Pete Giwojna
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Re:Kelloggi Seahorses - 2008/05/11 22:10
Dear Sandy:
Yeah, Sandy, it sounds like ectoparasites of some sort dropped off your H. kelloggi during the freshwater dips. The minute rice-like objects and the roundish particles could be flukes/trematodes or external parasites of some sort, and I suspect they were flushed out of your seahorse's gills during the freshwater dip. The whitish flakes could simply be mucus (excess mucous production is a common reaction to the irritation that results from parasitic infections).
I would recommend administering a treatment for parasites in your quarantine tank/hospital tank, and I think hyposalinity may be the best choice in this case. Reducing the specific gravity of the aquarium water to 1.015-1.017 will eradicate gill flukes and many protozoan parasites, and you could be begin treating the seahorses with reduced salinity right away, since it requires no medication. I will provide you with detailed instructions explaining how to administer the hyposalinity or osmotic shock therapy safely, Sandy. The hyposalinity basically provides the same sort of benefits as a freshwater dip, but it is much easier on the seahorses and can be maintained indefinitely until the parasites have been eliminated.
Your female H. erectus is suffering from the initial stages of ulcerative dermatitis of the tail tip, a condition which is commonly known as white tail disease or tail rot. This affliction can result from a number of causes. It can develop when a mechanical injury to the tail, such as a cut or scrape, becomes infected. Certain ciliates and protozoan parasites can attack the skin of seahorses, and when their integument is compromised, secondary bacterial and fungal infections may set in, resulting in tail rot. Likewise, cnidarian stings or the embedded spicules from a bristleworm can become infected and lead to tail rot. Many times an underlying bacterial infection (Vibrio, Pseudomonas or Mycobacterium) may be the primary cause of the tissue erosion and ulceration that's so characteristic of tail rot. It is often associated with heat stress, particularly in temperate seahorses that have experienced a temperature spike during a summertime heat wave.
The tip of the tail is especially prone to infection because blood-oxygen levels are often deficient in the extremities -- oxygen tension is lowest in the most distal part of the tail -- and the bacteria that are responsible for tail rot prefer a low oxygen environment. A dirty substrate can be a contributing factor in some cases, and stress is almost always involved. The seahorse's tail is prone to scrapes and abrasions as well as injuries such as stings from anemones or bristleworms spicules because it is used to grasp objects and often in contact with the substrate.
Disease-causing (pathogenic) bacteria such as the ones that cause tail rot are opportunistic invaders that are normally present in low numbers but don't cause problems until the fish is injured, stressed, infested with parasites or otherwise weakened (Indiviglio, 2002). They will then take advantage of the overtaxed seahorse's impaired immune system and reproduce extremely quickly, causing a variety of illnesses and problems (Basleer, 2000). Some of these are specific to seahorses, such as snout rot and white tail disease, and others are common to all fishes (Mycobacteriosis).
One of the best ways to prevent tail rot and other disease problems is to provide them with a stress-free environment. Many of the parasites and pathogens that plague our pampered ponies are ubiquitous -- present in low numbers in most everyone's systems or within the seahorse's body itself (Indiviglio, 2002). As a rule, healthy fish resist such microorganisms easily, and they only become a problem when seahorse's immune system has been impaired, leaving it susceptible to disease (Indiviglio, 2002). Chronic low-level stress is one of the primary factors that suppresses the immune system and weakens the immune response, opening the way to infection and disease (Indiviglio, 2002). Long-term exposure to stressful conditions is very debilitating. Among other effects, it results in the build up of lactic acid and lowers the pH of the blood, which can have dire consequences for seahorses for reasons we'll discuss later.
A progressive loss of prehensility and increasing discoloration beginning at the tip of the tail are the initial stages of tail rot or white tail disease. As I mentioned, it often affects the most distal portions of the tail first, where the oxygen tension is lowest and the circulation is the poorest, which seems to make the tail tip particularly susceptible to such infections.
Here is an excerpt on tail rot from my new book (Complete Guide to the Greater Seahorses in the Aquarium, unpublished):
White Tail Disease (Tail Rot)
As you might expect, this problem is due to an infection that attacks the tails of seahorses. The tip of the tail typically turns white and, as the infection spreads, the whiteness moves progressively up the tail and ulcers or open sores begin to form where the skin peels away (Giwojna, Oct. 2003).
Hobbyists usually refer to this problem as Tail Rot or White Tail Disease, but the disease is already well advanced by the time whitening or tissue erosion occurs (Giwojna, Oct. 2003). Early detection makes it much easier to get these infections under control. Some of the early indicators of a tail infection to watch for are discussed below.
The disease begins with a loss of prehensility in the very tip of the tail (Giwojna, Oct. 2003). At this stage, the seahorses can grasp large objects just fine, but cannot take hold of slender objects with a small diameter (Leslie Leddo, pers. com.). Next the loss of prehensility spreads further up the tail and the seahorses begin to act as if their tails are very tender and sensitive. They will drape their tails over objects rather than grasping onto them and begin to drag their tails behind themselves, often arching the end of their tail upward in the shape of "U" (rather than the usual "J" or tight coil) as if to lift it off the ground and keep it from touching anything (Leddo, pers. com.).
This is usually when the tip of the tail becomes white and the loss of coloration starts advancing further and further up the tail (Giwojna, Oct. 2003). At this point, the discolored skin begins to flake or lift up and open wounds and ulcers develop on the most distal portions of the tail (Giwojna, Oct. 2003). The infection attacks the underlying tissues, and the tail is gradually eaten away, often all the way to the bone, exposing the vertebrae (hence the name Tail Rot). Survivors may end up missing the last few segments of their tail (Giwojna, Oct. 2003).
White tail disease is highly contagious disease. I have seen it often in temperate seahorse species suffering from heat stress, as well as in crowded nursery tanks where it spreads through the fry like wildfire (Giwojna, Oct. 2003).
Infected seahorses should be treated with antibiotics in isolation at the first sign of a loss of prehensility in the tip of their tails (otherwise the antibiotics may harm the biofilter in your main tank, creating more problems). There are a few treatment options to consider. Feeding the seahorses with live shrimp that have been gut-loaded or bio-encapsulated with tetracycline/oxytetracycline or minocycline sometimes produces good results (Giwojna, Oct. 2003).
But the treatment I recommend is gradually dropping the temperature of the aquarium, hitting the infection hard with broad-spectrum antibiotics in a hospital tail, and administering Beta Glucan orally to stimulate the seahorse's immune system and help the affected seahorse fight off the infection.
I'm not sure if penicillin will be helpful in treating this condition, Sandy, but tetracycline antibiotics administered orally and the following antibiotics are known to be effective in treating tail rot: Neosulfex and Neo3 -- both broad-spectrum antibiotics consisting of neomycin combined with sulfa compounds to produce a potent synergistic combination of antibacterials -- are the antibiotics available to hobbyists that seem to work best for tail rot. Unfortunately, Neosulfex is no longer available but you may be able to obtain Neo3 from the following vendor:
http://www.seahorsesource.com/cgi-bin/shop/search.cgi?&category=Medications
If not, most hobbyists have been getting similar results by creating their own version of these medications by combining neomycin sulfate with various sulfa compounds. One that seems to work well is combining neomycin sulfate with triple sulfa. You may be able to get neomycin sulfate and triple sulfa compound at a well-stock LFS. If not, you can obtain both neomycin sulfate powder and triple sulfa powder from National Fish Pharmaceuticals. You can order them online at the following site: http://www.fishyfarmacy.com/products.html
Kanamycin sulfate used alone or in conjunction with neomycin sulfate would also be an excellent choice for treating tail rot. Both of these antibiotics are often available at pet shops and fish stores, and they can both be obtained from National Fish Pharmaceuticals as well.
As I mentioned above, tetracycline in oxytetracycline can be effective treatments for tail rot when they are administered orally. However, they are useless as bath treatments for marine fishes. This is because calcium and magnesium bind to tetracycline and oxytetracycline, rendering them inactive (Roy Yanong, US Department of Agriculture). Adding tetracycline or oxytetracycline to saltwater in a hospital tank is therefore completely ineffective (Yanong, USDA), but administering the antibiotics orally can produce good results.
Reducing the water temperature in the hospital tank will further increase the effectiveness of the antibiotics and help your seahorse recover faster. Heat stress is often associated with tail rot and is especially debilitating and dangerous for seahorses due to a number of reasons (Olin Feuerbacher, pers. com.). For one thing, elevated temperatures can have a very detrimental effect on the immune system of fishes. This is because many of the enzymes and proteins involved in their immune response are extremely temperature sensitive (Olin Feuerbacher, pers. com.). Some of these protective enzymes can be denatured and inactivated by an increase of just a few degrees in water temperature (Olin Feuerbacher, pers. com.). So when seahorses are kept at temperatures above their comfort zone, their immune system is compromised and they are unable to fend off diseases they would normally shrug off.
At the same time heat stress is weakening the seahorse's immune response, the elevated temperatures are increasing the growth rate of microbes and making disease organisms all the more deadly. Research indicates that temperature plays a major role in the regulation of virulence genes (Olin Feuerbacher, pers. com.). As the temperature increases, virulence genes are switched on, so microorganisms that are completely harmless at cooler temperatures suddenly become pathogenic once the water warms up past a certain point. Thus both the population and virulence of the pathogens are dramatically increased at higher temperatures (Olin Feuerbacher, pers. com.).
This is true of Columnaris and certain types of Vibrio. At cool temperatures these bacteria are relatively harmless, but at elevated temperatures they become highly contagious, virulent pathogens that kill quickly. Neil Garrick-Maidment, director of the Seahorse Trust in the UK, reports that he stopped a deadly outbreak of Vibrio among his Hippocampus capensis dead in its tracks and cured the seahorses simply by cooling their aquarium down to 18°C (64.4°F) for a period of weeks. The bacteria simply no longer presented a problem at that temperature:
[Quote]
I am not sure if it is of any help but I recently had a problem with vibriosis
in Hippocampus capensis coupled with a couple of gas bubbles in the end of the
tail. Having tried a number of treatments in the past that havn't worked I took
a slightly more drastic approach this time and dropped the temperature from 23°C (73.4°F) down to 18°C (64.4°F) having first isolated the infected animals into a separate
tank. I then left them like this for 4 weeks after which I increased the
temperature slowly up to 21°C (70°F), which it still is. After the second week
the vibriosis had gone completely (and has not returned) and the gas bubbles
were gone after the third week. In all the time the temperature was low the
animals reduced their feeding and it has now increased with the raising of the
temperature and they since gone on to have two broods of fry.
Best wishes,
Neil Garrick-Maidment
Seahorse Project Co-ordinator
In short, it makes a lot of sense to reduce the aquarium temps while trying to get an infection such as this under control. Cooling down the microbes and slowing their metabolism and rate of reproduction accordingly can slow any bacterial infection (Giwojna, Oct. 2003).
Tropical seahorses will be fine as low as 68°F (20°C) providing you drop the water temperature gradually. But the temperature does not need to be reduced markedly to have a very beneficial effect on a bacterial infection; just dropping the water temperature a few degrees will be very helpful.
One simple way to drop the water temp in your aquarium is to position a small fan so it blows across the surface of the water continually (Giwojna, Oct. 2003). This will lower the water temperature a several degrees via evaporative cooling (just be sure to top off the tank regularly to replace the water lost to evaporation). Leaving the cover/hood and light off on your seahorse tank in conjunction with evaporative cooling can make a surprising difference.
In a pinch, some hobbyists will even freeze plastic bottles 3/4 full of water and float the frozen bottles of water in their tank during the hottest part of the day. If necessary, that may worth trying in your case too, depending on how well your aquarium temp responds to the other measures.
Here are some additional suggestions on cooling down your aquarium from Renée at the org that you may also find helpful:
Some summer tips are:
• Use computer fans (you can wire them to AC adapters... we are making some this weekend for our tanks).
• Use a big ol clip-on-fan or a fan on a stand that you can set close. (Just be mindful of water evap.)
• Float ice containers in the tank (Use water/liquid that you wouldn't care if it sprung a leak. Those blue lunch/picnic type cooling things are not acceptable IMO.... what if it leaks? It will kill everything. I would recommend using bottled ice water because it will stay frozen even longer than fresh water..... but if you do use fresh water make sure it is water you wouldn't mind spilling into the tank.... good ole tap water is not acceptable.)
• If you have a hood or canopy on the tank.....keep it off or lifted.
• Cool down the room the tank is in by using a portable or window AC unit. The window units can be pretty cheap.
• If the sun really heats up this room, look into some window tinting. This is what I did when I lived in South Texas. It dropped the room temp TEREMENDOUSLY! (If ya wanna go the cheap method, foil was used in many windows in the city I lived in... wasn't the prettiest method but it saved many people lives who lived in places without central AC and couldn't afford well working window units.)
• Shorten your photoperiod.... if possible don't have the lights on in the hottest past of the day. But at any rate, shorten the amount of hours the lights are on for.
HTH
Renée
When reducing the water temperature via evaporative cooling, I should also caution you to observe all the usual precautions to prevent shocks and electrical accident when you are using an electric fan or any other electrical equipment on your aquarium, Sandy.
One such precaution is to install an inexpensive titanium grounding probe in your aquariums. That will protect your seahorses and other wet pets from stray voltage and should also safeguard them electrocution in the event of a catastrophic heater failure or similar accident..
But the best way to protect you and your loved ones from electrical accidents around the fish room is to make sure all the outlets are equipped with Ground Fault Circuit Interrupters. And it's a good idea to make sure all your electrical equipment is plugged into a surge protector as well to further protect your expensive pumps, filters, heaters, etc. from damage. Some good surge protectors, such as the Shock Busters, come with a GFCI built right into them so you can kill two birds with one stone. So when you set up your cooling fan(s) on the aquarium, be sure they're plugged into a grounded outlet with a GFCI or a surge protector with GFCI protection.
Finally, adding beta glucan to your treatment regimen to boost the healing seahorse's immune system can also help them fight off this infection. The best way to administer the beta glucan is simply to enrich frozen Mysis with Vibrance and feed it to your seahorse as usual. The Vibrance formulations now include Beta Glucan, a potent immunostimulant, as a primary ingredient. As a result, we can now boost our seahorse's immune systems and help them fight disease as part of their daily feeding regimen. Enriching our galloping gourmets' frozen Mysis with Vibrance will give them a daily dose of Beta Glucan to stimulate phagocytosis of certain white cells (macrophages). If the research on Beta Glucan is accurate, this could be a great way to help prevent infections from bacteria, fungus, and viral elements rather than attempting to treat disease outbreaks after the fact.
Not only should Vibrance + Beta Glucan help keep healthy seahorses healthy, it should also help ailing seahorses recover faster. Research indicates that it helps prevent infections and helps wounds heal morfe quickly (Bartelme, 2001). It is safe to use in conjunction with other treatments and has been proven to increase the effectiveness of antibiotics (Bartelme, 2001). It will be great for new arrivals recovering from the rigors of shipping because Beta Glucan is known to alleviate the effects of stress and to help fish recover from exposure to toxins in the water (Bartelme, 2001) . Good stuff!
For more information on the potential benefits of Beta Glucan for aquarium fish, please see the following article:
Click here: Advanced Aquarist Feature Article
http://www.advancedaquarist.com/issues/sept2003/feature.htm
Adminstering Beta Glucan orally via Vibrance-enriched frozen Mysis, which are so naturally rich in highly unsaturated fatty acids (HUFA), is the perfect way to boost the immune response of our seahorses since vitamins and HUFA enhance the capacity of immune system cells that are stimulated by the use of beta glucan (Bartelme, 2001). .
If the tail rot is detected early, it should respond well to a treatment regimen consisting of antibiotic therapy, reduced temperature, and beta glucan administered orally. Topical treatments consisting of dipping the tail of the seahorse in disinfectants such as Betadine can also be a useful addition to the other therapies for tail rot we have been discussing. All antibiotics are safe to use with hyposalinity, so reducing the specific gravity in your quarantine tank/hospital tank while you administer the antibiotics is perfectly appropriate. Your H. kelloggi might benefit from the antibiotic therapy as well, since secondary infections following parasitic infections are commonplace, so don't hesitate to treat all of seahorses together.
Here are the instructions for administering hyposalinity safely, Sandy (in your case, you can skip the freshwater dip since your H. kelloggi have already had freshwater dips):
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 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.
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.]
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.
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) <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>
Thiel, Albert J. 2003. Parasites and Low Salinity. Accessed 7 Oct. 2003. <http://netpets.com/fish/healthspa/parsalin.html>
Increase the aeration in your hospital tank while you are treating the seahorses, if possible, Sandy, in order to assist their breathing. The hyposalinity will help in that regard because the aquarium water can hold more dissolved oxygen at the reduced specific gravity.
Best of luck treating your ailing seahorses, Sandy
Respectfully,
Pete Giwojna
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