another death

Dear ponydesigns:

While you are treating the surviving female in your hospital tank, now is the time to discuss how to prevent problems with bacterial infections like this in the future, as well as how to handle the aquarium that is harboring a reservoir of infection.

Vibriosis and mycobacteriosis are the two most common bacterial infections of marine fishes we are confronted with as aquarists, and there are acute forms of both those pathogens that can kill their victims quite suddenly, sometimes without any outward symptoms at all. (Due to their sedentary lifestyle, tendency to change coloration, and armor-plated exoskeletons, seahorses are good at concealing their ailments until they have become quite advanced. Lethargy and inactivity may be difficult to pick up on with ambush predators that aren’t active swimmers to begin with, and it can be equally difficult to tell whether a change in coloration is normal with seahorses or an indication that they have a problem or that conditions are not to their liking.)

With gas bubble disease (GBD), it is not normal for the affected seahorse to go from healthy to deathly ill in a short period of time. Seahorses can often survive for a number of weeks with subcutaneous emphysema, recurring pouch emphysema and hyperinflation of the swimbladder. Internal GBD is typically far advanced before any obvious symptoms are seen, such as positive buoyancy or severe swelling and bloating of the coelomic cavity. Even without treatment, seahorses with GBD can linger for a long time before they finally succumb, and it is often secondary infections that take hold in their weakened condition which are ultimately the cause of death. An exception would be if an intravascular gas embolism migrated from its birth site via the circulatory system, lodged in a vital organ, and grew large enough to occlude the blood flow or put pressure on vital nerves. But that’s something that rarely occurs without their being outward signs of GBD at work elsewhere in the body.

So it’s clear to me that your seahorse developed a virulent bacterial infection of some kind, secondary to any problems with GBD they may have experienced, ponydesigns. As to what caused the infection, it could be anything that impaired the immune system of the seahorse or suppressed its immune response, leaving it vulnerable to disease. In the aquarium, this is usually some form of stress, so I’m going to run through the usual aquarium stressors with you that are often associated with disease outbreaks:

Disease-causing (pathogenic) bacteria 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, 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, viral, and fungal infections to which healthy, unstressed seahorses are immune. As if that weren’t bad enough, there are a number of environmental diseases that are caused directly by water quality problems.

With this in mind, it’s important to review the most common stressors of captive seahorses. These include the design of the aquarium itself. A poorly designed seahorse setup that lacks adequate cover and shelter, or has too few hitching posts, will be stressful to the occupants (Topps, 1999). Seahorses are shy, secretive animals that rely on camouflage and the ability to conceal themselves for their safety and survival. A sparsely decorated tank that leaves them feeling vulnerable and exposed will be a source of constant stress (Topps, 1999). The seahorse setup should have plenty of secure hiding places so they can conceal themselves from view completely whenever they feel the need for privacy. It should be located in a low traffic area away from external sources of shock and vibration.

Needless to say, rapid fluctuations in temperature, pH, salinity and other aquarium parameters must also be avoided. A large aquarium of 40 gallons or more provides much greater stability in that regard than does a smaller setup. The greater the water volume in the aquarium and sump, the more stable the system will be.

Heat stress 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.

In short, it’s doubly important to keep seahorses at the proper temperature. Because of the reasons mentioned above and the fact that water holds less and less dissolved oxygen as it warms up, seahorses generally tolerate temps at the lower end of their preferred range much better than they handle temperatures at the upper limit of their range.

Incompatible tankmates are also stressful for seahorses. This includes not only aggressive, territorial fishes and potential predators but also inoffensive species that are restless, active fishes. Seahorses may be uneasy around fishes that are always on the go, swimming tirelessly back and forth.

Other common stressors for seahorses include overcrowding, overfeeding, stray voltage, and a host of issues related to water quality: ammonia or nitrite spikes, high nitrate levels, inadequate circulation and oxygenation, high CO2 levels and low 02 levels, low pH, etc., etc., etc (Giwojna, Jun. 2002).

In short, if hobbyists provide their seahorses with a stress-free environment, optimum water quality, and a nutritious diet, they will thrive and your aquarium will flourish with a minimum of problems. Preventing disease in the first place is infinitely preferable to trying to treat health problems after the fact.

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, viral, and fungal infections to which healthy, unstressed seahorses are immune.

At the first sign of a health problem:

Because diseases are so often directly related to water quality, or due to stress resulting from a decline in water quality, when trouble arises the first thing you should do is to break out your test kits and check your water chemistry. Very often that will provide a clue to the problem. Make sure the aquarium temperature is within the acceptable range and check for ammonia and/or nitrite spikes first. See if your nitrate levels have risen to harmful levels and look for a drop in pH.

Be sure to check your dissolved oxygen (O2) level too. A significant drop in O2 levels (6 – 7 ppm is optimal) is very stressful yet easily corrected by increasing surface agitation and circulation to promote better oxygenation and gas exchange. At the other extreme, oxygen supersaturation is a red flag indicating a potentially deadly problem with gas embolisms (Gas Bubble Syndrome).

If any of your water quality parameters are off significantly, that may well be the cause of the problem or at least the source of the stress that weakened your seahorses and made them susceptible to disease. And correcting your water chemistry may well nip the problem in the bud, particularly if it is environmental, without the need for any further treatment.

Clean Up & Perform a Water Change

After a quick check of the water chemistry to assess the situation, it’s time to change water and clean up. In most cases, the surest way to improve your water quality and correct the water chemistry is to combine a 25%-50% water change with a thorough aquarium clean up. Siphon around the base of your rockwork and decorations, vacuum the top 1/2 inch of the sand or gravel, rinse or replace your prefilter, and administer a general system cleaning. The idea is to remove any accumulated excess organic material in the sand/gravel bed, top of the filter, or tank that could degrade your water quality, serve as a breeding ground for bacteria or a reservoir for disease, or otherwise be stressing your seahorses. [Note: when cleaning the filter, your goal is to remove excess organic wastes WITHOUT disturbing the balance of the nitrifying bacteria. Do not dismantle the entire filter, overhaul your entire filter system in one fell swoop, or clean your primary filtration system too zealously or you may impair your biological filtration.]

At first glance your aquarium parameters may look great, but there are some water quality issues that are difficult to detect with standard tests, such as a decrease in dissolved 02, transitory ammonia/nitrite spikes following a heavy feeding, pH drift, or the gradual accumulation of detritus. A water change and cleanup is a simple preventative measure that can help defuse those kinds of hidden factors before they become a problem and stress out your seahorses. These simple measures may restore your water quality and correct the source of the stress before your seahorse becomes seriously ill and requires treatment.

In your case, ponydesigns, I suspect that the infectious disease that ravaged your seahorses was due to Vibrio or Pseudomonas bacteria, which are highly infectious and very difficult to eradicate from an aquarium. Under the circumstances, it would be appropriate to break down your main tank, sterilize everything, and start over from scratch. Since you have had an outbreak of a highly contagious infection that was transmitted from one seahorse to the next and killed quite quickly, often before there was even time to attempt to treat the affected seahorse once it begins showing symptoms of a problem, I think it would be prudent to sterilize the tank and all of the equipment in it, and then recycle the aquarium from scratch again before you consider keeping any new fish in the aquarium. And I would be very careful not to spread the infection from the contaminated tank to any of your other aquariums.

Do NOT disperse your live rock, substratum, macroalgae, equipment or accessories from the infected tank to your other aquaria, or you risk inoculating them with Vibrio/Pseudomonas and spreading this virulent infection to all your tanks! And you must be extremely careful to avoid accidentally cross-contaminating your other tanks from your infected seahorse tank. Any nets, hydrometers, or other equipment used in your seahorse tank should be sterilized after every use and not placed into or used in any other tanks. Avoid working in your seahorse tank or your hospital tank with your bare hands, scrub/disinfect your hands and arms thoroughly after working on your seahorse tank, and do not place your hands in the seahorse tank and then place your hands in another aquarium. These bacteria can even be transferred from one aquarium to another by splashing water droplets or as an aerosol via the mist generated from a protein skimmer or an airstone. Be careful!

Sterilize the seahorse tank and all the equipment it contains by using a strong bleach solution and then air drying it completely. To be on the safe side I would discard the live sand or gravel substrate and any macroalgae in the aquarium, but you can attempt to recycle the live rock by sterilizing it, converting it to dead rock, reseeding it with beneficial bacteria, and then allowing it to be slowly recolonized by healthy sessile life. Once the rock has been sufficiently sterilized, it can be placed in a sump or back in the main tank to regain its bacteria bed and time will do the rest.

Here is the method that Paul Anderson (Department of Fisheries and Aquatic Sciences, University of Florida) recommends for sterilizing systems with stubborn Mycobacteria infections (mycobacteriosis is another very stubborn infection that is contagious and difficult to eradicate):

"Effective disinfectants against mycobacterium include spraying with 70% Ethanol and allowing the equipment to air-dry, and bleach baths (I use 50ppm bleach baths with a minimum contact time of one hour, this has been reported to be effective against M. marinum) followed by sodium thiosulfate neutralization baths. Ultraviolet light sterilization is also recommended in myco-positive systems. If you’ve got myco-positive tanks among other systems, common sense suggests performing husbandry on these systems last in your rounds.

"A note on ethanol: I have found in my experience that seahorses are very sensitive to ethanol, so I advise being very cautious to avoid overspray into adjacent tanks (Paul Anderson, pers. com.)."

So if you want to be really sure you are eradicating any disease organisms in your seahorse tank, ponydesigns, you might first disinfect the affected tank and all of its equipment with 70% ethanol, allow it to air dry, and then set it up anew and fill it with freshwater, start everything operating again, and administer a good stiff dose of chlorine bleach for as long as it takes for you to feel confident of the results. That will assure that the bleach solution is circulated throughout your protein skimmer, filters, and all the other equipment, thus sterilizing them early both inside and out. I can’t imagine any marine pathogens or parasites that could survive the ethanol disinfection process, followed by prolonged immersion in freshwater treated with an effective dose of beach.

The appropriate dosage is 1 cup of chlorine bleach for every 50 gallons of water in the aquarium. Keep the filters running on the hospital tank while you treat it with the chlorine bleach so that they are thoroughly exposed to the chlorine as well. Give the chlorine about two days to sterilize everything in the aquarium — nets, accessories and all. After 48 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 treating the hospital tank with the 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 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.

And, as Dr. Anderson noted, when you’ve had a disease outbreak that warrants breaking down and sterilizing the system, it’s a good idea to install and maintain UV sterilization on that tank in the future when it’s up and running again.

The best way to sterilize the live rock is often to remove it from the aquarium, place it in a large container of water, and boil it thoroughly. The boiling water will effectively sterilize and purify the live rock, which is then safe to use again after it has been air dried. (Sometimes aquarists will sterilize the live rock by soaking it in a strong solution of bleach or vinegar, but sometimes the bleach or vinegar will soak deep into the porous interior of the live rock and be leached out of it gradually for a long time thereafter, so it can be difficult to remove all traces of the bleach or vinegar before its placed back into the aquarium. For this reason, boiling the live rock is often a safer way to sterilize.

Once the aquarium and all of the associated equipment and accessories have been sterilized, and the aquarium has been refill with saltwater adjusted to the proper pH and salinity, you can place new live sand in the aquarium, which will reseed the tank with beneficial nitrifying bacteria, and then place the sterilized live rock back in the aquarium and cycle the entire tank anew. The cycling process is exactly the same as when you set up a brand-new aquarium, and the beneficial Nitrobacter and Nitrosomonas bacteria will recolonized the live rock during the cycling process.

If you don’t like to use live sand in your seahorse tank for any reason, teacher, then you can simply add a little BioSpira to seed the aquarium and live rock with beneficial bacteria instead. Bio-Spira is a product offered by Marineland which contains the live bacteria necessary to convert ammonia and nitrite into harmless nitrate. It is available for both freshwater and marine aquariums, so of course be sure to get the Bio-Spira for saltwater. Just use it as explained below and it will help your aquarium to recycle more quickly:

IMPORTANT:
BIO-Spira is a "live" bacteria culture that is sold refrigerated and must be kept refrigerated until used. It can not be overdosed. Repeated dosing of your aquarium with ammonia removing liquids (such as BIO-Safe, Amquel, Ammo-lock and Aqua-Safe) can inhibit the beneficial action of BIO-Spira. Ammonia removing liquids should only be used to initially treat tap water. It is normal to have a small (<2 ppm) amount of ammonia or nitrate during the first few days after set-up. These concentrations are not harmful and will quickly drop to zero with proper use of BIO-Spira.

DIRECTIONS FOR USE:
Shake well before each use. Use 1 ounce (29.6 ml) of BIO-Spira per 30 gallons of water. BIO-Spira cannot be overdosed. Keep refrigerated. Be sure to shut off any UV sterilizers and remove medication by means of a water change or activated carbon.

There is a slight chance that the cleanup crew and invertebrates could also be harboring some of the harmful bacteria and act as a disease reservoir, but it’s fairly unlikely. For one thing, invertebrates in general are not susceptible to the same pathogens and parasites that plague seahorses and other marine fishes (i.e., vertebrates). If they were carrying any of the parasites that could bother seahorses, it would be as hitchhikers, and that’s unlikely because those same parasites normally cannot survive long without a suitable fish host.

Secondly, snails and invertebrates in general cannot tolerate the usual prophylactic measures we apply to marine fishes when we quarentine them or treat them prophylactically. For example, neither shrimp nor many types of snails can withstand hyposalinity let alone a freshwater dip. Nor do they tolerate the usual chemi-therapeutic agents we normally use to cleanse quarantined fish of parasites, such as formalin, malachite green, copper sulfate, dylox, Panacur, praziquantel, Parinox, metronidazole, etc.. So there is nothing that you could treat your aquarium janitors with to eradicate any pathogens or parasites they could be carrying that would not also kill your sanitation engineers in the process.

In short, you basically have three choices regarding the decorative shrimp, snails, and micro hermits from the cleanup crew in the infected aquarium. First of all, you can destroy them and be 100% certain they will not reintroduce any disease organisms to the aquarium after it has been sterilized. That is the safest and surest method of dealing with the invertebrates from the contaminated tank, and is not too great of a sacrifice when it is only snails or microhermit crabs that are being euthanized and discard, since they can be replaced fairly inexpensively. But with the decorative shrimp shrimp and live corals, I can certainly understand that that may not be an especially attractive option.

Secondly, if you have a dedicated invertebrate tank that houses no fish, you could consider relocating the cleanup crew from the infected aquarium to the invertebrate tank. Any bacteria or pathogens they are carrying should not cause any problems in the tank that just contains other invertebrates, since they are only pathogenic when they have a vertebrate host to infect. That’s a possibility but one I would not pursue, since you risk spreading the infectious organisms to another tank…

Thirdly, you could quarantine the cleanup crew from the infected aquarium for a period of six weeks while your seahorse tank was being sterilized and recycled. Any parasites the invertebrates from the cleanup crew could possibly have been carrying that could pose a risk to the seahorses would require a vertebrate host in order to survive, and after six weeks without any fish in the aquarium, any such parasites should have been eliminated and are no longer a cause for concern. (Obligate parasites cannot survive an extended period of time without a suitable vertebrate host.) So after the the invertebrates have been isolated for six weeks, they could be returned to the sterilized and recycled main tank with little risk of introducing anything harmful. You could not be 100% certain with this method, but the risk would be slight.

In short, I would suggest breaking down your seahorse tank, discarding the substrate, boiling the live rock so it can be reused, and then sterilizing the aquarium and cycling at all over again from scratch, ponydesigns.

Respectfully,
Pete Giwojna