every aquarium but need to be well-maintained to keep them in good working order. In short, the Power Sweep powerhead is an automatic self-rotating wavemaker that comes in three different models, each with a different flow rate, measured in gallons per hour (GPH).

Power Sweep 214 – For aquariums up to 30 gallons (114 liters) with a flow rate of 160 GPH

Power Sweep 226 – For aquariums up to 50 gallons (190 liters) with a flow rate of 190 GPH

Power Sweep 228 – For aquariums up to 75 gallons () with a flow rate of 270 GPH

They all have an adjustable flow rate that will allow you get the desired flow for your particular setup, which is ideal for seahorse tank. They will fit all undergravel filter stem sizes and are an excellent addition to a seahorse setup that is filtered with undergravels, and they also come with a pre-filter for the intake and a mounting bracket with suction cups.

The OSCI-Wave uses an electric motor to control a single powerhead. Powered by a small AC motor, this unit is tank rim mounted and hangs a powerhead 4.5" below the rim of the tank, which it then rotates back and forth. The Bell Marine OSCI-Wave oscillator is a small motor, located inside a 5.5" long, 3" wide 2.5" tall black acrylic box, which is attached to the rim of the tank and suspends a powerhead up to 4.5" below the surface of the water. The box mounts on the frame of the aquarium with an acrylic bracket with 4 nylon screws. The powerhead of your choice is mounted on a paddle which is attached to a plastic shaft, suspended from the box. The motor, almost silently, sweeps the powerhead in a 90 degree arc every 30 seconds. The manufacturer (Bell Marine) recommends the use of Aquarium Systems Maxi-Jet powerheads, due to their small size for the high velocity output, but it can be used with most powerheads.

The Sea-Swirl is a rotating return device. It uses an electric motor to power the rotating return that oscillates the return water from your existing pump or canister filter 90 degrees every 60 seconds. These units are available in three different sizes, are mounted on the rim of the tank, and cannot be submerged. As a result, the Sea-Swirl agitates only the surface water and can’t be adjusted to point toward the bottom of the tank, which is a limiting factor for these units. They must be used with a separate powerhead, water pump, or canister filter.

All of these devices do a good job of increasing surface agitation and maximizing the water movement provided by a single powerhead to further improve water circulation. Which of them will produce the best results for you, if you need to increase the water circulation in your seahorse setup, depends on how you’ve chosen to set up your aquarium, its size, the equipment you already have, and on your available budget. For example, the units that are mounted on the rim of the aquarium can be difficult to mount on a tank with a full aquarium hood. If your local fish store does not carry them, just do a Google search for any of these devices and you will find numerous outlets that offer them online.

Improving the water circulation and surface agitation to increase the oxygenation will raise the levels of dissolved oxygen in the aquarium while eliminating excess CO2 via more efficient offgassing. You may notice that your seahorses become more active and have a better appetite, eating more aggressively, as a result, and elevating the levels of dissolved oxygen and reducing the levels of dissolved CO2 will also help to raise and stabilize the pH of the aquarium at the same time. This is important because the pH of the aquarium tends to drop over time, and low pH can be a contributing factor for gas bubble syndrome.

Providing good water circulation and surface agitation to improve the oxygenation and promote more efficient offgassing at the air/water interface is especially important for seahorses because of their primitive gills. Unlike most teleost (bony) fishes, which have their gills arranged in sheaves like the pages of a book, seahorses have rudimentary gill arches with small powder-puff type gill filaments. Seahorses are said to have "tufted" gills because they appear to be hemispherical clumps of tissue on stems. Their unique, lobed gill filaments (lophobranchs) are arranged in grape-like clusters and have fewer lamellae than other teleost fishes. Because of the difference in the structure and efficiency of their gills, seahorse are unusually vulnerable to hypoxia when CO2 levels are high and/or O2 levels are low, so the diligent seahorse keeper will take full advantage of the measures we have discussed above to improve the dissolved oxygen levels in the aquarium.

The point is that, as long as slack-water retreats are available, the greater seahorses can tolerate far more current than most folks suspect and good circulation is as important for a seahorse setup as any other aquarium. What seahorses lack as swimmers is not agility, but rather stamina (Evans, 1998). They can hold their own against strong currents, but not indefinitely, so low flow areas where they can move out of the current and hold when they want to rest must be provided in addition to good circulation.

In short, if your filtration is not turning over the entire volume of the aquarium a MINIMUM of 5 times per hour, your seahorse setup is undercirculated. With a spray bar return raised above the surface of the water to diffuse the outflow, you can safely achieved much higher turnover rates (> 10 times per hour) without producing too much turbulence or current for seahorses in a tall tank. A waterfall return is another good way to diffuse the output from your filter, and also works well for seahorses. There will be an area of relatively vigorous water movement at one end of the aquarium underneath and nearby the waterfall, while the other end of the tank is a relatively low flow area. (By the same token, however, if the filtration system in your seahorse tank is turning over the entire volume of water much more than five times per hour, it may be too overpowering for the seahorses unless it is diffused by a spray bar or waterfall return.)

As with anything, too much of even a good thing can be undesirable, and too much current can overwhelm the limited swimming ability of Hippocampus. One indication that you may have too much water movement in your seahorse tank is if the seahorses are getting buffeted around by the currents, and whisked away uncontrollably when they tire of fighting the current. Or alternatively, they may stay perched in one place all the time and refuse to swim around and explore their tank for fear of getting swept away by the current if they relax their grip on their hitching posts. So you can get a pretty good gauge of how well the seahorses are able to cope with the water movement than their tank by observing how the current affects the swimming ability.

Likewise, if a mated pair of seahorses is consistently spilling eggs during the copulatory rise, that’s another pretty good indication that there may be too much turbulence or water movement in the upper reaches of their aquarium.

If the seahorses are having difficulty tracking their prey and eating because the current whisks the frozen Mysis past them too quickly to target it accurately and slurp it up, that’s another red flag. Often that situation can be corrected simply by adjusting the output from your filter to reduce the current during feeding time or turning it off altogether while the seahorses are eating.

But as long as your seahorses aren’t getting buffeted around, aren’t routinely dropping eggs during disrupted mating attempts, and aren’t having difficulty targeting their prey and eating, there’s really no such thing as too much water movement. In general, the stronger the water flow, the more important it is to keep the water currents steady and unvarying so the seahorses can establish holding areas in the sheltered spots and low-flow zones without getting blindsided by unpredictable currents. Just make sure your seahorses are not getting trapped against overflows and be sure to screen off the intakes for any powerheads. Powerheads can be switched off at feeding time, if necessary.
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Okay, Monica, that’s the quick rundown on water circulation in his seahorse setup. In your case, the water pump that came with the 38-gallon Innovative Marine Mini Nuvo aquarium system as an output of 476 gallons per hour and turns over the entire water volume of the aquarium around 12-1/2 times every hour, which is too overpowering for the limited swimming ability of the seahorses. You would need to modify that by installing a spray bar return or switching to a smaller water pump that puts out about half as much water every hour.

Best wishes with all your fishes, Monica! Please let me know if I can be of any further service.

Happy Trails!
Pete Giwojna, Ocean Rider Tech Support