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


Viewing 3 posts - 1 through 3 (of 3 total)
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  • #1736

    I have flatworm in my seahorse tank and I have been unsuccessful of getting rid of the ugly little critters! I’ve had 3 different blue velvets. They really do eat the worms but I can’t get them to stay alive more than 2 days! I’ve been doing water changes every other day and sucking out as many as I can, but they’re still on the glass. It’s been about 3 weeks now! I know there is flatworm exit but I’m scared to use it with my seahorses! Does anyone have any advice!?!?!?!?
    Thanks 🙁

    Pete Giwojna

    Dear Julie:

    I’m sorry to hear about your ongoing troubles with flatworms. But if the flatworms have become so numerous that they are problematic, and controlling them biologically with blue velvet nudibranchs has not been successful, then the Flatworm Exit is probably your best alternative. I know you are concerned about the effect the toxins released from the dead flatworms could have on your seahorses, so this is what I would recommend, Julie:

    (1) First obtain some fresh activated carbon and a Polyfilter Pad (from Poly-Bio Marine) that you can add to the external filter for your seahorse tank after you have treated with the Flatworm Exit. The activated carbon and Polyfilter Pad will remove any toxins or contaminants from the aquarium water following the treatment, so the seahorses won’t be affected.

    (2) Remove the seahorses and any other delicate specimens such as cleaner shrimp or starfish to your hospital tank before you treat the main tank with the Flatworm Exit. If you do not have a hospital tank or quarantine tank set up, a clean 5-gallon plastic bucket (new and unused, NOT an old scrub bucket!) can serve as a makeshift hospital tank. It should be aerated and equipped with hitching posts and perhaps a heater, but nothing else. That will make it safe home for the seahorses and other sensitive specimens temporarily while you treat the main tank with the Flatworm Exit.

    (3) Siphon out as many of the flatworms from the glass and other areas of the aquarium as possible, just as you have been doing so diligently all along, Julie, and then administer the Flatworm Exit to your main tank according to the instructions.

    (4) After the Flatworm Exit has done its job and destroyed the flatworms, perform a major water change on your main tank and then install the fresh activated carbon and the Polyfilter Pad that you obtained previously in the hang-on-the-back filter or canister filter on your seahorse tank so they can remove any remaining toxins or contaminants.

    (5) Filter the water in your main tank through the activated carbon and Polyfilter Pad for 24 hours to remove any residual harmful substances from the aquarium water, and then test all your water quality parameters (ammonia, nitrite, nitrate, pH, and salinity or specific gravity) to make sure the readings are as they should be.

    (6) If everything tests out properly, as it should, go ahead and return the seahorses from the hospital tank to your main tank, but make sure you have some additional freshly mixed saltwater ready to go in case another water change seems advisable.

    Following these steps should allow you to treat your seahorse tank with the Flatworm Exit and destroy the flatworms without any danger to your seahorses, Julie. But before you do anything else, please read through the following information, which is what I normally advise seahorse keepers regarding flatworms:

    <Open quote>
    Flatworms and Seahorses

    There are a few parasitic flatworms that plague seahorses, such as tapeworms (Cestodes) and blood-sucking flukes or trematodes, which are like tiny leeches, but these require a host to survive. Most of these flatworms that find their way into our aquariums are free-living (nonparasitic), and the vast majority of these are benign, harmless creatures that are often best ignored, although they can be troublesome when their population gets out of control. If you have the noxious kind of flatworms, or a population explosion and they are crawling on your seahorses and causing irritation, they should be eliminated, but by and large flatworms are more of a danger to live corals/clams and the reef keeper than a danger to seahorses. They can actually cause more harm when they are dead than when they are alive, because their decaying bodies can release toxic substances in the water when they die en masse.

    The first step in eliminating the flatworms is to siphon out as many of them as possible so that the remainder can be eradicated safely. One possibility is to use a blue velvet nudibranch to limit the flatworm population naturally as a means of biological control. That species feeds naturally on flatworms of the type that often appear in reef tanks.

    If you can possibly obtain a blue velvet nudibranch, there would be no harm in putting it in your seahorse tank in order to see if will feed on your particular flatworms and eliminate them naturally. That would be preferable to eradicating them chemically, which is the other alternative we will discuss at the end of this letter. But it can be difficult to obtain a blue velvet nudibranch, or if you are able to get one, it may not feed on the particular type of flatworms that are in your tank. That would certainly be worth a try, though…

    In the meantime, here is a link to a good article on flatworms by Bob Fenner, which is loaded with good information and a number of pictures, and may help you to determine if your flatworms might present a risk to your seahorses:

    Click here: Flatworms

    If you want to be absolutely safe, you can certainly eradicate the flatworms from your tank. Flatworms are more of a risk to reef keepers because some species attack clams and certain types of corals, and reefers swear by a product made by Salifert called Flatworm Exit. It wipes out flatworms but is said to be completely harmless to other invertebrates and fish when used as directed:

    Flatworm eXit itself is quite safe to fish and invertebrates. However, the body fluids of flatworms can be toxic to some reef inhabitants when present in a too high concentration. This body fluid is sometimes excreted when flatworms die. When you use this product it is important to do the following first:

    *Siphon out as many flatworms as possible.
    *Keep sufficient fresh activated carbon in a canister ready.
    *Turn off UV, ozone and remove activated carbon before treating the tank.
    *Keep the skimmer turned on.

    Important Remarks:

    The following remarks are meant to reduce the amount of the flatworm’s toxic body fluids in the water.

    Many people have treated their reef tank(s) successfully using Flatworm eXit without any problems. The most important factors are reducing the number of flatworms before commencing with the treatment and reducing the amount of the flatworm’s body fluids, released when they die, as fast as possible.

    Do not underestimate the number of flatworms in your system. In a few cases a significant number of flatworms can be hiding in for example crevices. Blow in such and any other potential hiding places water to blow any flatworm out of there. For that purpose you can use a powerhead or a turkey baster. Siphon out those flatworms as well.

    Do not underestimate the amount of toxic body fluids these flatworms can excrete. This can be reduced significantly by really siphoning out the flatworms before commencing with the treatment. Further significant reduction is accomplished by siphoning out as many dead flatworms as you can. Any body fluids released by the dead flatworms in the water has to be reduced further by using about 1 pound of fresh high quality carbon for every 50 gallons. The carbon has to be used in a canister with a sufficient forced water flow.

    Take sufficient time for treating the tank. That is, do not treat your tank in a hurry. Also take time to monitor your tank for at least 6 hours after the treatment. It is also wise to have at least 25% water ready for a water change if required.

    Flatworm Exit is available online from a number of different sources. I have never used this particular product, so I cannot vouch for it or say for certain that it’s safe with seahorses, but if it’s used in reef tanks and doesn’t harm the delicate corals and invertebrates, it’s very unlikely it could be harmful to seahorses when used as directed. And if you remove the seahorses while the main tank is being treated, and then filter the aquarium water through fresh activated carbon and a Polyfilter Pad afterwards, there would be no danger to your ponies…

    If you find the flatworms unsightly, or feel they may present a health risk to your seahorses, go ahead and eliminate them. Just observe the safety precautions outlined above.
    <Close quote>

    Best of luck getting rid of your flatworms, Julie! They most likely found their way into your aquarium has hitchhikers on a piece of live rock or live coral, or perhaps amidst some macroalgae.

    Pete Giwojna

    Pete Giwojna

    Dear Julie:

    Here is a copy of an e-mail I recently sent to another hobbyist who is having a problem with flatworms and does not want to eliminate them using chemical means. It discusses biological control of the flatworms in more detail, and also explains how they can be controlled using hyposalinity, in addition to providing an article on controlling flatworms by Anthony Calfo. Hopefully you will find the additional information to be useful as well:

    Dear Omar:

    Yes, sir, if your aquarium is large enough, a small six-line wrasse (Pseudocheilinus hexataenia) can make a good companion for seahorses, providing you are willing to target feed the seahorses at mealtime to make sure that they get their fair share to eat. The six-line wrasse should not be aggressive towards the seahorses, but it will compete with them for the frozen Mysis and is an active, agile swimmer that can easily outcompete the ponies unless the aquarist intervenes, as discussed below:

    Feeding Seahorses in a Community Tank

    When keeping seahorses in an appropriately elaborate environment, it is imperative that you feed them properly! Domesticated seahorses thrive on enriched frozen Mysis as their staple, everyday diet. But the worst thing you can do when feeding the seahorses in a intricate reef or live rock environment is to scatter a handful of frozen Mysis throughout the tank to be dispersed by the currents and hope that the hungry horses can track it all down. Inevitably some of the frozen food will be swept away and lodge in isolated nooks and crannies where the seahorses cannot get it (Giwojna, 2005). There it will begin to decompose and degrade the water quality, which is why ammonia spikes are common after a heavy feeding. Or it may be wafted out into the open again later on and eaten after it has begun to spoil. Either outcome can have dire consequences (Giwojna, 2005).

    The best way to avoid such problems is to target feed your seahorses or set up a feeding station for them. See my online article in Conscientious Aquarist for a detailed discussion explaining exactly how to set up a feeding station and train your seahorses to use it:

    Click here: Seahorse Feeders

    Personally, I prefer to target feed my seahorses instead. The individual personalities of seahorses naturally extend to their feeding habits. Some are aggressive feeders that will boldly snatch food from your fingers, while some are shy and secretive, feeding only when they think they’re not being observed. Some like to slurp up Mysis while it’s swirling through the water column, and some will only take Mysis off the bottom of the tank. Some are voracious pigs that greedily scarf up everything in sight, and some are slow, deliberate feeders that painstakingly examine every morsel of Mysis before they accept or reject it. Some eat like horses and some eat like birds. So how does the seahorse keeper make sure all his charges are getting enough to eat at mealtime? How does the hobbyist keep the aggressive eaters from gobbling up all the mouth-watering Mysis before the slower feeders get their fair share? And how can you keep active fishes and inverts with seahorses without the faster fishes gobbling up all the goodies before the slowpoke seahorses can grab a mouthful (Giwojna, unpublished)?

    Target feeding is the answer. Target feeding just means offering a single piece of Mysis to one particular seahorse, and then watching to see whether or not the ‘horse you targeted actually eats the shrimp. Feeding each of your seahorses in turn that way makes it easy to keep track of exactly how much each of your specimens is eating (Giwojna, unpublished).

    There are many different ways to target feed seahorses. Most methods involve using a long utensil of some sort to wave the Mysis temptingly in front of the chosen seahorse; once you’re sure this has attracted his interest, the Mysis is released so it drifts down enticingly right before the seahorse’s snout. Most of the time, the seahorse will snatch it up as it drifts by or snap it up as soon as it hits the bottom (Giwojna, unpublished).

    A great number of utensils work well for target feeding. I’ve seen hobbyists use everything from chopsticks to extra long tweezers and hemostats or forceps to homemade pipettes fashioned from a length of rigid plastic tubing. As for myself, I prefer handfeeding when I target feed a particular seahorse (Giwojna, unpublished).

    But no doubt the all-time favorite implement for target feeding seahorses is the old-fashioned turkey baster. The old-fashioned ones with the glass barrels work best because the seahorses can see the Mysis inside the baster all the way as it moves down the barrel and out the tip. By exerting just the right amount of pressure on the bulb, great precision is possible when target feeding with a turkey baster. By squeezing and releasing the bulb ever so slightly, a skillful target feeder can keep a piece of Mysis dancing at the very tip of the baster indefinitely, and hold the tempting morsel right in front of the seahorse’s mouth as long as necessary. Or if the seahorse rejects the Mysis the first time it drifts by, a baster makes it easy to deftly suck up the shrimp from the bottom so it can be offered to the target again. In the same way, the baster makes it a simple matter to clean any remaining leftovers after a feeding session (Giwojna, unpublished). (You’ll quickly discover the feeding tube is also indispensable for tapping away pesky fish and invertebrates that threaten to steal the tempting tidbit before an indecisive seahorse can snatch it up.)

    In short, target feeding allows the hobbyist to assure that each of his seahorses gets enough to eat without overfeeding or underfeeding the tank. And it makes it possible to keep seahorses in a community tank with more active fishes that would ordinarily out-compete them for food, since the aquarist can personally deliver each mouthful to the seahorses while keeping more aggressive specimens at bay (Giwojna, unpublished).

    The key to keeping active specimens like firefish and occelaris clownfish or cleaner shrimp successfully with seahorses is to feed the other fish and inverts with standard, off-the-shelf aquarium foods first, and once they’ve had their fill, then target feed the seahorses

    Unfortunately, Omar, there are no easy solutions for ridding a marine aquarium from flatworms (i.e., planaria) once they become established in the tank. If you do not want to use chemicals or medications to eliminate the flatworm population, your best options are to try biological control in conjunction with good aquarium management (eliminating excess nutrients, operating an efficient protein skimmer 24 hours a day, maintain good water circulation to eliminate dead spots, etc.) or to try treating the aquarium with low salinity, providing it is not housing any delicate invertebrates. For biological control, the blue velvet nudibranch and certain types of wrasse (including the six-line wrasse) will sometimes feed on the flatworms and can help keep their numbers under control. Otherwise, treating the aquarium with hyposalinity will also kill off the flatworms. Here is a good article by Anthony Calfo that discusses flatworms and how to deal with them in more detail, Omar:

    <Cheers, Martha. Anthony Calfo in your service>
    I need some advice about ridding my tank of a red flatworm invasion.
    <a common problem>
    I have a 75 gallon reef. 5" DSB with 110lbs of live rock. I have LPS only and 1400gph for circulation being moved about by two sea swirls, giving the tank quite turbulent waters, IMO.
    <but are the worms mostly in the lesser current areas? They do hate strong water flow>
    I have a 20 gallon refugium and use an AquaC EV180 skimmer.
    Ammonia & Nitrites 0, nitrates 10ppm, ph 8.4 (average) SG 1.024, temp 81 degrees. I have a calcium reactor
    that keeps a consistent reading of Ca 440, and Alk 11dkh.
    <all outstanding>
    This flatworm population has taken over my tank. It is all over the live rocks, on the sand bed and has attached to my two candy canes and open brains. It is really starting to worry me.
    <no reflection of tank health or husbandry… just one of those things>
    At first it was just an eye sore, but now it seems to be out of hand.
    Is there any known way of ridding a tank of these creatures, or are they here to stay?
    <no…in fact, they often wax (hard) and wane (suddenly) on their own.>
    If you have any information on these pests I would love to read about it. Thanks for your time. Martha
    P.S. I have enclosed two pictures of these flatworms
    <no easy solution Martha… aggressive skimming, very strong water flow, perhaps a natural predator (if tankmates allow) and time usually take care of the matter… even if it takes a couple of months. The following is an excerpt from my Book of Coral Propagation, Vol. 1 on these so-called "Rust-Brown Planaria":

    "Rust Brown Planarians are just one such example of a nuisance organism that needs to be monitored if not controlled. This flatworm is usually 1/8 to ?” in size (~3-6mm) with a color ranging from orange through red to brown. It is cited in aquarium literature as Convolutriloba retrogemma and considered to be a pest because it can expand in population to plague proportions in a matter of a few short months. Populations get so dense that they occur in crowded mats that literally block necessary sunlight and circulatory functions from the corals that are forced to serve as perches for them. They are said to ingest zooxanthellae from decaying coral tissue and prosper under bright illumination. They dislike strong water flow and are often noticed in the areas of weakest water movement in an infected display. Increased water movement alone in otherwise properly maintained aquariums can sometimes reduce the population of flatworms.

    Aggressive protein skimming also helps to control the population of this annoying pest. It has also been demonstrated that low salinity impedes the growth of flatworm populations but at the expense of other desirable invertebrates in the display if applied as a long bath. I once inadvertently dropped the salinity of a badly infected system from 1.023 to 1.017 with a water exchange using water that I thought was salted… but was not. The sharp drop in salinity promptly killed every discernible flatworm in the display, but shocked every Sinularia into expelling zooxanthellae at the same time! The leather corals took months to recover and I would never recommend imposing such shock deliberately. Indeed, short freshwater baths are effective against many Planaria, but quite stressful to other desirable coral and invertebrates even on selectively treated rocks.

    Natural predation may help but is somewhat unpredictable. Dragonets (Synchiropus species) and Leopard wrasses (Macropharyngodon species) have been used with varying degrees of success. Both fishes are truly in need of care by advanced aquarists. Leopard wrasses and dragonets will survive very well in systems with refugiums generating copious amounts of zooplankton as well. Chelidonura species of sea slugs have also been cited as excellent natural predators, but acquiring an effective species is difficult for many livestock resellers, as collectors often lump various Nudibranchs into an assorted category. The result is that numerous species of sea slugs unsuitable for captivity get imported in an effort to acquire just one that eats this species of flatworm.
    <Close quote>

    Okay, Omar, that’s what Anthony Calfo advices regarding flatworms. As you can see, they are difficult to control and eliminate from an aquarium once and for all without resorting to chemical means. Biological control or natural predation is worth a try but often produces uncertain results and can only help to keep the numbers of flatworms down, rather than eliminating them.

    The following website has more good information on controlling flatworms and is also worth reading before you decide which option you would like to try for ridding your tank of the flatworms, Omar. Just copy the following URL, paste it in your Web browser, and press the "Enter" key, and it will take you directly to the article:

    If you do not have a lot of sensitive invertebrates in the aquarium, then treating the tank with hyposalinity may be your best option for eradicating the flatworms, Omar. The following information will explain how to administer hyposalinity safely, sir, but as we discussed on the forum with regard to Flatworm Exit, the massive die off of the entire flatworm population can in itself be problematic. So if you treat the tank with hyposalinity, be sure to follow up the treatment with the measures we discussed in the forum to remove the noxious substances and toxic chemicals released by the dead flatworms, such as the use of fresh activated carbon, a Polyfilter Pad (by Poly-Bio Marine), heavy protein skimming throughout, siphoning out as many of the flatworms as possible beforehand, and performing a major water change afterwards. Here are the instructions for administering hyposalinity, Omar:

    Hyposalinity or Osmotic Shock Therapy (OST)

    Fortunately, when problems with protozoan parasites and ectoparasites crop up, we needn’t determine which particular parasite is plaguing our seahorses, since hyposalinity or Osmotic Shock Therapy (OST) is a very safe treatment that is effective against protozoans and ectoparasites in general. OST is totally noninvasive and harmless to seahorses and most other fishes, can be administered safely in the display tank rather than a hospital tank to eradicate the protozoan parasites from your system, and is completely compatible with UV and any medications you may be using (Giwojna, Dec. 2003). OST is therefore the treatment I recommend for problems with external parasites other than Uronema.

    Hyposalinity also helps parasite-ridden fish avoid dehydration and save their strength by reducing osmotic pressure and making it easier for them to osmoregulate. Allow me to explain.

    Because the seawater they live in is far saltier than their blood and internal body fluids (Kollman, 1998), marine fish are constantly losing water by diffusion through their gills and the surface of their skin, as well as in their urine (Kollman, 1998). The mucus layer or slime coat of the fish helps waterproof the skin and reduces the amount of water that can diffuse through its surface (Kollman, 1998). However, when the skin is attacked by parasites such as Costia, Cryptocaryon, Cryptobia, Amyloodinium, Brooklynella, Epistylus and the like, this protective barrier is damaged and water is lost at an increasing rate (Kollman, 1998). The affected fish can easily become dehydrated as a result, further debilitating them.

    Low salinity is an excellent way to treat most such skin infections, since reducing the salinity helps the fish recover in several different ways. It lessens the risk of dehydration by decreasing osmotic pressure (Kollman, 1998), and reduces the amount of energy the fish must expend on osmoregulation, helping the weakened fish to recover (Kollman, 1998).

    And if the salinity is dropped far enough, it prevents reinfection and provides the fish with immediate relief by destroying the parasites in the water and on the surface of the skin (Kollman, 1998). At low salinity, water moves into the parasites’ bodies by passive diffusion until they literally burst (lyse). This method of treatment is known as hyposalinity or Osmotic Shock Therapy.

    At the first sign of parasitic infection, I therefore suggest instituting a two-pronged treatment regimen immediately: (1) first, administer a freshwater dip to your seahorses to reduce the number of embedded parasites, clear the gills and snout as much as possible, and provide the seahorses with some quick relief, and (2) treat your main tank with osmotic shock therapy, dropping the salinity to 15 ppt (1.011-1.012) for several weeks to eliminate the parasites from your system entirely (Giwojna, Dec. 2003). If your seahorses seem too weak to handle the stress of a freshwater dip, then just get them into hyposalinity water ASAP — no acclimation!

    Step 1: Freshwater Dip

    A freshwater dip is simply immersing your seahorse in pure, detoxified freshwater that’s been preadjusted to the same temp and pH as the water the seahorse is accustomed to, for a period of at least 10 minutes (Giwojna, Dec. 2003). It doesn’t harm them — seahorses typically tolerate freshwater dips exceptionally well and a 10-minute dip should be perfectly safe. Freshwater dips are effective because marine fish tolerate the immersion in freshwater far better than the external parasites they play host to; the change in osmotic pressure kills or incapacitates such microorganisms within 7-8 minutes (Giwojna, Dec. 2003). A minimum dip, if the fish seems to be doing fine, is therefore 8 minutes. Include some sort of hitching post in the dipping container and shoot for the full 10 minutes with your seahorses (Giwojna, Dec. 2003).

    If you will be using tap water for the freshwater dip, be sure to dechlorinate it beforehand. This can be accomplished usually one of the commercial dechlorinators, which typically include sodium thiosulfate and perhaps a chloramine remover as well, or by aerating the tap water for at least 24 hours to dissipate the chlorine (Giwojna, Dec. 2003).

    If you dechlorinate the dip water with a sodium thiosulfate product, be sure to use an airstone to aerate it for at least one hour before administering the dip. This is because the sodium thiosulfate depletes the water of oxygen and the dip water must therefore be oxygenated before its suitable for your seahorse(s). Regardless of how you detoxify the freshwater for the dip, it’s important to aerate the water in the dipping container well beforehand to increase the level of dissolved oxygen in the water. Many hobbyists leave the airstone in the dipping container throughout the procedure.

    Adjusting the pH of the water in the dipping container so that it matches the pH of the water in the aquarium is a crucial step. Ordinary baking soda (sodium bicarbonate) will suffice for raising the pH of the water. If there is too much of a difference in the pH, there is a possibility the seahorse could go into shock during the dipping procedure. Preadjusting the pH will prevent that from happening. If you will are unsure about your ability to accurately adjust the pH in the dipping container, avoid this procedure altogether or be prepared to monitor the seahorse very carefully or shorten the duration of the tip to no more than about 4 minutes.

    Observe the horse closely during the dip. You may see some immediate signs of distress or shock. Sometimes the horse will immediately lie on its side on the bottom. That’s a fairly common reaction — normal and to be expected, rather than a cause for concern, so don’t be alarmed if this happens. Just nudge or tap the seahorse gently with your finger if it lies down on its side. Normally, the seahorse will respond to the slight nudge by righting itself again and calm down for the duration of the dip. However, if it does not respond, stop the treatment.

    Most seahorses tolerate the treatment well and experience no problems, but if you see continued signs of distress — twitching, thrashing around etc. — stop the treatment.

    After you have completed the dip and returned the seahorses to the aquarium, save the dip water and examine it closely for any sign of parasites. The change in osmotic pressure from saltwater to freshwater will cause ectoparasites to lyse (i.e., swell and burst) or drop off their host after 7-10 minutes, and they will be left behind in the dipping water. Protozoan parasites are microscopic and won’t be visible to the naked eye, but some of the other ectoparasites can be clearly seen. For example, monogenetic trematodes will appear as opaque sesame seeds drifting in the water (Giwojna, Aug. 2003) and some nematodes may be visible as tiny hairlike worms 1/16-3/16 of an inch long. Other parasites may appear as tiny dots in the water. Freshwater dips can thus often provide affected seahorses with some immediate relief by ridding them of these irritating pests and can also aid their breathing by flushing out gill parasites.

    Step 2: Hyposalinity (Osmotic Shock Therapy)

    Osmotic Shock Therapy (OST) involves maintaining the saltwater in your system at a much lower specific gravity than normal: 1.017 is recommended for reef tanks with live coral and invertebrates, while 1.011 (15 ppt salinity) is appropriate for fish-only tanks (Giwojna, Dec. 2003). Essentially, OST simply places the infectious organisms in an environment in which they cannot hope to survive while the host (or infected fish) is unaffected (Hauter, 2004). It is therefore the parasites that are subjected to the shock, not the fishes, which are normally quite content at the prescribed salinities (Giwojna, Dec. 2003). This low salinity method can be thought of as a continuous freshwater dip, and provides basically the same benefits as a 5-10 minute freshwater dip does, only long term (Giwojna, Dec. 2003).

    When the salinity in the system is lowered initially, 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 (1.010-1.012) over a period of several hours is fine (Don Carner, pers. com.). The bacteria colony in the biofilter will survive, the fish will survive, but the parasites will not (Don Carner, pers. com.).

    By lowering the salinity, we are also lowering the osmotic pressure of the water. The parasites NEED high osmotic pressure externally in order to maintain a normal water balance within their bodies (Don Carner, pers. com.). Reduce the salinity of the surrounding saltwater sufficiently, and water moves via osmosis into the parasites’ bodies until they literally explode (Giwojna, Dec. 2003). As a higher life form, the fish can withstand this treatment very well; invertebrates and parasites cannot (Don Carner, pers. com.).

    For best results, I recommend removing your seahorses to a hospital tank or bucket filled with full strength saltwater (1.022-1.025) while dropping the salinity in the main tank. They can be given their freshwater dips while you are reducing the salinity in the main tank. Once the specific gravity in the display tank has been lowered to the desired level, the seahorses can then be released directly into the main tank without any acclimation whatsoever. They will make the transition from full strength saltwater to hyposalinity wonderful well, without missing a beat, whereas the ectoparasites they are carrying will be subjected to a lethal change in osmotic pressure.

    Do not hesitate to maintain the hyposalinity for the entire treatment period. OST needs to maintained for at least 3 weeks in order to assure that all of the encysted parasites have reached the free-swimming stage of their life cycle and been killed.

    CAUTION! When administering hyposalinity to seahorses, be very careful as you add the freshwater when you approach the target salinity. You do NOT want to overshoot the mark and drop the salinity too far! Seahorses tolerate low salinity very well up to a certain point, but they cannot withstand salinities below 13.3 ppt (specific gravity = 1.010) indefinitely. Salinities below 1.010 may be fatal to seahorses in a matter of days, if not hours.

    In the olden days, many attempts were made to gradually convert seahorses from saltwater to freshwater. Hippocampus erectus tolerated these experiments splendidly all the way down to specific gravity of 1.010, but when the salinity was dropped any further, the seahorses all perished (Bellomy, 1969, p7). These experiments were repeated with several groups of seahorses representing different subspecies of erectus, and the results were always the same: fine as low as 1.010 — defunct at 1.009 (Bellomy, 1969, p7)!

    Keeping that in mind, it is best to make your target salinity 1.011-1.012 to allow a margin for error, and to transfer your seahorses to a hospital tank while you drop the salinity in the main tank. That way no harm will be done if you accidentally take the salinity down too far in your main tank before readjusting it and hitting your target salinity. And when you return the seahorses from normal salinity in the hospital tank to the main tank at 1.011-1.012, the parasites will be subjected to the greatest possible osmotic shock, leaving them no chance at all to adjust to change in osmotic pressure.

    To be safe and effective, administering hyposalinity requires the use of an accurate method for measuring salinity/specific gravity such as a refractometer. If you will be relying on a pet-store hydrometer for your readings, you may wish to consider alternate treatments rather than OST. If you do decide to try hyposalinity using a hydrometer, please observe the following precautions:

    Be aware of the temperature at which your hydrometer was calibrated and make full use of conversion charts to adjust your readings based on the actual temperature of the water aquarium water.

    Make your target salinity 20 ppt (specific gravity = 1.015) to allow for a greater margin for error.

    In addition, when administering OST it is important to monitor your ammonia and nitrite levels closely at first. Hyposalinity may temporarily impact the nitrifying bacteria in your biofilter, so check your readings closely to see if there is a spike once you’ve reached your target salinity. If so, a simple water change will correct the problem and your biofiltration will be back to normal shortly.

    The hobbyist should also bear in mind that hyposalinity can delay gonadal development in immature seahorses and may also prevent mature seahorses from breeding until the salinity is returned to normal. So don’t maintain low salinity for the long term — as soon as the 3-4 week treatment period is over, bring the specific gravity in the main tank back up 1.024-1.025.

    When you are ready to return the system to normal salinity, simply reverse the process, remove some of the low salinity water in the aquarium and replace it with high salinity water. Take your time and raise the salinity slowly and gradually. Fish can become dehydrated if the salinity is increased too rapidly, so be methodical and raise the salinity over a period of several days. Don’t hesitate to take a full week to return the specific gravity to normal levels again in small increments.

    If your tank contains corals or delicate invertebrates, or you just want to be extra cautious with your seahorses as they recuperate, adjust the salinity more slowly. This can be accomplished by making smaller water changes, which will require more steps to raise the salinity back to normal, or by reducing the specific gravity of the high-salinity replacement water somewhat. Make the adjustment back to normal salinity as gradually as necessary in order to be confident that you are not stressing the specimens. The hyposalinity should already have done its job so you can afford to be cautious when readjusting the salinity. Take all the time you want.

    To be absolutely certain that things go smoothly, take advantage of the online Salinity Adjustment Calculator at the following web site:

    This calculator takes the amount of water in your system, your current salinity, the salinity you’d like to achieve, and the maximum change in salinity that you are willing to risk per water change into consideration and performs the necessary calculations. It then returns the number of gallons and salinity of the water for each change (Taylor, 2001b).

    The low salinity system was initially developed at the Instant Ocean Hatcheries in the 1980’s and has since been perfected by other large-scale operations (Giwojna, Dec. 2003). Thomas Frakes at Aquarium Systems recommends this system and Rand Kollman recently conducted a controlled study of the method, as described below (Kollman, 1998):

    During the study, fourteen 40-gallon tanks connected to a common filtration system at Kollman’s dealership were run at 15 ppt salinity (specific gravity = 1.011), while sixteen other 30-gallon tanks, connected to their own separate filtration system, were maintained at normal salinities of 27-30 ppt (specific gravity = 1.020-1.022) and served as the control group for the experiment (Kollman, 1998; Giwojna, Dec. 2003). Both systems had identical filtration and were maintained at the same temperature (between 79-80 degrees F), Kollman, 1998.

    The test period ran continuously from 1994 to 1997, during which time marine fish from the Red Sea, Caribbean and throughout the Indo-Pacific were maintained in both systems (Kollman, 1998). Whenever fish arrived from wholesalers or transshipments, they were divided evenly between the low salinity and the normal salinity (control) system with no acclimation procedures whatsoever (Kollman, 1998; Giwojna, Dec. 2003). No differences in behavior were observed between the fishes in the two systems during the trial period (Giwojna, Dec. 2003).

    The results of the three-year study were dramatic and conclusive (Giwojna, Dec. 2003). Outbreaks of Amyloodinium, Cryptocaryon, turbellarians, and monogenetic trematodes were simply not seen in the low salinity system, and periodic microscopic examinations of skin scrapings and gill clippings confirmed that none of the parasites were present (Kollman, 1998; Giwojna, Dec. 2003). On the other hand, the normal salinity control system continued to have periodic outbreaks of all the above parasites. Furthermore, infected fish from the control system were cleared of their parasites within a few days if transferred to the low salinity system (Kollman, 1998; Giwojna, Dec. 2003).

    Kollman found the low salinity system reduced his previously high mortality rates and that his dealership was able to greatly reduce chemical treatments and subsequent overdoses (Kollman, 1998; Giwojna, Dec. 2003). He concluded that a salinity of 14 to 15 ppt (specific gravity = 1.010-1.011) was an effective treatment level to which fish can be immediately transferred with no special acclimation procedures (Kollman, 1998; Giwojna, Dec. 2003). Although the rapid turnover of specimens at his dealership prevented him from reaching any definitive conclusions about the long-term effects of low salinity on marine fishes, Kollman noted that several fish were maintained in the system for well over a year with no ill effects, and that a Red Sea angelfish (Pomacanthus maculosus) thrived in the low salinity system for three-and-a-half years (Kollman, 1998; Giwojna, Dec. 2003)!

    Kollman’s study and the ongoing program at Instant Ocean hatcheries are not the only reports on utilizing low salinity water to quarantine specimens held under crowded conditions (Giwojna, Dec. 2003). As early as 1985, Colorni published a study in Diseases of Aquatic Organism on the effectiveness of hyposalinity in controlling Cryptocaryon irritans in cultured sea bream (Colorni, 1985). Randolph Goodlett and Lance Ichinotsubo have likewise reported their own low-salinity treatment techniques, recommending at least 3 weeks exposure at 14 ppt (specific gravity = 1.010) for a broad range of marine tropical fish species to control various parasites (Goodlett and Ichinotsubo, 1997). They too reported that fish handled immediate transfer into low salinity water "beautifully (Goodlett and Ichinotsubo, 1997)." Variations of low salinity or OST are also gaining popularity among reefkeepers for curing disease outbreaks in reef tanks where copper and other medications cannot be used (Frakes, 1994; Giwojna, Dec. 2003).

    Low Salinity Pros (Giwojna, Dec. 2003):

    1. Less stressful and longer lasting than freshwater dipping.
    2. More effective than freshwater dipping outside the aquaria, since OST kills the free swimming parasites as they emerge from dormant cysts/spores within the aquaria/system as well as those attached to the fish (i.e., the fish are not reinfected once they are returned from the bath to the main tank).
    3. No special acclimation procedures required for newcomers.
    4. Suitable for all marine teleost (bony) fishes (Red Sea, Indo-Pacific, Florida & Caribbean).
    5. Seahorses tolerate hyposalinity extremely well.
    6. Eliminates outbreaks of Cryptocaryon irritans (White Spot Disease/Marine Ick).
    7. Eliminates turbellarians (Black Spot/Clownfish Disease).
    8. Eliminates most ectoparasites, including trematodes, flukes, leeches and Argulus;
    9. Prevents the spread of protozoal parasites in general.
    10. Reduces the risk of dehydration when the integrity of the fish’ slime coat is disrupted;
    11. Helps weakened fish conserve energy and husband their strength by lowering osmotic pressure and making it easier for them to osmoregulate.
    12. Reduces dependency on chemical treatments such as copper and formalin.
    13. Eliminates the risk of overdoses.
    14. Proven to improve the health of marine teleost fishes kept in crowded containment systems with a heavy biological load.
    15. Can be used safely with protein, skimmers, ozone, UV, and other treatments.
    16. Increases the levels of dissolved oxygen in the aquarium.
    17. Helps prevent gas supersaturation, minimizing problems with gas bubble syndrome.

    Low Salinity Cons (Giwojna, Dec. 2003):

    1. Sharks and rays are unable to adjust to low salinity systems or tolerate OST.
    2. Cannot be used with corals and invertebrates at salinities recommended for fishes.
    3. Can be harmful to seahorses at salinities below 13.3 ppt (specific gravity = 1.010).
    4. May delay gonadal development in seahorses and prevent breeding until the salinity is returned to normal.
    5. Requires an accurate method for measuring salinity/specific gravity such as a refractometer for best results.
    6. May not be helpful in cases of Uronema — the most common protozoan parasite infection in seahorses.
    7. May impact nitrifying bacteria in the biofilter temporarily.
    8. Not recommended for long-term maintenance (this will not be a concern for any fishes that are in the system for 6-8 weeks or less).
    9. Results vary — many hobbyists report great success with hyposalinity; others have no luck using this technique. Much depends on how OST was administered, how low the salinity was reduced and how quickly it was dropped, the accuracy of the salinity measurements, the particular parasite(s) involved and how early treatment was begun.

    Invertebrates differ in their tolerance for hyposalinity. Kollman notes that he was able to keep several crustaceans at a fairly low salinity of 18-19 ppt (specific gravity = 1.013 to 1.014). These included arrow crabs, peppermint shrimp, and emerald crabs (Kollman, 1998). Hermit crabs are generally perfectly happy undergoing OST, echinoderms (starfish and urchins) typically don’t tolerate it at all, most shrimp are sensitive, snails vary (Giwojna, Dec. 2003). Nerites and periwinkles don’t mind it at all, others are okay at 1.017 but you can kiss them goodbye at 1.010. Most corals are vulnerable to full OST (Giwojna, Dec. 2003). Reefkeepers and hobbyists with sensitive animals usually do a modified version of OST where they lower the salinity to 1.017 rather than 1.010 (Giwojna, Dec. 2003). The delicate animals generally tolerate 1.017 well and although that’s not as effective in eradicating parasites, a specific gravity of 1.017 is still low enough to provide many of the benefits of hyposalinity (Giwojna, Dec. 2003).

    For a standard SHOWLR setup with a clean-up consisting of assorted snails, microhermits, and cleaner shrimp, I recommend relocating the snails and shrimp while treating your seahorse system with full OST at a specific 1.011-1.012 for several weeks. If that’s not practical because it would be too difficult to account for all the snails and/or shrimp and remove them, then I would suggest taking the salinity carefully down to about 1.017 in your main tank, which most of your janitors should tolerate just fine, after moving your seahorses to your hospital tank for treatment at full OST.

    Just set up your hospital tank at a salinity of 15-16 ppt (a specific gravity of 1.011-1.012) and adjust the water to the same temp and pH as the main tank. Then administer a freshwater dip to your seahorses, and transfer them directly into the hyposalinity treatment tank afterwards without any acclimation whatsoever.

    As I mentioned earlier, OST is completely compatible with most medications. (In fact, many medications are more effective at low salinity than they are in full strength saltwater.) Since secondary bacterial or fungal infections often accompany parasite problems, I would also recommend combining hyposalinity in the hospital tank with antibiotic therapy. In that case, simply medicating the hospital tank with the appropriate antibiotics will be easier than administering the antibiotics orally via gut-loaded shrimp. [CAUTION: if administering hyposalinity in your main tank, do not administer antibiotics, which may adversely impact the biofiltration in the aquarium.]

    Nifurpirinol used in conjunction with neomycin will be very effective for medicating the hospital tank during OST, as will the powerful combination drugs that contain both antiprotozoal and wide-spectrum antibacterial agents. Look for a product that includes ingredients such as nitrofurazone and metronidazole, which are very effective against protozoan parasites, as well as antibiotics such as neomycin and kanamycin, which are powerful broad-spectrum medications.

    If you do not see improvement within 4-5 days of administering OST, don’t hesitate to use the alternative treatments discussed for each particular parasite! They can be administered safely in conjunction with hyposalinity, bearing in mind the impact they will have on the biological filtration, or you can carefully return the salinity to normal and then treat with chemotherapeutics. When administering alternate treatments, check your ammonia/nitrite readings closely, and use water changes as needed to keep the levels of ammonia and nitrite at acceptable levels. Also, you are strongly advised to administer daily freshwater dips in addition to treating with chemotherapeutic agents if the alternative treatments are used in the absence of OST. The freshwater dips will provide the same benefits as hyposalinity and enhance the effectiveness of whatever treatment you employ to control the parasites.

    Modified OST for Reef Tanks

    Reefers generally run a modified version of OST in which they maintain a somewhat higher specific gravity, usually around 1.017 (Thiel, 2003), for a longer period of time in order to control protozoal parasites. Most corals are safe at even lower salinities, but 1.017 usually provides adequate protection and provides a margin for error. In any case, as a rule, reef keepers DO NOT take their systems lower than 1.015 for safety’s sake (Thiel, 2003). (This is also a good option for hobbyists who have only a typical pet-store hydrometer for measuring specific gravity, or anyone with many invertebrates in their seahorse setup.)

    Corals typically close slightly immediately after the salinity is lowered, but are open fully again by the next day, and suffer no harmful long-term effects from hyposalinity at 1.017 whatsoever (Thiel, 2003). Reefers who practice OST report that it has no long-term detrimental effects on the growth rate of their corals.

    According to Thiel, corals that are know to be sensitive to hyposalinity, and which are thus not well suited for OST, include Seriotopora hystrix, Montipora digitata, Pocillopora species and other similar hard corals with a fine, dense, polyp structure (Thiel, 2003). Acropora species, however, handle hyposalinity well and soft corals are also generally fine, including such sensitive softies as Xenia, Lemnalia, and the like (Thiel, 2003). As long as the pH and alkalinity are maintained at normal levels, most hard corals are not harmed at a specific gravity as low as 1.017.

    Don’t return any sensitive invertebrates to the main tank until the entire regimen of hyposalinity has been completed and the aquarium has been returned to normal salinity again, Capricorn.

    If you feel he can withstand it and is unlikely to survive without further intervention, you could administer a formalin bath to Fred exactly as directed in my previous post. Otherwise, osmotic shock therapy is the procedure I would suggest.

    If you are going to be relocating the delicate invertebrates and cleanup crew to the hex tank for the duration of the treatment, Capricorn, you could administer Parinox instead of or in conjunction with the hyposalinity.

    Here are some additional references that you may find helpful if you would like to look into the topic of hyposalinity as a treatment for marine fish in more detail:

    Colorni, A. 1985. "Aspects of biology of Cryptocaryon irritans and hyposalinity as a control measure in captive-raised gilt-bead sea bream Sparus aurata. Dis. Aquat. Org. 1: 19-22.

    Colorni, A. 1987. Biology of Cryptocaryon irritans and strategies for its control. Aquaculture, Vol. 67(1-2): 236-237.

    Frakes, Thomas. 1994. "Treatment of Cryptocaryon irritans in public aquaria." SeaScope, Editor’s Note, Summer 1994.
    Giwojna, Pete, and Carol Cozzi-Schmarr. 2003. "Horse Forum." Freshwater and Marine Aquarium, December 2003.

    Goodlett, R. and I. Ichinotsubo. 1997. "Salinity and pH adjustments for quarantine procedures for marine fishes." Drum and Croaker, Vol. 28: 23-26.

    Hauter, Stan and Debbie. 2004. "Saltwater Ich Diagnosis, Treatment and Prevention — page 7: Other Treatment Methods Continued – O.S.T. (Osmotic Shock Therapy)." (Accessed 28 Mar. 2004) <;
    Kollman, Rand. 1998. “Low Salinity as Quarantine and Treatment of Marine Parasites.” SeaScope. Aquarium Systems: 1,3.

    Lowry, Toby DVM. 2004. "Quarantine of Marine Fish (Teleost) Using Hyposalinity." Advanced Aquarist, November 2004. <;

    Thiel, Albert J. 2003. Parasites and Low Salinity. Accessed 7 Oct. 2003. <;

    Best of luck in eliminating the flatworms from your aquarium one way or another, Omar!

    Pete Giwojna, Ocean Rider Tech Support

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