Seahorse Club
Aquarium & Livestock

Feed Ezy Frozen Mysis

Seahorse Club
Aquarium & Livestock

Feed Ezy Frozen Mysis

Seahorse Club
Aquarium & Livestock

Feed Ezy Frozen Mysis

Seahorse Club
Aquarium & Livestock

Feed Ezy Frozen Mysis

Seahorse Club
Aquarium & Livestock

Feed Ezy Frozen Mysis

Seahorse Club
Aquarium & Livestock

Feed Ezy Frozen Mysis

baby seahorses!!!

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  • #1314

    HELP! i have purchased 4 mustangs from – one pair a year ago, and another a few weeks ago. i went to feed them this morning and found about 40 babies swimming at the top of my 55 gallon tank!

    i captured them in a clear plastic \"breeder\" container about 4×8\" that is hanging at the top of my tank. i went to the pet store and they gave me freeze dried rotifers to feed them, which i can\’t really tell if they\’re eating or not. also i bought a brine-shrimp hatching kit that i understand they will need to have hatched within the next 3-4 days?

    can anyone give me some advice about if i\’m doing the right thing and what else to do for them? how soon do i need to get these brine hatching? should i keep them in the container? i don\’t really have another tank i can put them in safely right now.

    i understand seahorse fry are very hard to raise, and the guy at the pet store said there was virtually no chance any of them would survive my first attempt at raising them, but i would certainly like to try!

    Pete Giwojna

    Dear hobbyist:

    Congratulations on your unexpected brood of babies!

    The guy from the pet store was right — there is a always a steep learning curve when it comes to rearing the newborns, and it’s quite common — perhaps even the rule — for the home breeder to lose the entire brood during his first few attempts at rearing. But as you refine your methods and become more proficient at providing suitable live foods for the newborns and work out the feeding regimen that’s most efficient for your particular circumstances, your results will get better. You will have more of the fry surviving for longer periods, until eventually you are able to raise a few of the fry from a few of the broods to maturity. It’s just a matter of patience and hard work, and now that your Mustangs have begun breeding, they will produce a new brood for you every month or so, so you are going to have lots of opportunities to practice and improve.

    It’s very unlikely that the newborns are going to eat the freeze-dried rotifers. Some breeders report. Limited success rearing seahorse fry on nonliving foods such as freeze-dried or frozen Cyclop-Eze or preserved zooplankton, but the vast majority of newborns will not except such offerings, at least initially, and losses are typically very, very high for those who have tried such shortcuts. The non-living food simply doesn’t move right, and usually fails to elicit a feeding response from the fry. So the freeze-dried rotifers are not likely to be helpful at all at this point.

    But don’t panic — the fry are born with a limited yolk supply that can sustain them for the first 24 hours, so they needn’t be fed immediately and that gives you a little time to get your brine shrimp hatcheries going, as I’ll explain in greater detail below.

    I would recommend providing the newborns with 3-5 feedings of newly-hatched Artemia spaced 2-3 hours apart for best results. If you search this forum for the phrase "fry feeding schedule," you’ll find a lot of additional information regarding successful feeding regimens for keeping up with the voracious appetites of seahorse fry.

    All seahorse babies are challenging to raise and your Mustangs (Hippocampus erectus) are no exception. How difficult or challenging they may be depends on the type of seahorses you have. Two main factors determine how easy or hard seahorse fry are to raise: (1) their size at birth and (2) whether or not they undergo a prolonged pelagic phase. The bigger and better developed the newborns are, the easier they are to raise. Seahorse fry whose average length at birth is 10 mm (0.4 inches) or more are able to take enriched Artemia as their first foods and are relatively easy to rear. Seahorse fry that are significantly smaller than 10 mm (0.4 inches) at birth need to be started on smaller foods that are more difficult to provide in copious amounts on a daily basis, such as rotifers, copepods, and larval Mysis, making them more difficult to raise. Likewise, seahorse fry that undergo an extended pelagic phase, during which they drift freely with the plankton, are much more troublesome to raise than benthic seahorse fry, which orient to the substrate and seek out hitching posts straightaway. The pelagic fry are difficult because the surface huggers tend to gulp air and suffer fatal buoyancy problems, and may even become entrapped by surface tension. As a result, most hobbyists find that mortality is very high during the pelagic phase.

    The easiest seahorse fry to rear are therefore benthic fry that are large and well developed at birth. Dwarf seahorses or Pixies (Hippocampus zosterae) fall into this category, and indeed many hobbyists have closed the life cycle with zosterae. The most difficult seahorse fry to raise are relatively small and underdeveloped at birth, and must pass through a lengthy pelagic stage. Brazilian seahorse fry (Hippocampus reidi) are a good example of this category, and are notoriously difficult to raise.

    Ocean Riders span the gamut in that regard, including both those species that are the easiest of all to raise and those that are the most difficult to rear, and everything in between. At the one extreme, there are Mo’Olios, which produce very large broods of tiny fry that are barely 3-4 mm at birth and remain pelagic all their lives, even as adults. Mo’Olios are very challenging for even expert aquaculturists with state-of-the-art facilities to raise. Brazileros and Gigantes likewise have enormous broods of relatively small (6-7 mm) fry that undergo a rather protracted pelagic phase lasting weeks. The average hobbyist would still be hard-pressed to regularly raise any of their fry.

    At the other extreme, there are Pixies, which produce small broods of large, well-developed benthic fry that hitch from day one. Pixies (H. zosterae) are probably the easiest seahorses to rear, and no doubt more hobbyists have closed the life cycle with this species than all other seahorses combined. Spikeys (Hippocampus barbouri) and Zulu-lulus (H. capensis) likewise produce large benthic babies that are relatively easy to raise. Most of the remaining Ocean Rider types (Mustangs, Sunbursts, Pintos, Fire Reds) produce fry that are fairly good sized (about 8-10 mm) and whose pelagic phase is fairly short (several days rather than weeks), and which are therefore intermediate in difficulty.

    In short, your Mustangs (H. erectus) will produce fry that are moderately difficult to raise. They will be able to eat newly hatched brine shrimp right away, but they will go through a pelagic phase lasting anywhere from several days to a week or two. The link below will take you to an article that discusses how to rear them in greater detail (they are suitable for the "easy" rearing method outlined in the article). It will explain how to set up a basic nursery tank and culture the live foods you need to feed the newborns:

    Click here: – Seahorse, Sea Life, Marine Life, Aquafarm Sales, Feeds and Accessories – Nutrition – Feeding & Rearing the Fry


    As a Mustang keeper, you may also find the following online articles on rearing H. erectus to be especially helpful:




    Fry Development Cycle – From Egg to Horse

    If you don’t have a separate tank you can set up as a nursery, then you might want to try hanging a breeder net designed for livebearing fish such as mollies and guppies, or a perforated "critter keeper," inside your 55-gallon aquarium to contain the newborns an act as a makeshift nursery. This will create what is known as an in-tank nursery, which is an arrangement that can be quite effective as long as you keep them scrupulously clean, as discussed below:

    The In-Tank Nursery.

    In-tank nurseries enjoy all the advantages of divided nurseries and then some. For example, like divided nurseries, the tank-within-a-tank design makes it much easier to provide seahorse fry with stable conditions and optimum water quality, vastly increases filtration and equipment options, simplifies maintenance and offers enormous versatility. The idea behind the in-tank nursery is to confine the seahorse fry in a small, flow-through enclosure that can then be attached securely inside a larger aquarium. The in-tank fry enclosure must allow water to pass through it freely but not fry food such as copepods, rotifers or Artemia nauplii. The enclosure thus allows the food to be concentrated in a small space to maintain the proper feeding density, while at the same time providing the fry with all the benefits of living in a much larger volume of water. This includes greater stability in terms of water temp, pH, oxygen levels, salinity and so on.

    But by far the biggest advantage of the in-tank nursery is the superior water quality it provides. The larger tanks that accommodate the fry enclosures are normally in the 10-20 gallon range, but there is no upper limit to the size of the host aquarium — the bigger, the better. Of course, for starters, the larger volume of water is naturally more resistant to pollution from the mass consumption and elimination one must deal with when rearing seahorse fry. But more importantly, with the fry safely sheltered in their nursery, the main tank can be equipped with any kind of filtration and filter media you can think of to improve water quality or safeguard the health of the fry. This includes heaters, sponge filters, inside box filters or external power filters with activated carbon, polyfilter pads, or ion-exchange resins, micron-level mechanical filtration, bio-wheels, wet/dry filtration, protein skimmers, UV sterilizers, ozonizers — you name it. Airstones, bubble wands, powerheads, filters and the like can operated full blast without worrying that they’ll buffet the fragile fry or that they filters may ‘eat’ the newborns or consume all their food. Use your imagination — anything goes!

    Water quality benefits as a result, and the added filtration reduces the need for frequent water changes. When substantial water changes are called for, the main tank makes the whole process easier.

    The first in-tank nurseries were ready-made breeder nets intended for livebearing freshwater tropicals (Abbott, 2003). I know several hobbyists who use breeder nets for rearing dwarf seahorse fry. They tend to get a bit dirtier than bare-bottomed nurseries (uneaten brine shrimp and fecal pellets will accumulate on the netting and cling to the mesh) so you’ll need to be diligent about siphoning the netting clean of such wastes and debris, just as you would be when cleaning the glass of a bare-bottome nursery. The dirty water should be replaced with cleaned, newly mixed saltwater you’ve prepared and aged/aerated overnight. These small water changes will help maintain good water quality in the nursery.

    Many hobbyists who used these breeder nets for rearing fry keep two of the nets, one which is in use as a nursery, and a clean spare which they transfer the fry into when the breeder net that’s currently in use gets too dirty despite the siphoning. The dirty net is then cleaned and disinfected thoroughly and held in reserve until the other breeder net needs to be replaced. The two breeder nets are then switched back and forth as often as necessary to assure that fry are always contained within a reasonably clean enclosure.

    These breeder nets worked very well for dwarf seahorses, which produce small numbers of babies (Abbott, 2003), but they are not well suited for the huge broods of fry many of the greater seahorses produce. Hobbyists soon began to improvise in order to overcome the limitations of such breeder nets and accommodate larger broods in their fry enclosures. Breeders began to experiment with in-tank refugia, “critter keepers,” and various plastic containers to meet their needs. They modified these by drilling them full of holes and covering the holes with plastic mesh. If necessary, an airline is added to the fry enclosure for better circulation and a drip line brings filtered water in from the main tank or an external power filter.

    The versatility of in-tank nurseries is one of their biggest assets. They allow almost any existing aquarium to “host” a fry enclosure and there is also great flexibility in the design of the inner nursery tank. They can easily be modified to accommodate either benthic or pelagic seahorse fry, and multiple in-tank nurseries can be housed in one big main aquarium. Endless variations on this basic concept are possible. The in-tank nursery is simply a much more versatile and adaptable design than the divided nurseries that preceded it.

    For starters, here are some tips on hatching and enriching the baby brine shrimp you’ll need to feed the newborns:

    Hatching Out Brine Shrimp (Artemia)

    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 or brine solution 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. A temperature of 80-82 degrees F is optimum for hatching brine shrimp.

    The eggs will begin hatching after 1-24 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 6-8 hours after hatching, and the food value of the nauplii deteriorates steadily as the yolk sac is consumed. Once it has been exhausted after about 8 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 seahorse fry, 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.

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

    Click here: Brine Shrimp Technical Information 1

    The best eggs or cysts to use for your brine shrimp factory are decapsulated eggs which have had their hard, outer shells stripped away. These shell-less eggs have many advantages over ordinary Artemia cysts. For starters, they simplify the task of separating the live nauplii from the unhatched eggs, since there are no empty shells, and the decapsulated eggs eliminate the possibility of clogged intestines due to the indigestible cysts. Secondly, the decapsulation process destroys virtually all known pathogenic organisms. Since the shell-less eggs have been disinfected, there is much less risk of introducing disease or parasites to the aquarium when you feed your seahorses with brine shrimp from decapsulated cysts. More importantly, the nauplii produced from decapsulated eggs have greater caloric value than the nauplii from unaltered cysts. This is because the nauplii from decapsulated eggs do not have to waste energy struggling to break free of their shells, and thus emerge with 20% greater food value, primarily in the form of additional amino acids and essential fatty acids. This extra nutritional value can make a crucial difference to the rapidly growing seahorses.

    Decapsulated brine shrimp eggs are now available from some manufacturers. Although the shell-less eggs are expensive to buy, it is easy for the serious hobbyist to decapsulate his own brine shrimp eggs at home.

    Decapsulating Brine Shrimp Eggs.

    Decapsulating brine shrimp cysts — the process of dissolving away their hard outer shell — may sound intimidating at first and may seem awkward when you first attempt it. No doubt you will have these instructions open, your eyes glued to the page, with all of your supplies at the ready the first few times you perform this procedure. Relax, this is not difficult at all, and after you’ve done it a couple of times, you will see how truly easy it is and realize decapping is well worth the extra few steps. I will walk you through each numbered step. Measurements do not have to be exact. Regular strength bleach is best, but ultra bleach can be used at lesser portions. You can estimate this yourself. Decapsulating your cysts is beneficial for a number of reasons:

    · Reduces the risk of hydroids.

    · Removes the outer shell, which means less mess and no fouling of your tank.

    · Eliminates intestinal blockages from accidental ingestion of indigestible shells.

    · Kills off any and all unwanted contaminants.

    · Slightly quicker hatching times.

    · Better hatch rates.

    · Increased nutritional value secondary to less energy expenditure during hatching.

    Supplies Needed for Decapsulating:

    · Brine shrimp net

    · Air pump

    · plastic clip or paper clip wrapped in baggie to clip airline into the container

    · Approximately 2 teaspoons brine cysts.

    · Approximately 2/3 cup of bleach

    · Approximately 2 cups of water


    1. Pour your water into a container and clip airline tubing to the side. (No air stone is needed for this). This will keep the cysts in motion. Allow the cysts to aerate this way for approximately 1 hour or a little more.

    2. Add in your bleach and continue aerating. As the outer shell gradually dissolves, the eggs go through a series of color changes from brown to gray to white and finally to orange–the color of the nauplii within. This process takes about 7 minutes. The decapsulation process is complete when your cysts become an orange-yellowish color.

    3. Pour decapsulated eggs into a brine shrimp net. Add a dechlorination product if you want and rinse until you no longer smell bleach.

    4. Drop eggs into your hatching container. You can also refrigerate eggs for about 1 week prior to use in a supersaturated saline solution.

    You will need to either feed the bbs to your seahorses immediately after hatching, when their yolk supply is virtually intact and they have their maximum nutritional value, or feed bbs that are 2-days old or older and have been enriched prior to feeding.

    Best of luck with your bonus babies! Keep a close eye on your Mustangs for the next day or two, since it is typical for a stallion to remate within 24 hours or so of delivering his latest brood. If you’re lucky, you will be able to witness the fascinating mating ritual and transfer of the eggs.

    Happy Trails!
    Pete Giwojna


    thanks for all the great info … i’ve been doing as much research as time permits this week and i’m a little overwhelmed. opinions seem to differ dramatically, and most articles assume i know too much to start with!

    on the positive side though, after day 4 i have only lost one baby. all the others are thriving, hitching to the plants i added to their "in tank" nursery, and eating newly hatched baby brine enthusiastically 3-4 times a day.

    my next step is to figure out how to "enrich" my hatchlings before i feed them to the seahorses … and i think i should start doing this very soon? i have vibrance that i use to "enrich" the frozen mysis for the adults … can i use this to enrich the brine? it seems that selco is the product of choice that i may need to order instead. if i use vibrance – do i just add add it to the day+ old harvested shrimp for them to ingest, or is the idea just to coat the shrimp with this stuff before feeding like i do with the frozen mysis?

    at this point, i’ve been just dumping whatever is left of the brine shrimp after 2 days (i figure 1 day to hatch, 1 day to grow beyond any nutritional value?).

    and all of this is just to gain experience so that some of the NEXT batch may survive? how discouraging…

    anyway, sorry for the stupid quesitons … but if i wait until i can sort thru all the info on the forums, these little guys won’t stand a chance!!

    Pete Giwojna

    Dear hobbyist:

    You’re very welcome! It sounds like you’re doing a great job of absorbing all of the information and learning as you go — so far, so good.

    As you know, Artemia nauplii (baby brine shrimp) are filter feeders that will ingest whatever is suspended in the water with them. This makes it easy to enrich the nauplii with everything from Vibrance to yeast cells to microalgae to fatty acids and vitamins and minerals, greatly enhancing their nutritional profile in the process.

    The problem with such traditional enrichment methods is that only older nauplii at advanced stages of development can be fortified this way. Newly hatched brine shrimp nauplii (1st instar) lack mouthparts and derive their nourishment from a yolk sac. They are incapable of ingesting particles in the water. Consequently, only bigger nauplii that have molted once or twice (2nd instar and beyond) are suitable for this type of enrichment. This is a serious drawback since these older, larger Artemia nauplii have already grown beyond the size that most newborn seahorse fry are capable of swallowing.

    Many breeders feel that the best way around this problem, is to feed newly-hatched brine shrimp without any enrichment that all. The newly hatched brine shrimp (Artemia nauplii) have a large yolk sac that sustains them until they develop mouthparts, and the nutrition contained in the exact makes them a highly nutritious meal for dwarf seahorses without any need for enrichment. The trick is to set up to separate brine shrimp hatcheries and then alternate which one you harvest the bbs from each time you feed the dwarf seahorses. This will ensure that you are feeding brine shrimp that have recently emerged from their egg cases or cysts, and are therefore at the peak of their nutritional value with their yolk supply largely intact.

    Decapsulating the brine shrimp before you hatch it produces the best results because the baby brine shrimp don’t have to use up any of their energy reserves or yolk supply struggling to break free from their egg cases.

    Here’s an article from Neil Garrick-Maidment, a very successful seahorse breeder in the UK, that explains how to use this method for best results:

    <Open quote>
    Rearing Seahorse Fry on Artemia.

    Neil Garrick-Maidment


    The Seahorse Trust.

    It has long been thought that rearing Seahorse fry on Artemia is impossible because they do not hold enough nutritional value. This is partially true but if dealt with in the correct way then artemia can be used very successfully.

    Artemia is highly nutritious when it is first hatched out but the nutritional value drops very quickly to virtually nothing within 3 hours; added to this the carapace (shell) hardens during this 3 hour period and makes it very difficult to digest by all but the most harden fish fry.

    The traditional way of cultivating artemia is to put the eggs into a pot of seawater, aerated at 80’ and wait for them to hatch 24 hours later. This one pot of artemia is usually used for a 24 hour period and quite often is stored in a refrigerator until it is used; this is where the nutritional problems occur unless the artemia is enriched. Once enriched (often for another 24 hours as the mouth parts do not form until 10 hours old) it often proves to be a poor source of food as it is by this point either too large or the carapace (shell ) of the artemia is too hard. By being too large or having too hard a carapace it means that fish fry like Seahorses cannot digest it as they have an extremely poor digestive system; which is not long enough to allow it to digest the hard carapace and derive enough nutrition from the naupilli. .

    By changing the protocol of hatching the artemia it is possible to use it as a highly successful form of food especially for Seahorses; the only draw back with this system is that it is labour intensive.

    The set up:

    We use a 5 pot system for the hatchery, each one labelled 1 to 5; all five pots sit in a glass fish tank with 4 inches of water in it. This water is heated by heater/thermostat to 80’ and each of the pots is heated in turn by this hot water. Each pot also has an airline with an airstone into it.

    The protocol:

    Start with pot 1 and fill it with saltwater and add your artemia eggs (you can use unshelled eggs to increase the nutritional value higher.). 2 hours later repeat the process with pot 2 and then each 2 hours after repeat with the rest of the pots; it is possible to use more pots if your needs require it.

    If you have set up pot 1 at 8am then 24 hours later at 8am the artemia should have just hatched out, this is then the time to feed pot one to your fry; it is crucial that the time between hatching out and feeding is kept to a minimum.

    Harvest the artemia by letting the pot stand and the artemia will sink to the bottom and the egg shells will rise to the surface. Use a siphon through a very fine mesh trap to siphon them out of the pot, once you have enough artemia then give them a quick wash under a freshwater tap and then feed the artemia to your Seahorse fry.

    It is crucial that you only feed a small amount of artemia to the Seahorse fry; enough to be eaten by the time the next pot is fed to the fry (2 hours later).

    Once you have fed this pot of artemia to the fry do not be tempted to keep what’s left over, use it for some other fish species but don’t be tempted to feed it later on to the Seahorse fry.

    Once you have harvested pot 1 immediately set it up again ready for the next 24 hour period.

    Every time you go to feed the next pot of artemia be sure to siphon the tank of any debris from the bottom of the tank and crucially remove any left over artemia from the tank. This can be done by putting a light to the side of the tank to attract the artemia to it then siphon them from the tank. This is important as you do not want the Seahorse fry to be eating older hardened and nutritionally low value artemia.

    After feeding the artemia remember to top up the water you have removed from the fry tank, this way you will be changing water throughout the day lessening the build up of harmful nitrites and ammonia in the water which is better for the Seahorse fry.

    As a side note we usually use water from the adult’s tank to replace and indeed start up the fry tank; this is already filtered and as we use natural seawater it is a better source of water for the fry; they appear to do better in natural seawater than artificial.

    These steps should be repeated every 2 hours with pots 2 then 3 then 4 then 5 and any others you add to the system.

    This process should be repeated on time every 2 hours as the age of the artemia naupilli is important for its nutritional value and carapace hardness.

    <Close quote>

    So, basically, you will need to either feed the bbs to your seahorses immediately after hatching, when their yolk supply is virtually intact and they have their maximum nutritional value, or feed bbs that are 2-days old or older and have been enriched prior to feeding. If you want to go that route once the newborns are large enough to accept the second instar Artemia nauplii, the lipid-rich Vibrance 1 formulation is ideal for this but the no-fat Vibrance 2 formula should be avoided.

    Here are the instructions for enriching brine shrimp that are more than one day old and have developed their mouthparts. As I mentioned, and the original Vibrance formula that is rich in highly unsaturated fatty acids and other lipids (i.e., Vibrance I) works best for fortified brine shrimp:

    Enriching Artemia with Vibrance I

    For enriching or "gut packing" live Artemia (brine shrimp), or other live shrimp or live food of all sizes. Blend 1 teaspoon of Vibrance into 1 cup of water for 3 minutes. Add this to the live food vessel for 30 minutes, or until you see the gut of the animal turn red. Rinse the animals with clean salt water and feed immediately to your seahorses or other fish.

    When I am gutloading adult brine shrimp either to bioencapsulate medications or to enrich the brine shrimp hired to feeding I soak them in freshwater for around 30 minutes as explained below.

    Soak the adult brine shrimp in freshwater treated with the antibiotic or the enrichment formulation of your choice for 15-30 minutes and then feed the gut-loaded shrimp to your seahorses immediately. (Don’t let your pumps and filters "eat" all the brine shrimp!)

    The brine shrimp are soaked in freshwater, not saltwater, because in theory the increased osmotic pressure of the freshwater helps the antibiotic solution or enrichment product move into their bodies via osmosis. But in fact nobody knows for sure whether the antibiotic/enrichment is diffusing into the brine shrimp or they are ingesting it in very fine particles (brine shrimp are filter feeders and will take in whatever is suspended in the water with them) or whether the brine shrimp merely become coated with the medication or enrichment formula while they are soaking in it. But that’s not important — all that really matters is that gut-loading adult brine shrimp in this manner is very effective.

    Best of luck keeping up with the endless appetites of your seahorse fry!

    Happy Trails!
    Pete Giwojna


    well, 4 weeks later and i still have 42 babies. i’ve lost a total of 10 so far, 6 in the first week, and 4 more at about 2 1/2 weeks. they are eating mostly 1-2 day old brine shrimp and are starting to occasionally eat small amounts of frozen cyclops. they ignore mysis – i think it’s still too big. 3 more questions:

    1. i still have them in an "in tank" nursery, although i have upgraded them to a 1-gallon container. i’m considering putting in a tank divider soon to give them more room in the tank. can you give me an idea how much room they will need as they grow, and how many i will ultimately be able to keep in a 55 gallon tank?

    2. at what point should i be expecting all these little guys to die?? from everything i’ve heard, i didn’t expect them to survive the first week, much less the first month. or is it typical for them to survive a couple of months, but still die before becoming fully grown? that would really stink, as my kids are starting to NAME them…

    3. there is a "runt" among them (his name is clifford) that is literally about half the size of the rest. he seems healthy and is eating well, just not growing as fast. should i isolate him from the others to make sure he’s getting enough to eat, or just leave well enough alone?

    Pete Giwojna

    Dear hobbyist:

    Congratulations on getting so many of the seahorse fry past the four-week mark! You are doing very well for your first attempt at rearing. I’ll do my best to answer your additional questions one-by-one below:

    1. i still have them in an in tank nursery, although i have upgraded them to a 1-gallon container. i’m considering putting in a tank divider soon to give them more room in the tank. can you give me an idea how much room they will need as they grow, and how many i will ultimately be able to keep in a 55 gallon tank?

    It is customary to transfer the seahorse fry to a series of larger nurseries and grow out tanks as they mature, so the appropriate stocking density for the youngsters depends upon their age and size. For example, the recommended stocking density for pelagic seahorse fry such as Mustangs or Sunbursts is no more than 6 fry per liter, or a maximum stocking density of about 25 fry per gallon. If your nursery tank holds 10 gallons, for example, it can hold about 200 newborns when stocked to capacity, and for best results I would keep it understocked.

    Typically by the end of their third week, the fry have grown enough that there stocking density needs to be reduced to maintain adequate water quality and promote further growth. Thus, at this age, the appropriate stocking density for the juveniles is about 7-10 fry per gallon of water.

    Ordinarily all of the fry have successfully made the transition to minced Mysis by the age of 7-8 weeks. At this stage, the juveniles are then transferred to larger grow-out tanks for further rearing at a stocking density of 3-4 per gallon.

    By the age of about 12-weeks old, the first indications of pouch development may appear. This takes the form of a darkened patch of skin where the pouch will eventually develop (i.e., a nascent pouch is not present at this stage of development, just a patch of pigment). You’ll want to achieve a stocking density of about 2-3 of the youngsters per gallon for three-month-old seahorse fry at this stage of development.

    The juvenile seahorses should be segregated by sex as soon as you can accurately determine their gender if you want to practice selective breeding. That allows you to pair off seahorses with the particular traits you want to encourage in the next generation, and the recommended stocking density for sexually mature H. erectus is one pair per 10 gallons. So you’re 55-gallon aquarium could safely accommodate five pairs or about 10 individual adult seahorses.

    2. at what point should i be expecting all these little guys to die?? from everything i’ve heard, i didn’t expect them to survive the first week, much less the first month. or is it typical for them to survive a couple of months, but still die before becoming fully grown? that would really stink, as my kids are starting to NAME them…

    In general, mortality rates among the newborns and juveniles decrease steadily as they grow, so the older the juveniles become, the greater the chances that they will survive and mature. However, there are a couple of high risk periods in which the mortality rate spikes upwards. The first of these is the pelagic phase, which may last anywhere from a few days to a couple of weeks or more with Hippocampus erectus fry. There tend to be heavy losses due to "floaters" and "surface huggers" during this free-swimming planktonic stage of life. Losses also tend to increase during the transition phases when the juveniles are making the changeover from one type of live food to another, and especially when they are being weaned off of live foods onto frozen Mysis. Some of the fry seem to have a difficult time adjusting to such changes in their diet, and simply fail to thrive as a result. But once the juveniles have made that transition to frozen foods, their mortality rate drops again and their chances of surviving to adulthood increase accordingly.

    3. there is a runt among them (his name is clifford) that is literally about half the size of the rest. he seems healthy and is eating well, just not growing as fast. should i isolate him from the others to make sure he’s getting enough to eat, or just leave well enough alone?

    Its normal for a few undersized individuals to fall behind the others as the fry grow. You will notice that the fry in every brood exhibit a range of sizes (Giwojna, Jan. 1997). The largest individuals may be almost twice the length of the smallest of the fry. Such "runts" are at a serious disadvantage compared to their larger siblings primarily because their bigger brethren benefit from increased feeding opportunities (Giwojna, Jan. 1997). Not only can they swallow larger prey, they can swim further with less expenditure of energy (Giwojna, Jan. 1997). This allows them to feed on a greater range of potential prey and to capture food more efficiently than the small fry. So if you want Clifford to survive, it’s probably best to separate him from his bigger brethren so that he won’t have to compete with them for food.

    Best of luck keeping up with the endless appetites of your seahorse fry and weaning them onto frozen foods as they grow. Keep up the good work!

    Happy Trails!
    Pete Giwojna


    you were indeed correct about the spike in mortality rates … at a little over 3 months, i am down to only 2 babies. i am feeding them exclusively frozen mysis. one of them is thriving and looks great. the other is much smaller in comparison and seemed to be not eating as well, starting a few weeks ago. he appears to have trouble swimming where he intends to go, bumps into things, and frequently has to make numerous attempts to get each piece of food – he repeatedly snaps at it and misses.

    sadly, i started noticing similar behaviour in one of the adults seahorses, and i just found her dead this evening. of the 3 remaining adults, 2 of them aren’t acting quite right. it’s difficult to describe, but they just seem to have difficulty feeding, and are not moving around quite normally. i have tested and retested everything i know to test. there are no traces of nitrates/nitrites/amonia – temp and salinity are normal. i have introduced nothing new into the tank since before the babies were born (unless you count the billions of baby brine i fed the newborns). please let me know if you have any idea what may be happening.

    a few other, less critical, questions:

    1. i have not discovered any new babies since the originals over 3 months ago. is it likely that they are continuing to breed, but that it was just a fluke that i happened to see them the one time before they became lost?

    2. do you know how old the mustangs are typically when you guys sell them? how long do they usually live? when do they become full-sized? the babies i have now are not anywhere CLOSE to full grown.

    3. my tank is completely overgrown with plants. it looks pretty, keeps the algae under control, and the seahorses seem to love having all the places to hide and hitch onto. i’ve always thought plants were great for an aquarium, but can you have too much of a good thing?

    Pete Giwojna

    Dear hobbyist:

    I am very sorry to hear about the increased mortality among your juvenile seahorses and the loss of the adult female.

    It’s very difficult to say what may be wrong with so little to go on, but I would be happy to share my thoughts with you in that regard. The unusual symptoms (disorientation and a loss of motor skills and coordination) you describe may possibly be due to accidental poisoning or some other environmental disease.

    Hobbyists sometimes see neurological symptoms like that under hypoxic conditions when seahorses have been deprived of oxygen for too long. However, it’s unlikely that your seahorses could be suffering neurological symptoms from a lack of oxygen due to hypoxic conditions without showing some signs of rapid breathing, and you didn’t mention any signs of respiratory distress in your message.

    So it’s more likely that some sort of toxin or contaminant may have found its way into your aquarium accidentally. To investigate that possibility, let’s review some of the environmental diseases that can affect seahorses, including heavy metal poisoning, which can produce symptoms that are very similar to the behavior you describe:

    Environmental Diseases Associated with Water Quality

    Heavy metal poisoning is an environmental disease hobbyists must sometimes contend with. Even tiny concentrations of heavy metals are deadly to marine fish and invertebrates. This used to be a common cause for concern among marine aquarists when steel-framed aquariums were commonplace, but the advent of all-glass tanks and acrylic aquaria have greatly reduced such problems.

    The chief offender nowadays is copper, which usually becomes a problem when the hobbyist overdoses the tank with a copper-based medication (Indiviglio, 2002). Other times copper enters the aquarium in tap water used for water changes or topping off the tank. The copper is leached into the tap water from copper pipes and plumbing (Indiviglio, 2002).

    Other heavy metals (iron, lead, and aluminum) sometimes also present a problem when they are accidentally introduced to the aquarium in rocks, gravel, ornaments or decorations. Some of rocks and gravel sold (e.g., red flint) for freshwater use are unsafe in marine tanks because of a high metal content. The same is true for many aquarium ornaments and decorations (Giwojna, 1990). Be especially wary when purchasing artificial plastic plants for the aquarium. Stick with calcareous rocks and gravel and make certain any ornaments or plastic plants you consider are designed for use in marine aquariums and certified to be safe.

    Even the popular sponge or foam filters are often a hazard. Many of them contain metal weights as ballast to hold them on the bottom, which is fine in freshwater but can be deadly in a saltwater setup when the metal slugs corrode and leach heavy metal ions into the water.

    Seahorses suffering from heavy metal poisoning will act as if they are falling-down drunk. They will be listless and loggy, and if they attempt to move, they will be disoriented, bump blindly into things, and have great difficulty maintaining their normal equilibrium and balance (Giwojna, 1990). If they attempt to eat, they will be unable to target the food items properly and appear uncoordinated when they try to slurp up their prey. And as their condition worsens, they will begin breathing hard and fast.

    Treatment is to get the seahorses into clean saltwater ASAP, identify the source of contamination and eliminate it, and change out the water in the main tank. Polyfilter pads pull out copper and many heavy metals and may be especially useful in such a situation.

    Contamination of the aquarium water with household chemicals is another common problem for the hobbyist (Indiviglio, 2002). Avoid using anything that gives off strong fumes anywhere near your aquarium! This includes bleach, paint, lacquer, varnish, paint thinner, turpentine, insect sprays, bug bombs, pesticides, hairy spray, cigarette smoke, and household cleaners of all kinds (Giwojna, 1990). Even if the aquarium is tightly covered or sealed with plastic, airborne contaminants from fumes and aerosols will still be pumped into the aquarium from the air pumps (Indiviglio, 2002). To prevent this from happening when you must use such products near an aquarium that cannot be moved, disconnect the air pumps first and work only in well-ventilated area. Use submersible powerheads to maintain circulation in the covered aquarium, work fast, and air out the room thoroughly before you reconnect the air supply.

    Medicating the aquarium is the worst possible thing you can do when seahorses are suffering from diseases related to water quality or environmental problems such as the toxic conditions described above (Giwojna, 1990). Afflictions such as these are not caused by parasites or pathogens, so medicating the tank not only fails to address the problem, it actually makes matters worse (Giwojna, 1990). Chemotherapeutic agents can be harsh on the seahorses, especially when they are already weakened due to poor water quality or actual poisoning. Worse yet, they are often hard on the biofilter as well and apt to further degrade water quality by killing off beneficial Nitrobacter and Nitrosomonas bacteria.

    Therefore, when accidental poisoning may have occurred, a series of water changes combined with activated carbon filtration and the use of Poly-Filter pads is the best treatment option, and that’s what I would suggest in this case.

    A water change and aquarium clean up is a good place to start whenever you suspect your seahorses may be having a problem. In most cases, the surest way to improve your water quality and correct the situation is to combine a 25%-50% water change with a thorough aquarium clean up. Siphon around the base of your rockwork and decorations, vacuum the top 1/2 inch of the sand or gravel, rinse or replace your prefilter, and administer a general system cleaning. The idea is to remove any accumulated excess organic material in the sand/gravel bed, top of the filter, or tank that could degrade your water quality, serve as a breeding ground for bacteria or a reservoir for disease, or otherwise be stressing your seahorses. [Note: when cleaning the filter and vacuuming the substrate, your goal is to remove excess organic wastes WITHOUT disturbing the balance of the nitrifying bacteria. Do not dismantle the entire filter, overhaul your entire filter system in one fell swoop, or clean your primary filtration system too zealously or you may impair your biological filtration.]

    At first glance your aquarium parameters may look great, but there are some water quality issues that are difficult to detect with standard tests, such as a decrease in dissolved 02, transitory ammonia/nitrite spikes following a heavy feeding, pH drift, or the gradual accumulation of detritus. A water change and cleanup is a simple preventative measure that can help defuse those kinds of hidden factors before they become a problem and stress out your seahorses. These simple measures may restore your water quality and correct the source of the stress before your seahorses become seriously ill and require treatment.

    In addition, I suggest that you drop the specific gravity in your aquarium down to 1.015 as soon as possible. Lowering the salinity in the aquarium can have a beneficial effect in situations like this for a number of reasons. For one thing, it will make it easier for the seahorses to osmoregulate, helping them to build up their strength.

    Seahorses have primitive aglomerular (having tubules but no glomeruli) kidneys, whose primary function is to filter waste from the blood (Evans, 1998). The seahorse’s kidneys are also hard at work maintaining its blood and tissues at the proper osmotic concentration at all times (Seahorse Anatomy, 2004). This is necessary because seahorses live in seawater that is four times saltier than their blood and body fluids, and they are constantly losing water via osmosis across their gills, through their skin, and in their urine as a result (Kollman, 1998). Marine fish risk dehydration because salt cannot diffuse into their bodies but water is being continual lost to the concentrated seawater that surrounds them ((Kollman, 1998).

    To compensate for this, marine fish drink seawater continuously to replace lost fluids and then excrete the excess salts they have taken in through the kidneys, in their feces, and from their gills (Kollman, 1998). As a result, their kidneys produce a very concentrated, salty urine (Kollman, 1998). Expelling excess salt this way is very energetically demanding and comes at a high metabolic cost because the salts must be pumped out of their bodies against a strong pressure gradient (Kollman, 1998). Lowering the salinity as in the aquarium can therefore help ailing seahorses to maintain their energy reserves, giving them a better chance to recover.

    Reducing the salinity also increases the amount of dissolved gases the aquarium water can hold. This helps protect against gas supersaturation and increases the levels of dissolved oxygen, helping the seahorses to breathe.

    And reducing the specific gravity to 1.015 also protects the seahorses against many protozoan parasites and ectoparasites, which is another potential problem that hyposalinity can set right.

    When the salinity in the aquarium is lowered, it is done as if performing a normal water change, except that the replacement water is simply treated tap or RO water without the salt (Don Carner, pers. com.). (If the replacement water is RO/DI or other softened source, then a buffering agent should be employed to prevent pH and alkalinity drops; Thiel, 2003.) Make sure the freshwater you add is thoroughly mixed with the remaining saltwater in the tank as you proceed. This will assure that your salinity/specific gravity readings are accurate. Monitor the lowering closely so as to not reduce it too fast. Achieving the desired specific gravity of 1.015 over a period of several hours is fine (Don Carner, pers. com.). The bacteria colony in the biofilter will not be adversely affected and the seahorses will handle the change in salinity without missing a beat. Any delicate invertebrates that may not tolerate a change in salinity should be removed for safekeeping before hand. (If you contact me off list at [email protected], I will provide you with a lot more information on the benefits of hyposalinity at how to administer it safely and easily.)

    In summation, I would recommend performing one or more water changes in conjunction with a judicious aquarium cleaning, adding activated carbon and a polyfilter pad to your external filter to remove any possible toxins are contaminants that may have found their way into your seahorse setup, and reducing the specific gravity in the tank to 1.015 to help the seahorses recover.

    I’ll do my best to answer your remaining questions one by one below:

    1. i have not discovered any new babies since the originals over 3 months ago. is it likely that they are continuing to breed, but that it was just a fluke that i happened to see them the one time before they became lost?

    Normally, a pregnant male will re-mate shortly after he delivers his latest brood, sometimes within an hour of ejecting the last of his young. In most cases, a mated pair of seahorses re-mates within 24-48 hours after the male gives birth.

    So if you have not seen any further indications of breeding, or discovered any more newborns, I suspect that’s because your seahorses have not mated again, rather than because the babies are disappearing or being predated before you notice the big event.

    Seahorses are most likely to give birth in the early morning hours shortly before or after sunrise, so if your not be an early riser, you may well have missed the spectacle of your male giving birth. For instance, this is how Carol Cozzi-Schmarr describes this phenomenon at the Ocean Rider aquaculture facility in Hawaii:

    " Male seahorses can give birth any time of day or night. Usually it depends on the photoperiod in your tank and when they are most comfortable. In my experience, I have seen that 90% of the time the male seahorse will give birth right at the crack of dawn. For example, in one section of our hatchery we have over 50 pairs of seahorses. On any given morning if you show up just before dawn, you will witness at least 5 males giving birth at exactly the same time which is right at dawn. It is spectacular!! So, I would bet that if you set your alarm to 1 hour before sunrise you just might get lucky!! But of course, you will have to ask Mr. seahorse to be sure!!!
    Aloha, Carol"

    But even if you missed the big moment, it would be very difficult to overlook the aftermath. A new brood of pelagic Hippocampus erectus fry is normally discovered immediately upon arising in the morning in the form of a writhing mass of newborn seahorses, hopelessly tangled together at the top of the tank.

    This dangerous situation develops because a newborn’s first instincts are to head to the surface to fill its air bladder and then to anchor itself to something solid. In the vastness of the ocean this is not a problem, since strong currents rapidly disperse the young, but in the confines of an aquarium, the first hitching post it finds will very likely be the tail or snout of one of its siblings. The same mistake is apt to be repeated by the rest of the pelagic fry, as they cluster at the surface, until the entire spawn is snarled together tail-to-tail, head-to-tail, tail-to-snout and so on. This is a very common experience when raising seahorses such as Hippocampus erectus, H. reidi, and H. ingens, which produce large broods of pelagic fry.

    In short, if your seahorses were actively breeding, I think you would have detected the signs of pregnancy in the males as their brood pouches expanded to accommodate the developing young, and it would be equally hard to miss the swarm of pelagic young at the surface of the aquarium afterwards.

    2. do you know how old the mustangs are typically when you guys sell them? how long do they usually live? when do they become full-sized? the babies i have now are not anywhere CLOSE to full grown.

    Mustangs and Sunbursts (Hippocampus erectus) are usually shipped around the age of 5-7 months, which is about when they begin to hit sexual maturity and pair off with one another. They are usually about 4 inches in total length at this age. Although most individuals are sexually mature when they are shipped, they normally don’t reach their maximum growth (6+ inches) until they are yearlings (i.e., between 1-2 years of age).

    In my experience, Mustangs and Sunbursts (Hippocampus erectus) have a life expectancy of 4-6 years in the home aquarium, if provided with good care. I have a pair of Mustangs in one of my home aquariums that are over five years in age, and I personally know of one old war horse raised by a colleague of mine that reached the ripe old age of 7 years and 3 months. At the Ocean Rider facility, I believe some of their original broodstock are older still, but of course the ideal conditions there are far different from the small,-closed-system aquaria and artificial saltwater we hobbyists must rely on.

    3. my tank is completely overgrown with plants. it looks pretty, keeps the algae under control, and the seahorses seem to love having all the places to hide and hitch onto. i’ve always thought plants were great for an aquarium, but can you have too much of a good thing?

    Seagrass meadows and algae beds are natural biotypes for seahorses, so a well-planted aquarium mimics their natural habitat for a well and often makes seahorses feel right at home. But there are a couple of circumstances under which an abundance of marine plants can become problematic in a small, close-system aquarium.

    The first of these is is a sudden die off of a bed of Caulerpa due to stress or sexual reproduction. This can be harmful because toxins may be released by the Caulerpa in the die off and the resulting decay of a considerable quantity of vegetable matter can degrade the water quality and reduce the level of dissolved oxygen in the tank due to a bacterial bloom. In severe cases, this combination of events can stress the other aquarium inhabitants or even wipe out the entire tank.

    For more information on this phenomenon, see Anthony Callo’s on the Best Plants and Algae for Refugia — Part II "Vegetable Filters," which is available online at the following URL:

    But if the aquarium is well circulated, well aerated, and well filtered, even one of these dreaded vegetative events or Caulerpa die offs is more of a nuisance than a threat to the aquarium inhabitants.

    As a case in point, consider the two-gallon tank I set up for photographic purposes when I did my first book on seahorses many years ago. This tank was lushly planted with an assortment of Caulerpa and other decorative macroalgae (Penicillus capitatus, Udotea, Halimeda sea cactus, etc.) and heavily stocked with a thriving colony of dwarf seahorses. Sure enough, right in the midst of a photo shoot, the Caulerpa chose that moment to die en masse, disintegrate and cloud the water. Much to my consternation, it turned the entire tank as opaque as a glass of milk in a matter of moments! At first visibility in the tank was perhaps an inch at best, but this gradually began to improve and after a period of several hours, the tank was crystal clear again. The primary source of filtration and aeration for that tiny tank was a simple, air-operated undergravel filter along with a considerable quantity of activated carbon, yet all of the dwarf seahorses survived the event with flying colors. In fact, one of the gravid males had given birth during the white out, and even the newborn fry were fine.

    If you’re growing Caulerpa in your seahorse tank, jfarmer, it can easily be prevented from going sexual and dying of simply by aggressively thinning out the colony. This is accomplished by regularly plucking out excess fronds of the fast-growing Caulerpa; when you subsequently you remove the excess Caulerpa you’ve plucked out of the main colony, you’re exporting phosphates, nitrates and other nutrients from the tank, thereby helping to maintain good water quality, and pruning the runners helps keep it from going sexual.

    When thinning out Caulerpa macroalgae, take care not to actually cut it. Remember, you’re not pruning hedges or trimming trees — the idea is to carefully pull up and remove continuous, unbroken fronds. Simply thin out the colony of excess strands, gently plucking up convenient fronds that can be readily removed intact. A little breakage is fine, but cutting or breaking too many strands will result in leaching undesirable substances into the aquarium water as the Caulerpa’s lifeblood drains away. Too much cutting or breaking can thus sap the colony’s strength and cause die offs or trigger the dreaded vegetative events that judicious thinning otherwise prevents.

    If you’re concerned about your ability to maintain and control of Caulerpa properly, just use a different forms of macroalgae that grows less rapidly instead and you can get the same sort of benefits at relatively little risk.

    The second situation in which a heavily planted aquarium can have an unintended impact on the marine aquarium is by altering the levels of oxygen and carbon dioxide in the aquarium as a result of photosynthesis. When the aquarium reflector is on, providing plenty of light, the algae and plants in the aquarium take in carbon dioxide and release oxygen as a byproduct of photosynthesis. As a result, the pH of the water and the dissolved oxygen levels rise throughout the day, while the level of dissolved carbon dioxide drops.

    Due to this process, you may notice tiny bubbles forming on your macroalgae and plants during the day. Those bubbles are the oxygen that the plants release when they are photosynthesizing. That’s perfectly normal and the only way it might present a problem would be if the macroalgae in your heavily planted tank were producing so much oxygen during the day that the aquarium water became supersaturated with it. That’s very unlikely and you can easily check whether oxygen supersaturation is occurring by using an oxygen test kit, as explained later in this message.

    On the other hand, during the night when the aquarium light is turned off and no photosynthesis takes place, the plants will begin to take in oxygen and give off carbon dioxide. This has exactly the opposite effect — the pH of the aquarium water and the level of dissolved oxygen drop at night, while the amount of dissolved carbon dioxide rises. This can occasionally become a problem in a small, poorly circulated, closed-system aquarium that is very heavily planted if the oxygen levels drop so much during the night and the carbon dioxide levels rise so high that the seahorses have difficulty breathing and getting enough oxygen.

    Seahorse setups are often more susceptible to such problems because hobbyists are so conscious of their seahorses’ limited swimming ability that they tend to leave their aquariums undercirculated. Poor circulation and inadequate surface agitation can lead to inefficient oxygenation and insufficient offgassing of carbon dioxide, aggravating the situation.

    Seahorses are more vulnerable to low O2/high CO2 levels than most fishes 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 unsually vulnernable to hypoxia when CO2 levels are high and/or O2 levels are low, and in extreme cases, they can be asphyxiated overnight.

    The daily fluctuations in pH, photosynthesis, dissolved oxygen/carbon dioxide, and redox levels that we have been discussing are natural and take place to a certain extent in all marine aquariums. Daily variances in chemical, physical and biological phenomena are a fact of life in aquaria, linked to the light and dark cycles and the diurnal rhythms of captive aquatic systems. As one example, the pH of aquarium water typically peaks after the lights have been on all day at a maximum of perhaps 8.4, only to drop to low of below 8.0 overnight. This is of course related to photosynthesis and the fact that zooanthellae and green plants consume CO2 and produce O2 when there is adequate light, but in essence reverse that process in the dark, consuming O2 and giving off CO2. Redox levels, available calcium and other water quality parameters are affected in similar ways. Ordinarily, these normal daily variations are not a cause for concern, but in a very heavily planted aquarium it’s possible, however unlikely, that they could result in oxygen supersaturation during the day or too little dissolved oxygen during the night to the detriment of your seahorses.

    You can easily check if your well planted seahorse tank is at any risk from these processes simply by checking the dissolved oxygen levels at the end of the day right before you turn off the aquarium for the night, at which time the oxygen levels should be at their highest, and then re-checking the dissolved oxygen levels first thing in the morning before you turn the aquarium lights on, which is when the dissolved oxygen levels should be their lowest. Compare and contrast these two readings to see how much of a difference there is in the dissolved oxygen levels during the day and overnight. Compare the readings to the optimal level of dissolved oxygen — if the dissolved oxygen level is off the chart during the day, there could be a danger of gas supersaturation; on the other hand, if the dissolved oxygen level is dropping far below the optimal range overnight, there could be a danger of asphyxiation, particularly during summertime heat waves (the warmer the water, the less dissolved oxygen it can hold).

    The Tetra Oxygen Test Kit (TetraTest 02) is a good liquid reagent test kit for fresh or saltwater with simple color scales for comparing readings that tests for 02 in the range of 2-14 PPM. It will cost you between $8.50 to $14 depending on where you shop and should be available at any well-stocked LFS. Salifert also makes a nice 02 Test Kit (their 02 Profi-Test) that will run you about $20.

    Either of those test kits fit the bill very well and are worthwhile investments for the seahorse keeper.

    Dissolved Oxygen (02): Optimum level = 6 – 7 ppm

    High levels of dissolved oxygen are vital to the well being of both fish and invertebrates. The key to maintaining high O2 levels in the aquarium is good circulation combined with surface agitation (Webber, 2004). Wet/dry trickle filters, bio-wheels, and protein skimmers facilitate efficient gas exchange and oxygenation. It is important for the hobbyist to monitor the dissolved oxygen levels in the aquarium because a drop in O2 levels is often an early indicator of impending trouble — a precursor of problems ahead. A drop in O2 levels will tip off the alert aquarist and allow corrective measures to be taken, nipping the problem in the bud before it adversely affects his seahorses. For example, a drop in O2 levels could be an early indicator of overcrowding — a signal that your system has reached its carrying capacity. Or it may merely signal a rise in the water temperature due to a summertime heat wave or indicate that the tank is overdue for a water change and/or a thorough cleaning to remove excess organics and accumulated detritus. Or it could be telling you that your tank is under circulated and you need to increase the surface agitation and water movement.

    The point is that checking the O2 levels in your aquarium can alert you to impending problems and allow you to do something about them before they have dire consequences. A drop in O2 levels is often the first sign of a water quality problem and it can tip off the alert aquarist that trouble is brewing before his seahorses are gasping for air in obvious respiratory distress. Checking the dissolved oxygen levels regularly is the next best thing to continuously monitoring the Oxidation-Reduction Potential (ORP) or redox of the water, which is a luxury few hobbyists can afford.

    As long as your dissolved oxygen levels are in the normal range at the end of the day and overnight, and there are no vegetative events during which the macroalgae dies off en masse, then you can be confident that your well planted aquarium isn’t creating any problems for your seahorses. Reducing the specific gravity in your aquarium to 1.015 will increase the amount of dissolved oxygen the water can hold, and therefore guard against both gas supersaturation and asphyxiation.

    Best of luck getting your seahorse system back to normal. Here’s hoping the two surviving three-month juveniles continue to grow and thrive.

    Pete Giwojna

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