by Pete Giwojna

In the previous issue of Conscientious Aquarist (May/June 2007), we discussed and experimental Angelfish community aquarium that was maintained at a salinity of 15 parts per thousand (ppt), or a specific gravity (SG) of 1.011, as a disease prevention measure.  In this article, we will explain the benefits of hyposalinity in more detail and consider when it is appropriate for a marine aquarium and when it should only be used in modified form or avoided altogether.  Editor's note:  That angelfish aquarium drew a lot of criticism from the WetWebMedia community, and we don't wish to condone such heavy stocking levels.  It should be noted that while hyposalinity is a valuable tool for such systems, the fact that it is necessary is an indication that the system is being pushed to the limit.

As you might expect from its name, hyposalinity or osmotic shock therapy (OST) is a method of disease treatment that simply involves maintaining a marine aquarium at a much lower salinity than normal.  For fish only systems, a salinity of 11 ppt (1.008 SG) is recommended for best results (Lowry 2004) when treating protozoan parasites.  In aquaria housing delicate invertebrates, such as reef systems, a modified form of OST that uses a somewhat higher salinity around 22-23 ppt (1.017 SG) is often employed to control outbreaks of parasites (Thiel 2003).  In general, the salinity most often used for OST and cited in the literature is 16 ppt or a specific gravity of 1.012 (Lowry 2004), which is a good compromise for most systems.

Hyposalinity can be an effective technique for disease control because Marine Ich (Cryptocaryon irritans), external trematodes, and most ectoparasites and protozoan parasites cannot survive for long at such low salinity.   This is because such parasites lack the efficient bodily mechanisms for osmoregulation that allow teleost fish to adjust to the reduced salinity. At the salinities appropriate for OST, water thus continues to move into the parasites' bodies via passive diffusion until they literally burst (lyse) or are killed by the osmotic shock. When the salinity is maintained at the proper level, these ectoparasites or eliminated but the fish they were infesting are fine.  A noteworthy exception to this is Amyloodinium (marine velvet).  Amyloodinium is very well adapted to low salinity and almost completely unaffected by hyposalinity.

Essentially, OST simply places the infectious organisms in an environment in which they cannot long 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. This low salinity method of treatment 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.

Hyposalinity or OST is therefore my treatment of choice whenever there is an outbreak Cryptocaryon, trematodes, or protozoan parasites in a community tank.  Not only does it destroy such parasites in the aquarium water and on the bodies of their hosts, hyposalinity also helps parasite-ridden fish avoid dehydration and save their strength by reducing osmotic pressure and making it easier for them to osmoregulate.  

Because the seawater they live in is far saltier than their blood and internal body fluids, marine fish are constantly losing water by diffusion through their gills and the surface of their skin, as well as in their urine. 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 compromised by abrasions or 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.  

OST kills the free-swimming parasites, preventing the affected fish from being reinfected and helping to avoid dehydration.  This makes it easier for the weakened fish to osmoregulate and helps conserve their bodily resources for healing.  Hyposalinity or OST is totally noninvasive and harmless to teleost fish in general, can be administered safely in the display tank rather than a hospital tank to eradicate protozoan parasites from your system, and is completely compatible with UV and any medications you may be using.

And since most of the bacterial and fungal problems that plague marine fish are secondary infections that take hold after the fish's integument has been compromised by a mechanical injury or external parasites, eliminating those ectoparasites via hyposalinity also helps minimize problems with bacteria and fungus. 

Hyposalinity is also believed to be helpful in treating marine fish with damage to their skin coat or mucus layer due to abrasions or mechanical injuries, or resulting from ulcerative dermatitis caused by bacterial infections such as Pseudomonas or vibriosis (Lowry 2004).  The same mechanisms that help fish recover from parasitic infections that attack the skin and gills are thought to be beneficial in helping fish with open sores and ulcers to osmoregulate and avoid dehydration, and may therefore aid their recovery.  As Toby Lowry (DVM at the Oklahoma Aquarium) puts it, "In theory, the reduction of the osmolar gradient between the internal tissues and the surrounding environment would be beneficial to injured mucus and epidermal tissue. This reduction in the osmolar gradient, in theory, greatly reduces the loss of water from the fish to the surrounding environment. The ability to maintain hydration in an injured marine fish too small to administer fluids could prove very beneficial (Lowry 2004)." 

In short, hyposalinity or OST is appropriate whenever there is an outbreak of Cryptocaryon, external trematodes, or protozoan parasites other than Uronema in a fish only tank.  And it can be useful part of the treatment regimen in a hospital tank that can safely be combined with antibiotic therapy when medicating fish with skin infections or ulcerative dermatitis.  But it is especially useful when isolating new arrivals in your quarantine tank prior to introducing them to your main tank.  Newly obtained fish from your local fish store are especially vulnerable to outbreaks of marine ich (Cryptocaryon irritans), marine velvet (Amyloodinium), and a host of other parasitic infections, and maintaining hyposalinity in your hospital tank can help control such problems during this high-risk period without the use of harsh chemotherapeutics such as copper sulfate or formalin.  It is perfectly safe to maintain a salinity of 11 ppt (1.008 SG) for up to 30-45 days (Lowry 2004), which is more than enough time to allow for the incubation period and life cycle of the common parasites that plague marine fish.

However, hyposalinity is by no means a cure all.  It does not have any affect whatsoever on internal parasites or primary bacterial and fungal infections.  That is to be expected, of course, since the internal tissues would maintain a static osmolar concentration within the body of the fish (Lowry 2004).  And there is at least one protozoan parasite that does not respond well to OST.  Uronema marinum, a ciliated unicellular parasite seems to tolerate hyposalinity very well, and the use of hyposalinity is contraindicated in the case of these euryhaline parasites.  Last, but no least, as previously mentioned, hyposalinity is not effective against Amyloodinium.

CAUTION: hyposalinity or OST is not safe for all marine fishes!  Keep in mind that elasmobranches such as sharks and rays do not tolerate reduced salinity well, and OST is not appropriate or recommended for these cartilaginous fishes.  Bony fishes (teleosts) in general tolerate hyposalinity very well, with one or two provisos.

For example, Seahorse keepers should be aware that hyposalinity works great for Hippocampus, but only up to a certain point.  Do not attempt to treat seahorses with hyposalinity at a specific gravity below 1.010! 

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 extremely well, but only so far; some species cannot withstand salinities below 13.3 ppt (specific gravity = 1.010) for extended periods. Salinities below 1.010 may be fatal to some seahorses in a matter of days, if not hours.

In the old 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). These experiments were repeated with several groups of seahorses representing different subspecies of H. erectus, and the results were always the same: fine as low as 1.010 -- defunct at 1.009 (Bellomy 1969)!

Keeping that in mind, it is best for Seahorse keepers to make their target salinity 1.011-1.012 to allow a margin for error, and to transfer their ponies to a hospital tank while they drop the salinity in the main tank.  That way, no harm will be done if the hobbyist accidentally takes the salinity down too far in their 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.  

The same precautions recommended for seahorses also apply to most species of clownfish (Amphiprion spp.).  Some Clownfish cannot tolerate freshwater dips, and these clowns should be treated in the same manner as Seahorses when administering hyposalinity to be safe.

Administering Osmotic Shock Therapy

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 RO water or detoxified tap 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 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 by osmosis into the parasites' bodies until they literally explode. As a higher life form, the fish can withstand this treatment very well and quickly adjust to the reduced salinity; invertebrates and parasites cannot (Don Carner, pers. com.).  

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. A 6 week treatment period even more effective and is the recommended treatment protocol.  For example, the Oklahoma Aquarium routinely quarantines all of their marine display fish (i.e., teleosts) at a salinity of 11 ppt (1.008 SG) for 30-45 days (Lowry 2004).

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, it would be a good idea to aim for a moderate level of hyposalinity, such as 16 ppt (1.012 SG) which will allow a reasonable margin for error in case your hydrometer is reading a little high or a little low.  If you do decide to try hyposalinity using a hydrometer, 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.

In addition, when administering OST it is important to monitor your ammonia and nitrite levels closely at first.  Although I have never had a problem in that regard, it's possible that 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, in some instances, 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 3-6 week treatment period is over, gradually 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.  However, when returning the salinity to normal, it's extremely important to 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.  In addition, the aquarium water will can hold less and less dissolved oxygen as the salinity is raised, so there is a potential for gas supersaturation to occur if the salinity is raised too quickly.  Don't hesitate to take a full week or more 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 delicate fish 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.  [Editor's note:  Corals and other invertebrates should never be exposed to hyposalinity!]

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, 2001). 

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. 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 (1.011 SG), while sixteen other 30-gallon tanks, connected to their own separate filtration system, were maintained at normal salinities of 27-30 ppt (1.020-1.022 SG) and served as the control group for the experiment (Kollman, 1998). Both systems had identical filtration and were maintained at the same temperature (between 79°F-80°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, 2003). No differences in behavior were observed between the fishes in the two systems during the trial period.  

The results of the three-year study were dramatic and conclusive. 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). 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).  

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). He concluded that a salinity of 14 to 15 ppt (1.010-1.011 SG) was an effective treatment level to which fish can be immediately transferred with no special acclimation procedures (Kollman, 1998). 

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)! Likewise, as indicated in the illustrations for this article, a number of exotic fish in Travis Carter's experimental angelfish community tank have been thriving at a salinity of 15 ppt (1.011 SG) for nearly a year now.  However, hobbyists should be aware that the long-term effects of hyposalinity are still unknown and poorly understood, and that it is not intended or recommended for long-term use in normal applications.  The proper use of OST is to maintain the hyposalinity throughout the quarantine period for new arrivals, or the treatment period (i.e., 30-45 days) needed to clear up an outbreak of parasites, and then to very gradually return the salinity to normal levels 

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. 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) and he reaffirmed those findings in another report two years later (Colorni, 1987). Randolph Goodlett and Lance Ichinotsubo have likewise reported their own low-salinity treatment techniques, recommending at least 3 weeks exposure at 14 ppt (1.010 SG) 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).

Hyposalinity Pros: 

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, Indian Ocean, Indo-Pacific, Florida & Caribbean, Australia).

5. Minimizes secondary bacterial and fungal infections. 

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, and leeches.

9. Prevents the spread of protozoal parasites in general.

10. Reduces the risk of dehydration when the integrity of the fish' slime coat is impaired.

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. Increases dissolved oxygen levels in heavily stocked systems.

16. Can be used safely with protein, skimmers, ozone, UV, and other treatments.

17.  Provides a noninvasive method of treatment that can safely be used to treat the main tank in fish only systems. 

Hyposalinity Cons: 

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. Contraindicated in cases of Uronema.

7. Has no effect on internal parasites or primary bacterial and fungal infections.

8.  May impact nitrifying bacteria in the biofilter temporarily.

9. 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).

10. 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. Nerites and periwinkles don't mind it at all, others are okay at 1.017 but you can kiss them goodbye at 1.010 or below. Most corals are vulnerable to full OST. 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, 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.

For a standard fish-only-with-live-rock setup with a clean-up consisting of assorted snails, hermits, and cleaner shrimp, I recommend relocating the snails and shrimp while treating your aquarium system with full OST at a specific gravity of 1.008 (salinity = 11 ppt) 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 fish to your hospital tank for treatment at full OST.

Just set up your hospital tank at a salinity of 11 ppt (1.008 SG) and adjust the water to the same temp and pH as the main tank. Then administer a freshwater dip to the affected fish 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. [CAUTION: if administering hyposalinity in your main tank, do not administer antibiotics, which may adversely impact the biofiltration in the aquarium.]

Combining aminoglycoside antibiotics such as kanamycin or neomycin with sulfa compounds (e.g., Triple Sulfa or Trisulfa) 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. And, of course, combining hyposalinity with formalin in your hospital tank will be extremely effective in treating ectoparasites.

If you do not see improvement within 4-5 days of administering OST, don't hesitate to use the alternative treatments such as copper sulfate or formalin! 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 nitrate in your hospital tank 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 use a somewhat higher specific gravity, usually around 1.017 (Thiel, 2003), but maintain it 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.  [Editor's note:  Be aware of the fact that during hyposalinity treatments, everything in the water is diluted in proportion to the salinity, including alkalinity and calcium which can definitely impact coral growth.]

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. 

In conclusion, when administered properly, hyposalinity or osmotic shock therapy offers many benefits and advantages to aquarists as a means of disease prevention and control.  It is ideal for quarantining new arrivals during the high-risk period of adjustment.  It provides a safe, noninvasive means of treating your display tank when there is an outbreak of ectoparasites in fish only systems, and is my treatment of choice for marine ich (Cryptocaryon irritans).  And it provides reef keepers with a means of treating their fish when a problem with parasites occurs and the only other option is often to sacrifice the fish.  Don't hesitate to give it a try under the right circumstances.

References 

Bellomy, Mildred D. 1969.  Encyclopedia of Seahorses.  Jersey City, NJ: TFH Publications.

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) <http://saltaquarium.about.com/cs/diseasesich/a/aa102797f_2.htm>

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.  <http://www.advancedaquarist.com/issues/nov2004/short.htm>

Taylor, Gregory S.  2001.  Salty Zoo: Salinity Adjustment Calculator.  22 Nov. 2001.  Accessed 27 Mar. 2004.  <http://saltyzoo.com/SaltyCalcs/SalinityAdjust.php>

Thiel, Albert J.  2003.  Parasites and Low Salinity.  Accessed 7 Oct. 2003. <http://netpets.com/fish/healthspa/parsalin.html>