Sick Seahorse with silvery/brass color patch on side

Dear Lola:

I’m very sorry to hear about the difficulties you been having with your seahorses over the years.

My best bet is that you have a disease reservoir in your tank, which could be within the seahorses’ bodies themselves or in the aquarium system, harboring within the substrate or filtration media perhaps, as an example.

When the seahorses are healthy and their immune system is strong, they are able to thrive despite the presence of low numbers of the disease pathogens. However, when the ponies are stressed for any reason, and their immune system becomes weakened and impaired as a result, they can no longer resist the disease organisms and they develop an infection because their compromised immune system is unable to fight off the infection in its initial stages.

Many pathogens and parasites are ubiquitous, present in low numbers throughout the aquatic environment, even under sanitary conditions in well-maintained aquariums with healthy fish. Although the fish are exposed to these ever-present potential pathogens, they remain healthy because their immune systems are able to effectively overwhelm the low level of the pathogens they encounter and because the sanitary conditions do not favor the pathogens or infectious organisms.

However, if something impairs or suppresses the immune system of the seahorses, or if the conditions change so that they are more favorable to the pathogens, then the infectious organisms can overwhelm the immune system of the seahorses, and they will fall ill. That is how many primary infections in seahorses and other marine fish get started.

A good example of how such illnesses work is the AIDS virus, which destroys the immune system of its hosts. Victims of AIDS are not killed by the virus, but with their immune systems incapacitated, they are very susceptible to normally harmless infections and germs that people with normal immune systems simply shrug off with ease, none the worse for wear. Thus AIDS victims typically die as a result of pneumonia or cancers that they would never have contracted and the first place if their immune systems were healthy.

Another example that is easy for people to relate to is a simple cut or scraped knee or elbow that your child suffered at the playground. If you did not carefully wash out the cut or scrape and then apply a good anti-septic and/or antibiotics salve to the injury, there is a good chance it could become infected. This would happen not because your child was exposed to another youngster with an infected cut or bruise, but because the germs or infectious organisms that can cause such infections are ubiquitous throughout the environment, and gained easy access to the bloodstream or damaged tissue through the injury. (That’s how secondary infections generally occur, and many cases of tail rot and snout rot in seahorses are the result of minor cuts or abrasions that go unnoticed.)

Likewise, if you stepped on a rusty nail and punctured your foot, the first thing your doctor would do would be to give you a tetanus shot as a precaution in order to prevent a potentially deadly infection from setting in at the site of the wound. He would do this not because you had been exposed to someone afflicted with lockjaw, but rather because tetanus germs are ubiquitous, and commonly found throughout the environment, so there’s no sense taking any chances that you might develop a dangerous infection as a result of the injury.

That’s the case with many of the common diseases in seahorses as well, Lola. This includes Vibrio infections, mycobacteriosis, Uronema, fungal infections, and even intestinal parasites. These pathogens are ubiquitous, commonly found in any aquarium system, or sometimes even within the body of the fishes themselves, but are normally present in small numbers and cause no problems for healthy seahorses until something happens that stresses the seahorses, weakens their immune system, or creates conditions that favor the pathogen or trigger its virulence genes.

For example, many species of Vibrio are natural aquatic flora that are present in all aquarium systems. They are opportunistic invaders that normally only get out of hand and cause problems when something tips the balance in their favor (e.g., deteriorating water quality or low dissolved oxygen levels), a wound or mechanical injury gets infected, or something stresses the seahorses to the point that their immune system is suppressed, leaving them vulnerable to disease. They are typically benign and nonpathogenic until something switches on their virulence genes or creates conditions that favor their growth.

In many cases, it’s an environmental problem that triggers a disease outbreak, such as a spike in the ammonia or nitrite levels, a drop in dissolved oxygen levels due to overcrowding and a lack of aeration/surface agitation, a summertime temperature spike, or some such stressor. The water chemistry in a small, closed-system aquarium can go downhill so quickly and easily. The water quality may have gradually deteriorated in some such respect to the point where it dipped below a critical threshold of some sort and tipped the balance in favor of the pathogens that were present all along. When that happens, the population of opportunistic bacteria can very rapidly get out of control and change from benign to virulent literally like flipping a switch.

Heat stress is a common precursor to many Vibrio infections. For example, here’s what Olin Feuerbacher reports regarding the effect of temperature on bacterial infections. Olin is a marine biologist who is now working as a Molecular Biologist and a member of the research staff at the Arizona Genomics Institute, and who runs a small aquaculture business raising clownfish, gobies, a bit of coral, and all sorts of odd food items including a lots of pods, microalgae, etc. He is also an avid seahorse keeper and has done a lot of research in tropical diseases. He is a grad student working on marine microbiology, mainly ocean borne human pathogens, and his specialty has been the Vibrio bacteria!

In short, Olin really knows his stuff when it comes to this sort of thing. Here are his thoughts on bacterial infections in seahorses:

“They (Vibrio infections) start as a secondary infection after either mechanical damage or parasites or cnidarian stings. Once established, they are difficult to control. This is due in part to the fact that they are typically normal flora in all tanks. They are generally benign until they get an opportunity to invade.”

As for the importance of avoiding heat stress when it comes to bacterial infections (or the value of maintaining reduced temperatures when fighting a bacterial infection), this is what Olin has to say:

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It is interesting that you mentioned the elevated temperatures. I think this is a critical factor in a
number of ways. First, elevated temperatures can have many adverse effects on the immune status of many organisms. Many of the enzymes and proteins involved in an immune response are very temperature sensitive. When studying an outbreak of vibriosis in echinoderms during an El Nino event in the Sea of Cortez, I found that several defensive enzymes in the echinoderms were inactivated by a rise of only a few degrees in water temperature.

In addition to the effects on the hosts, water temperature may have very significant effects on the pathogens as well. First, elevated temperature will obviously increase the rate of microbial growth. Perhaps more importantly, recent research has implicated temperature as a major factor in the regulation of virulence genes. When in the cooler pelagic environment, a bacterium wants to conserve energy, so virulence genes will not be expressed since there is probably no host. However, in warmer temps, these genes can be turned on resulting in pathogenesis.

This is especially true for bacteria such as the Vibrios which exist both as normal aquatic flora and as pathogens in many mammalian species with our nice warm digestive tracts etc. One particularly interesting study showed that the coral pathogen Vibrio strain AK1 was completely benign, despite heavy colonization, in corals at one temp (I forget exactly what, I think it was about 25C), but when temperature was raised by 3 degrees, all of the virulence genes in the Vibrio’s pathogenicity island were turned on. This resulted in severe infection and rapid death of the corals. Bad news for aquarists, but I still think this kind of gene regulation is really cool!
Olin
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Like vibriosis, Lola, mycobacteriosis is another good example of a ubiquitous, widely dispersed disease-causing organism that commonly affects seahorses and other marine fish (and freshwater fish as well). Indeed, mycobacteriosis is one of the rare fish diseases that can also affect humans, who are sometimes infected by working in an aquarium with an active mycobacteria infection, especially if the aquarist happens to have open sores or scrapes on his or her hands.

Mycobacterium is a genus of bacteria that are ubiquitous in almost all environments. Mycobacterium infections occur in many (if not all) vertebrate taxa (e.g., mammals, birds, fish, etc.). Some studies that have looked at prevalence of infection of Mycobacterium in wild animals have often found that a small percentage of wild animals are infected, even without clinical signs.

For example, here is what Kathleen Alford, Curator at the Tennessee Aquarium, has to say about this affliction:

“There are no known treatments for mycobacterium outbreaks. The common thought is that most or all Syngnathids have this even in the wild but can live happily with it under optimum conditions. The best “fix” is to make sure that all parameters are in check: water quality, diet, population density, ect. We have several groups of seahorses that we know have mycobacterium but have been living with it for years. We also have groups of seahorses that have died or are dying off rapidly as the mycobacterium infestation gets worse and worse. Each group is different so my advice is to just make sure that all of your husbandry is optimum and the myco will play out as it will. Good Luck! ”
Sincerely,
Kathlina Alford
Tennessee Aquarium

Mycobacteriosis is commonly known as fish tuberculosis, often shortened to fish TB, or piscine tuberculosis, and is also often called granuloma disease, Here is an excerpt on this affliction from my new book, Lola:

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Cause:

Fish tuberculosis is caused by pathogenic Mycobacteria, of which two different species are the primary culprits: Mycobacterium marinum and Mycobacterium fortuitum (Giwojna, Sep. 2003). Unlike most bacteria the plague fish, these Mycobacteria are gram-positive, and take the form of pleomorphic rods that are acid-fast and nonmotile (Aukes, 2004). When cultured on solid media, they form cream-colored to yellowish colonies (Aukes, 2004).

Mycobacteriosis is worldwide in distribution (Giwojna, Sep. 2003). All fish species are considered susceptible to it (Aukes, 2004). Although this disease can in fact infect almost all fish, certain species are more vulnerable than others (Giwojna, Sep. 2003). The most susceptible species are freshwater tropicals such as black mollies, all gouramis, neons and other tetras, all labyrinth air breathers, and most species of the Carp family (goldfish and koi, for example), Aukes, 2004.

Mycobacteria are ubiquitous and waterborne, and the aquatic environment is considered the disease reservoir for fish tuberculosis (Aukes, 2004). Mycobacterium marinum has been cultured throughout the world from swimming pools, beaches, natural streams, estuaries, lakes, tropical fish tanks, city tap water and well water (Aukes, 2004; Leddo, 2002a). Human epidemics of granulomatous skin disease have occurred from swimming in infected water, and in fact, this mode of human infection is far more common than infection from exposure to infected fish tanks (Aukes, 2004; Giwojna, Sep. 2003).

Mycobacterium, the causative organism, is believed to be ubiquitously present, making it very difficult to eliminate it entirely. However, if good aquarium maintenance and management is followed, including vacuuming of the gravel along with good filtration and regular water changes, combined with a nutritious diet and the addition of an enrichment product rich in vitamins, the problem can be minimized and eliminated as a cause of mortality (Aukes, 2004). Any dead fish should quickly be removed and disposed of properly. Diseased live fish should be isolated and treated in a hospital tank (Giwojna, Sep. 2003).
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So it’s very difficult to determine a proximate cause for any particular infection, Lola, especially when dealing with infections such as vibriosis or mycobacteriosis.

And the same thing is true of Uronema, which is a parasite rather than a type of bacteria. Uronema marinum is the marine equivalent of the Tetrahymena pyriformis parasites that plague freshwater fish (Basleer, 2000). Uronematids are probably the most commonly encountered protozoan parasites of seahorses in the aquarium. They frequently plague wild-caught seahorses and store-bought fish in particular. Unfortunately, they are also one of the deadliest and difficult to eradicate marine parasites.

They live in seawater and normally feed on bacteria and dead tissue, but they are opportunistic invaders that are always on the lookout for food, and are quick to take advantage of weakened fish (Kollman, 2003). It is when conditions favor them and their numbers get out of hand that Uronema becomes a problem. Under those circumstances, they soon begin to attack healthy tissue as well as dead material, invading the gills and muscles, eating red blood cells, and infiltrating the internal organs (Kollman, 2003).

High temperatures and poor water quality are among the environmental factors that favor Uronema. Elevated water temps speed up their life cycle and accelerate the growth rate of Uronematids accordingly (Kollman, 2003).

These ciliated parasites (scuticociliates) are very common on freshly imported wild fishes suffering from shipping stress (Basleer, 2000). Long-distance shipping is one of the factors that commonly contributes to Uronema problems. The deteriorating water quality in the shipping bags of fish transported for 24-48 hours is very conducive to their growth. Low pH, too much ammonia and organic waste, too little dissolved oxygen, and the presence of weakened fish with compromised immune systems all combine to create ideal conditions for these parasites (Basleer, 2000). They feed on damaged tissue, multiply quickly, and invade healthy tissue as their population explodes (Basleer, 2000).

The initial symptoms are excess mucus production, heavy breathing, and loss of color (Basleer, 2000). As the disease progresses, pale patches or bloody sites appear, which become large ulcer-like wounds as the Uronema parasites multiply rapidly and invade the underlying muscle tissue in the advanced stages (Basleer, 2000). Infected fish often scratch these irritated areas. These open bloody lesions are often mistaken for bacterial infections (e.g., marine ulcer disease or “flesh-eating bacteria”), and the affected fish are doomed if antibiotic therapy is administered on the basis of such a misdiagnosis.

So Uronema is a good example the tape of parasites that is ubiquitous and aquariums but causes no problem as long as the aquarium is well-maintained and the water quality is good, and the aquarium fish have healthy immune systems. But the uronematids can quickly get out of hand under unsanitary conditions, deteriorating water quality, or in fishes with impaired immune systems.

And, of course, intestinal flagellates yet another instance of a type of parasite that is a part of the normal intestinal flora in freshwater and marine fish and normally causes no problems. However, when a fish’s immune system is compromised or conditions favor the intestinal flagellates, they can multiply rapidly and quickly get out hand, causing problems for their hosts.

The same thing is true of fungal infections, Lola. Fungal spores are widespread, present everywhere, including our aquariums but our fishy friends normally have no problem with fungus. Fungal infections normally develop at the site of an injury or wound of some sort, and healthy fish otherwise are typically never bothered by fungal problems unless their immune system is suppressed.

Let’s talk for a moment about how many of these ubiquitous disease organisms have become so widespread, Lola. They typically have a very tough, extremely resilient dormant stage, such as a cyst or spore, which is very tiny, invisible to the naked eye, and very difficult to destroy, and which is airborne, carried far and wide on the winds and air currents. When they are carried to a suitable environment, the cysts or spores awaken and develop into the pathogen or parasites in question.

A good example from everyday life is the mold and mildew spores that surround us. They require specific conditions in order to grow and multiply, and earning clean, sanitary, well-maintain home there are typically no problems with mold or mildew, which require a warm, humid warm moist environment in order to thrive. But if the water pipes burst, mold often becomes a problem in the water damaged areas, and if we don’t keep our bathrooms nice and clean and sanitary, mold or mildew might begin to grow on our shower curtains or bathroom tile.

Likewise, if you leave a bowl of fruit out too long, it will spoil and become moldy or overgrown with mildew because the rotting fruit creates favorable conditions for the growth of the ubiquitous spores that have been present all along, but could not gain a foothold when the fruit was fresh and healthy to eat. The mold/mildew spores would only “germinate,” so to speak, grow and spread, when the decaying flesh of the fruit provided them with a perfect culture medium on which to proliferate.

So that’s the situation, Lola. Very likely we will never know specifically what is causing the sporadic infections in your seahorses with no laboratory diagnosis to work with, Lola. The best we can do to run through the factors that are most commonly associated with bacterial infections and discuss some of the things the aquarist can do to help minimize such problems in the future.

As we have been discussing, disease-causing (pathogenic) bacteria are typically 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, such as Mycobacteriosis or popeye.

A bacterial infection almost always indicates that there is another problem that is stressing the fishes and weakening their immune response (Indiviglio, 2002). In addition to treating the infection itself, the hobbyist must also identify and correct the underlying problem in order to restore health. Check your water quality and aquarium parameters. A water change and general clean up are usually a good place to start.

One of the best ways to prevent bacterial infections 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.

When disease breaks out in an established aquarium it is therefore generally an indication that something is amiss with your aquarium conditions. A gradual decline in water quality is often a precursor of disease (Indiviglio, 2002). Poor water quality is stressful to seahorses. Prolonged stress weakens their immune system. And an impaired immune system leaves the seahorse vulnerable to bacterial, parasitic, viral, and fungal infections to which healthy, unstressed seahorses are immune.

I know you’ve probably heard all of this before, Lola, but it’s a difficult, complicated concept to explore. Just remember that it’s quite possible for perfectly healthy seahorse, free of specific pathogens and parasites, to become ill in a healthy aquarium even when it has been exposed to no disease carriers if it is stressed and weakened, or its immune system has otherwise been compromised, because of the ubiquitous, ever-present, ever-opportunistic pathogens and parasites that eventually find their way into our aquariums (indeed, into all aquatic environments), sometimes even arriving airborne.

That being the case, the best way to avoid such problems is to provide our ponies with optimal water quality at all times, a clean, sanitary environment, and a healthy, nutritious diet.

If, in your case, Lola, you’ll believe that these ongoing infections are not harbored within the seahorses themselves, but rather are lurking somewhere within the aquarium environment, then there is one other thing you might consider as a last resort that could be helpful – break down and sterilize your tank, and then start over from scratch.

The best way to sterilize a used aquarium is a three-step procedure, Lola: (1) discard any substrate material and fill the tank with freshwater (ordinary tap water will do nicely), and run it overnight with all the equipment installed and operating; (2) add chlorine bleach to the freshwater, and operate the aquarium for at least several hours with all of the equipment running; and (3) empty the aquarium and air dry it for 24 hours..

The first part is to put the aquarium in place in the desired location and fill it with tap water. Keep all of the equipment on the aquarium running overnight while it is filled with the freshwater right from your tap. (We want the filters and the filter media and the circulation pumps and accessories, even the thermometer to be exposed to the freshwater inside and out for a number of hours, so letting it run overnight is an easy way to accomplish this.) This step will eliminate any sort of parasites that may be present in the aquarium or any of the equipment, Lola, because saltwater parasites cannot survive in pure freshwater for any length of time.

The second step is to add bleach to the freshwater in the seahorse tank, which will sterilize it and kill any of the bacteria, viruses, or fungal spores that may be present in the aquarium. Again, keep all of the equipment running and all of the accessories in the aquariums with the bleach solution for several hours at least so that all the filters and filter media and pumps or powerheads and thermometers, nets, hydrometers, and tubes and all are thoroughly exposed to the bleach inside and out. When this step is completed, the tanks and the equipment will all have been completely sterilized, and you will know that there are no sorts of parasites or pathogens that could have survived the cleansing process.

Sterilize the seahorse tank and all the associated equipment and accessories by using a strong bleach solution for several hours, as explained above, and then drain all the water from the aquarium, and air drying everything completely. Air drying the aquarium and equipment assures that there will be no residual traces of the chlorine bleach left. You can be certain of that by giving the aquarium the “sniff test,” Lola – as long as you can detect no order of chlorine bleach with your nose, the tank will be perfectly safe to set up a new.

The appropriate dosage is 1 cup of chlorine bleach for every 50 gallons of water in the aquarium. Keep the filters running along with all the equipment and accessories in the tank while you treat it with the chlorine bleach so that they are thoroughly exposed to the chlorine as well. Give the chlorine several hours to sterilize everything in the aquarium — nets, accessories and all. After several hours, you can add chlorine neutralizer to your hospital tank to remove the bleach, change out all the water, and rinse everything very thoroughly with freshwater. Keep your fish room well-ventilated while you’re using chlorine bleach and be careful not to breathe in the chlorine fumes when you’re handling the bleach.

Once you had run the aquarium with freshwater and bleach for long enough to be quite sure that any disease organisms had been eradicated, you could use sodium thiosulfate (i.e., a good dechlorinator such as Prime) to pull out the bleach, and add artificial salt mix to achieve the desired salinity/specific gravity. With this method of sterilization, you can keep your skimmer, ultraviolet sterilizer, pumps and powerheads, etc., since all of the equipment gets sterilized thoroughly along with the rest of the tank.

One note of caution: whenever you are using significant amounts of chlorine bleach, it’s very important to work in a well-ventilated area and avoid inhaling the fumes. Also be sure to take whatever precautions are necessary to prevent those fumes from entering any nearby aquaria with live specimens via air pumps.

In short, thoroughly sterilizing a used aquarium is a relatively simple procedure that you can accomplish in one weekend, if you feel it is warranted, Lola.

Good luck.

Respectfully,
Pete Giwojna, Ocean Rider Tech Support