new seahorse failure

sorry about your seahorse. Mine is doing the same thing. my levels are good and i don’t know what to do.. 🙁

Dear FERS4REEF:

It’s very difficult to determine what may be wrong with your seahorses with so little to go on, but for whatever it’s worth, I would be happy to share my thoughts on the matter with you. If there are no open sores or ulcerations, no areas of depigmentation or other signs of a skin infection, no buoyancy problems, and the only obvious symptom is heavy breathing, then my best guess is that either your dissolved oxygen levels are too low or the seahorses are having a problem with some sort of gill parasites.

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, seahorses are particularly susceptible to low oxygen levels and asphyxia.

For starters, consider adding an ordinary airstone to your tank, anchored just beneath the surface of the water. That will add surface agitation, extra aeration, and promote more efficient gas exchange at the air/water interface. Unless you’re quite certain your system already has plenty of water movement, it is also advisable to increase the water circulation, just as Suzanne suggested. If your filter is not adjustable, one simple way to increase the water movement and eliminate dead spots in your aquarium is to add a small powerhead for extra circulation. Seahorses can handle more water movement than most folks realize, and you can always turn it off during feedings. Just screen off the intake for the powerhead as a precaution so it can’t accidentally suck up a curious seahorse.

Aside from your basic water quality tests (ammonia, nitrite, nitrate, and pH), I also recommend that you use a test kit for measuring the dissolved oxygen in your seahorse setup in the future. The reason for this is that a drop in the level of dissolved oxygen is a great early warning indicator that something is amiss in the aquarium, and can thus predict potential problems (and allow you to take corrective measures) BEFORE they become full-fledged disasters. 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.

The Tetra Oxygen Test Kit (TetraTest 02) is an adequate 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 (the optimum dissolved O2 level is 6-7 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.

Secondly, it would be advisable to treat your seahorse tank to eliminate any parasites that may be present at which could be contributing to the seahorses’ respiratory distress. Depending on what other specimens are in the aquarium other than your seahorses, this could be accomplished either by treating the tank with an anti-parasitic that won’t impair the biological filtration such as Parinox or by adjusting the salinity of the aquarium to maintain hyposalinity for a period of 6-8 weeks, as discussed below:

Providing your seahorse tank doesn’t include any delicate invertebrates (live corals, shrimp, snails, etc.) that might be harmed by the medication, one good way to eliminate gill parasites would be to treat your main tank with Parinox, which eradicates a wide range of different ectoparasites very effectively, as described below:

Parinox

USE: For Ich, hexamita, costia, ichthyophthirius, ectoparasites, monogenia, hirudinea, parasitic copepods, argulus, lernaea, anchor worms, fish lice, leeches. Also a protozoacide. Anti-bacterial, anti-parasitic, very wide spectrum.

DOSAGE: Use 1/4 teaspoon per 20 gallons. Treat once a week for 2 weeks. If water changes are done, add back the percentage of medication according to how much water was changed.

You can obtain Parinox online from National Fish Pharmaceuticals at the following URL:

Click here: Fish Medications
http://www.fishyfarmacy.com/products.html

As you can see, the medication is effective against all of the ectoparasites and protozoan parasites that attack the gills and skin of fish. It’s a good medication to use in situations like this where were not sure exactly which parasites you may be dealing with Although Parinox is safe for seahorses, it can be hard on crustaceans and certain invertebrates. I don’t believe it will impair your biofiltration at all, so you can use it to treat the main tank and eradicate any parasites it may be harboring providing your tank does not include a lot of sensitive invertebrates. Ideally, it’s best to treat the main tank when there’s an outbreak of parasites to prevent reinfestation, so I would talk to fishyfarmacy over the phone and explain exactly what you have in your tank so they can determine whether or not Parinox would affect any of the other specimens.

If your aquarium include sensitive invertebrates that cannot be moved during the treatment, then you might consider treating the main tank with hyposalinity instead. If you think that might be a better option for you, please let me know right away and I will provide you with detailed instructions explaining exactly how to treat your seahorse tank with hyposalinity safely.

Finally, I would suggest performing a freshwater dip on the seahorse that his breathing heavily as a first aid measure, as explained below:

Freshwater Dips

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 freshwater dip, 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 and certain gill flukes will appear as opaque sesame seeds drifting in the water (Giwojna, Aug. 2003) and 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.

Best of luck correcting this problem and getting your remaining seahorse healthy again, FERS4REEF.

Respectfully,
Pete Giwojna

Dear FERS4REEF:

Thank you very much for the additional information — that certainly does help clarify things.

I think your initial diagnosis of marine ich (Cryptocaryon irritans) is very likely correct. It’s a fallacy that seahorses don’t suffer from Cryptocaryon. They do have some built-in resistance to it due to their exoskeleton and mucus layer, but that’s simply means that the telltale white spots are often not as evident on the body of the fish. The Cryptocaryon irritans parasites can still invade the gills of the seahorses, and masked infections of Cryptocaryon kill many more seahorses than hobbyists suspect.

As you know, marine ich or Cryptocaryon is a very common affliction on new arrivals that you bring home from your LFS, so if your pet shop ponies are exhibiting respiratory distress, refusing to eat, and displaying discrete white spots within two days of bringing them home, it’s extremely likely that they do indeed have Cryptocaryon. Both Parinox and hyposalinity or osmotic shock therapy will eliminate Cryptocaryon very effectively. So you could either obtain the Parinox from National Fish Pharmaceuticals and treat your seahorse tank, removing the snail and hermit crabs until after the treatment regimen has been completed, or reduce the salinity in your aquarium to the recommended levels for hyposalinity for a period of 6-8 weeks. Either procedure will eliminate marine ich.

In the meantime, freshwater dips can provide the infected seahorse with some quick relief by destroying many of the parasites on the body and the gills of the seahorse. But the fish will quickly be reinfest once it’s returned to the seahorse tank, so that’s only a first aid measure that can provide temporary relief and buy you a little time. I would recommend that you perform a freshwater dip on the seahorse followed by a brief 10-second dip in concentrated methylene blue as soon as possible, and then treat the seahorse tank either using hyposalinity or Parinox or both to eliminate the Cryptocaryon from the aquarium.

We have already discussed how to administer a freshwater dip properly and the instructions for performing the very short depth of methylene blue are as follows:

Methylene blue helps hemoglopin transport oxygen to restore normal breathing and can also help control protozoan parasites such as Cryptocaryon and certain bacteria by virtue of its ability to bind to cytoplasmic structures within their cells.

Commonly known as "meth blue" or simply "blue," this is a wonderful medication for reversing the toxic effects of ammonia and nitrite poisoning. Methylene blue transports oxygen and aids breathing. It facilitates oxygen transport, helping fish breathe more easily by converting methemoglobin to hemoglobin — the normal oxygen carrying component of fish blood, thus allowing more oxygen to be carried through the bloodstream. This makes it very useful for treating gill infections, low oxygen levels, or anytime your seahorses are breathing rapidly and experiencing respiratory distress. It is the drug of choice for treating hypoxic emergencies of any kind with your fish. However, methylene blue will destroy nitrifying bacteria so it should be used in a hospital tank or as a brief bath or dip only (if used in an established aquarium, it will impair the biological filtration and the tank may need to be cycled all over again).

If you can obtain the Kordon brand of Methylene Blue (available at most well-stocked local fish stores), there are instructions for administering it as a very brief, concentrated dip are as follows:

For use as a dip for treatment of fungus or external parasitic protozoans and cyanide poisoning:
(a) Prepare a nonmetallic container of sufficient size to contain the fish to be treated by adding water similar to the original aquarium.
(b) Add 5 teaspoons (24.65 ml) per 3 gallons of water. This produces a concentration of 50 ppm. It is not recommended that the concentration be increased beyond 50 ppm.
(c) Place fishes to be treated in this solution for no longer than 10 seconds.
(d) Return fish to original aquarium.

When you administer such a dip, hold the seahorse in your hand throughout the procedure and time it closely so that the dip does not exceed 10 seconds.

I wouldn’t count on your ultraviolet sterilizer to cure this problem. How effective the UV may be a controlling these parasites depends on the dwell time, wavelength of the UV, and many other factors, and in any case, it is only helpful in killing the parasites in their free-swimming stage and will have no effect on the parasites that are already embedded in your seahorse’s body or gills. The ultraviolet sterilizer can be very helpful in preventing disease outbreaks in the future, but it will not clear up a case of Cryptocaryon after the fact. So I think your best bet is to use either the Parinox or hyposalinity or both to control this problem.

If you’re going to order the paradox and wait for to arrive, I would suggest administering a daily freshwater dip to the seahorse at least until the medication arrives. If you want to try the hyposalinity instead, you could begin treating the tank immediately. Here are the instructions for performing hyposalinity or osmotic shock therapy safely:

Osmotic Shock Therapy (OST)

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 water 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).

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: http://saltyzoo.com/SaltyCalcs/SalinityAdjust.php

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.

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.
Best of luck clearing up this problem, FERS4REEF. Once you eliminate the Cryptocaryon irritans, your seahorse is going to be feeling a great deal better and should begin feeding again as a result.

Respectfully,
Pete Giwojna