- This topic has 4 replies, 3 voices, and was last updated 16 years, 8 months ago by Pete Giwojna.
March 3, 2007 at 8:16 am #1148flyinglantisMember
One of my male seahorses has a stuck trigger. Is there any \"cure\" for this? Is it detrimental to the seahorse\’s survival? I tried searching the internet for any information but all I could seem to find was a description of what it was and a few pictures.
Any info would be much appreciated.
HowardMarch 4, 2007 at 12:29 am #3469Pete GiwojnaGuest
Weak snick, sticky trigger, and trigger lock are a group of related feeding disorders that are usually due to either a mechanical injury or an infection affecting the seahorse’s hyoid bone trigger mechanism or the underlying musculature with which it generates the powerful suction that it uses when feeding. Such mechanical injuries can sometimes be caused by ingesting a foreign object while feeding, or the problem may be due to protozoan parasites that attack the gills and eventually affect the muscles that operate the buccal suction pump and/or the opercular suction pumps or the hyoid bone trigger mechanism itself.
A problem with sticky trigger or trigger lock is harmful when it is severe enough to keep the seahorse from feeding properly. When the problem is due to a mechanical injury or muscular strain, the injury will often heal itself without any intervention from the hobbyist and treatment consists of providing softbodied prey that are easy for the seahorse to swallow while the healing takes place. When protozoan parasites and/or secondary infections of the trigger mechanism and underlying musculature are involved, a freshwater dip can be a useful first aid measure and treatment with antiparasitics and/or antibiotics may be advisable.
Here’s an excerpt on sticky trigger/trigger lock from my new book (Complete Guide to Greater Seahorses in the Aquarium, unpublished) that discusses such feeding disorders in greater detail:
FEEDING DIFFICULTIES: WEAK SNICK, TRIGGER LOCK, & LOCK JAW
Seahorses suck! That’s a fact. Our amazing aquatic equines are supremely well adapted for suctorial feeding, which just means that their tubular snouts are designed for generating a powerful suction and slurping up small prey whole (Giwojna, Feb. 2004). Basically, their tubular mouths operate like slurp guns, a method of feeding that is often adopted by fish accustomed to taking prey from the bottom or plucking small crustaceans and larvae from the leaves of underwater plants (Evans, 1998). The anatomy of the seahorse’s head has evolved to accommodate this method of feeding (Giwojna, Feb. 2004).
For example, a tubular mouth is an advantage for suctorial feeding because it acts like a pipette and the narrow opening accelerates the inrush of water via the Venturi effect, thus maximizing the suction generated by the powerful head muscles (Giwojna, Feb. 2004). The seahorse’s oral or buccal cavity and gill chambers (opercular cavities) act as dual suction pumps that draw the water inwards with considerable force (Evans, 1998). Expansion of the buccal and opercular cavities causes a sudden drop in pressure within the mouth (Evans, 1998). The suction thus created allows the seahorse to suck up food through its slurp-gun snout faster than the eye can follow. In essence, the seahorse inhales its food in the blink of an eye, and cavitation caused by the sudden inrush of water traveling at tremendous velocity through the narrow snout and characteristic movements of its head and skull bones produce the distinctly audible "snick!" which announces the demise of its prey (Giwojna, Feb. 2004).
Every seahorse keeper is familiar with the seahorse’s "trigger," located at the underside of its jaws at the base of its throat, which moves downward sharply when the seahorse strikes, thereby expanding its oral (buccal) cavity and generating the suction to draw its prey inwards. This trigger is actually the seahorse’s hyoid bone, and it is pulled downward by contraction of the powerful sternohyoideus muscle that runs from the hyoid bone to the cleithrum (one of the bones of the pectoral girdle), which forms part of the seahorse’s bony exoskeleton (the cleithral ring) just behind its head (Evans, 1998).
The suction generated by the sudden downward contraction of the hyoid bone when a feeding seahorse "pulls the trigger" on its intended prey is greatly enhanced by the nearly simultaneous expansion of its gill chambers or opercular cavities (Giwojna, Feb. 2004). The additional suction thus created by the seahorse’s opercular pump is produced by contractions of the hyohyoideus muscles and dilator operculi muscles (Evans, 1998). The water pulled into the gill chambers this way is then expelled from the opercular cavity through a small pore. (This narrow opening accelerates the stream of water passing through it in the same way as its narrow tubular snout does.) The seahorse’s bony coronet evolved atop its head in part to provide solid anchorage and attachment points for the large muscles that operate its buccal suction pump and twin opercular suction pumps, which enable it to feed so efficiently (Giwojna, Feb. 2004). This is the perfect feeding mechanism for an ambush predators, and the seahorse is perfectly adapted for its role as the sniper of the seagrass jungle (Giwojna, Feb. 2004).
Of course the seahorse’s turreted, independently operating eyes are the perfect targeting system for this sophisticated feeding apparatus (Giwojna, Feb. 2004). Side-mounted, hemispherical eye turrets provide nearly 360 degrees of vision and allow the seahorse to look upwards and downwards (or forward and backwards) simultaneously in search of potential prey or possible predators (Giwojna, Feb. 2004). As soon as it detects a likely prey item, both eyes lock on it simultaneously and track it intently, thus providing excellent depth perception. This allows the seahorse to judge distances with remarkable accuracy as it draws a bead on its intended victim (Giwojna, Feb. 2004).
The hyoid bone is the trigger which fires the seahorse’s slurp-gun snout, and the moment its prey closes within striking distance, the powerful sternohyoideus muscle contracts and pull the trigger (Giwojna, Feb. 2004). The buccal cavity expands, followed the almost instantaneous contraction of the hyohyoideus muscles and dilator operculi muscles, which likewise expand the opercular cavities (Evans, 1998). The resulting drop in pressure creates a sharp inrush of water, which draws the prey irresistibly into the seahorse’s mouth (Evans, 1998). Once the prey has been sucked in, the mouth is closed. At this point, the buccal and opercular cavities are contracted and the excess water is forced out in a strong stream via the tiny opercular pores (Evans, 1998).
All this happens in an instant, faster than the eye can follow, and the powerful suction that is generated often macerates large prey (Giwojna, Feb. 2004). When the resulting debris is expelled from the gill chambers, it looks remarkably as if the seahorse is shooting smoke out of its ears, thus giving a feeding seahorse an uncanny resemblance to the legendary fire-breathing dragon (Giwojna, Feb. 2004).
However, when this remarkable feeding mechanism is injured or disrupted by parasites and/or secondary infections, a number of problems arise. Weak snick is an unusual affliction that results when a seahorse is unable to generate adequate suction to feed properly. Seahorses develop weak snick when their sophisticated feeding apparatus, or the muscles that operate it, are incapacitated as a result of injury or infection.
For example, I have often seen it in seahorses as a result of protozoan parasite infections (Amyloodinium, Cryptocaryon, Brooklynella, Uronema, etc.). I tend to suspect that’s the cause when the weak snick is accompanied by rapid respiration and labored breathing, or when more that one seahorse develops the condition, or when the weak snick victim’s tankmates are bothered by odd ailments such as "trigger lock," appetite loss, lockjaw, heavy breathing, or the first signs of snout rot, which all early indications of masked protozoan parasite infections (Giwojna, Dec. 2003). These organisms typically attack the gills first, from which they spread to the throat and mouth (oral or buccal cavity). As their numbers build up in the gills and they spread from within, invading the esophagus and oral cavity, symptoms such as rapid breathing, loss of appetite, weak snick, trigger lock, and snout rot begin to appear (Giwojna, Dec. 2003).
This is how I believe the disease progresses in such cases: the burrowing of the embedded parasites causes hyperplasia of the underlying tissue, and when sufficient numbers of them build up in the gills, we see the initial symptoms of respiratory distress, labored breathing, and huffing (Giwojna, Dec. 2003). During a heavy infestation, the parasites may attack the key muscles that expand the opercular cavity, or sheer numbers of the parasites can clog the gills to the extent that the opercular pump is impaired, resulting in weak snick due to a decrease in suction (Giwojna, Dec. 2003). In severe cases, this will eventually result in death by asphyxiation.
In less severe cases, the parasites will continue to spread from the gills into the throat, buccal cavity, and eventually the snout itself (Giwojna, Dec. 2003). When this happens, the irritation caused by the burrowing parasites and the hyperplasia of the infected tissue can cause loss of appetite or difficulty swallowing and the victim may go on a hunger strike (Giwojna, Dec. 2003). If the swelling and hyperplasia occlude the gills, throat and snout sufficiently to prevent the seahorse from generating adequate suction when attempting to feed, weak snick is the result (Giwojna, Dec. 2003). If the burrowing of the embedded parasites allows secondary fungal or bacterial infections to take hold, the seahorse can develop snout rot (Giwojna, Dec. 2003). When such secondary infection(s) affect the sternohyoideus muscle that controls the hyoid bone trigger mechanism, ailments such trigger lock, sticky trigger, or lockjaw result and again the seahorse is unable to feed (Giwojna, Dec. 2003). Weak snick can be caused in this way as well if the sternohyoideus muscle is affected to the extent that hyoid trigger still operates, but so feebly that the buccal pump can no longer generate sufficient suction to feed (Giwojna, Dec. 2003).
Another common cause of weak snick in many instances is a mechanical injury to the seahorse’s hyoid-bone "trigger" mechanism. This sometimes happens when a seahorse accidentally ingests a foreign object when feeding off the bottom. The offending particle is often a piece of gravel or crushed shell. When a hard, sizable foreign object such as this is ingested, it can lodge in the throat or snout, and the seahorse may have difficulty expelling it again. (The seahorse’s feeding mechanism is much better suited for sucking things in than spitting them out again.) When that happens, the seahorse is almost always able to clear the offending object eventually, but sometimes not before it causes considerable irritation or the repeated efforts to eject it cause a muscular strain to the hyoid trigger mechanism. The seahorse then acts as though it has a very bad sore throat. The suction it generates is weak and both the act of pulling the trigger and the act of swallowing appear to be painful. The seahorse feeds reluctantly or halfheartedly as a result, and may eventually stop feeding altogether. Such mechanical injuries can also open the door for snout rot.
Suspect a mechanical injury when the weak snick or sticky trigger is not accompanied by respiratory distress, when only one of your seahorses is affected and exhibiting unusual symptoms, or when you witnessed the seahorse struggling to expel a foreign object. In such cases, most often the problem clears up on its own after two weeks to two months as the injury heals. No treatment is necessary and the key to a successful outcome is keeping the patient eating while the healing takes place. That’s what treatment should concentrate on.
When these feeding difficulties arise, it’s a good idea to try tempting the affected seahorse with live adult brine shrimp. Seahorses suffering from weak snick induced by an injury may have better luck slurping up smaller, lighter, soft-bodied prey like brine shrimp; if so, that will be enough to keep them going while they heal. You’ll want to enrich the brine shrimp to maximize its nutritional value, and gutloading the shrimp with an enrichment product high in HUFA such as Vibrance is a good way to fortify it beforehand. Brine shrimp are filter feeders that will ingest whatever is suspended in the water with them, so all you need to do is add a pinch or two (or drop or two) of the enrichment formula to a small container of saltwater swarming with brine shrimp at least 30 minutes before you offer the shrimp to your seahorse.
In short, Howard, if the seahorse is experiencing respiratory distress or any other indications that suggest the problem could be due to protozoan parasites, there are number of treatment options you can consider.
For example, in that case, you could treat your seahorse with a 10-minute freshwater dip and/or a 30-60 minute bath in formalin. Both those procedures are very effective in eliminating ectoparasites and gill parasites, and may provide your seahorse with immediate relief. Or you could treat the main tank with hyposalinity or Parinox, depending on whether or not it houses any senstive invertebrates. Or you could try treating your seahorse in a hospital tank using acriflavine in conjunction with methylene blue. I will be happy to provide you with instructions for all of these treatment options in case you feel such a procedure or procedures is warranted in your case.
If you don’t have a clear idea whether the male’s sticky trigger is due to an injury or to an infection brought on by gill parasites, you might try administering a diagnostic 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). Regardless of how you detoxify the freshwater for the dip, it’s important to aerate the water in the dipping container well beforehand to increase the level of dissolved oxygen in the water. Many hobbyists leave the airstone in the dipping container throughout the procedure.
Adjusting the pH of the water in the dipping container so that it matches the pH of the water in the aquarium is a crucial step. If there is too much of a difference in the pH, there is a possibility the seahorse could go into shock during the dipping procedure. Preadjusting the pH will prevent that from happening. If you will are unsure about your ability to accurately adjust the pH in the dipping container, avoid this procedure altogether or be prepared to monitor the seahorse very carefully and shorten the duration of the tip to no more than about 4 minutes.
Observe the horse closely during the dip. You may see some immediate signs of distress or shock. Sometimes the horse will immediately lie on its side on the bottom. That’s a fairly common reaction — normal and to be expected, rather than a cause for concern, so don’t be alarmed if this happens. Just nudge or tap the seahorse gently with your finger if it lies down on its side. Normally, the seahorse will respond to the slight nudge by righting itself again and calm down for the duration of the dip. However, if it does not respond, stop the treatment.
Most seahorses tolerate the treatment well and experience no problems, but if you see continued signs of distress — twitching, thrashing around etc. — stop the treatment.
After you have completed the dip and returned the seahorses to the aquarium, save the dip water and examined it closely for any sign of parasites. The change in osmotic pressure from saltwater to freshwater will cause ectoparasites to lyse (i.e., swell and burst) or drop off their host after 7-10 minutes, and they will be left behind in the dipping water. Protozoan parasites are microscopic and won’t be visible to the naked eye, but some of the other ectoparasites can be clearly seen. For example, monogenetic trematodes will appear as opaque sesame seeds drifting in the water (Giwojna, Aug. 2003) and nematodes may be visible as tiny hairlike worms 1/16-3/16 of an inch long. Other parasites may appear as tiny dots in the water. Freshwater dips can thus often provide affected seahorses with some immediate relief by ridding them of these irritating pests and can also aid their breathing by flushing out gill parasites.
Okay, Howard, that’s the quick rundown on sticky trigger and related feeding problems. Let me know whether you feel the problem is most likely due to a mechanical injury/muscular strain or is more likely due to parasites and/or a secondary infection affecting the hyoid bone trigger mechanism, and I can advise you regarding possible treatment options in more detail, sir.
If your seahorse is still able to eat normally despite its stuck trigger, you can concentrate on providing optimum water quality and keeping the seahorse eating, using softbodied adult Artemia if necessary, and see if the condition resolves itself. But if the problem worsens and interferes with his ability to eat, you will need to consider providing some form of treatment to provide some relief for the seahorse.
Best of luck resolving this problem, Howard! Here’s hoping it’s simply a muscular strain that heals up on its own with no complications whatsoever.
Pete GiwojnaMarch 4, 2007 at 1:11 am #3470flyinglantisGuest
Thanks for the detailed response, Pete.
My male is still able to eat, in fact he is usually the first one at the feeding station, but I don’t think he’s getting his fill. His belly never gets as big and robust looking as the others when he’s done feeding. I’ll see about getting some brine shrimp for him to eat. I haven’t seen him breathing heavily/rapidly so I don’t think there’s a parasite infection. The other three seahorses seem to be doing fine. I have seen this particular male poking around at the gravel in the past, so maybe he did accidentally suck up something he shouldn’t have. If I start to see any other signs of distress I’ll try the freshwater dip, but for now I’ll just keep an eye on him and the others.
HowardJune 19, 2007 at 7:53 am #3696Saint2966Guest
Well I got to the bottom of the last "Tank Raised" horses I purchased. The company finally requested more info from their supplier and found that my new additions (4) were in fact Net Pinned. They have since deceased along with two mustangs, One Sunburst, and One Northern Erectus juvenile. I am now down to 3 Sunbursts, 4 juvenile erectus and the barbouri couple. I have had no losses in two weeks. Water perameters are good (nitrates still high). I have done two 25% water changes since the last loss. This morning I noticed the male Barbouri with GBD. Tonight I began diamox treatments only to find he could not snick the loaded mysis. I found this in the search and I am now really worried. What is the most likely parasite invasion the newcomers could have brought in? I have fresh water dipped Pegasus and placed him in the horspital tank with Triple sulfa, and Methelene Blue. I added his live brine shrimp in hopes that he could snick something. If you can remember I have a 120 Gallon with trickle filter and sump system. My biological filtration is excellent and I have a trillion copepods, anthropods and spaghetti worms on duty at all times. I have incorporated peppermint shrimp, snails and micro stars for cleaning crew. I am sure that this tank is now loaded with parasites. How do I treat the main tank without losing all occupants? If I removed all the corals (alot of them), and the remaining nine horses. I still have to be concerned about killing off cleaning crews and bioload? HELP!!!
PLEASE ADVISE ALL NET PINNED IS NOT TANK RAISED and one week quarantine will not reveal parasites.
THANKS AGAIN CINDYJune 20, 2007 at 2:03 am #3700Pete GiwojnaGuest
Ugh — that sounds like an ugly situation! I’m very sorry to hear about the problems the pen-raised ponies may have introduced to your outstanding seahorse tank.
You’re right about the net-penned seahorses, Cindy, and it’s unfortunate that you didn’t know the true origin of the suspect ponies from the beginning so that you could have taken the appropriate precautions. Nowadays everyone is aware that cultured or domesticated seahorses are far superior to wild caught specimens. Selecting suitable seahorses therefore seems like it should be a simple, straightforward proposition — avoid wild-caught specimens and stick with cultured seahorses, and you can’t go wrong. In actual practice, when you go shopping for seahorses you will see them described as everything from CB (i.e., captive bred) to TB (tank bred) to CR (captive raised) to TR (tank-raised) to WC (wild-caught) as well as a number of other acronyms, and it will quickly become apparent that not all domesticated seahorses are created equal. There is a world of difference between seahorses that are captive bred, captive raised, or pen-raised. Trying to sort through this alphabet soup can quickly become quite confusing, so the first thing we need to do is to clarify the terminology.
The designation CB indicates seahorses that are captive bred and raised, meaning their parents are cultured seahorses that were selectively bred at an aquaculture facility specifically for the pet trade and the offspring from that pairing were raised by hand in rearing tanks using state-of-the-art grow-out and maturation protocols and technologies. In my opinion, these are the best animals for the hobbyist because they have been born and bred for aquarium conditions for a number of generations and are hardy, highly adaptable seahorses with superior disease resistance. They will have been trained to eat frozen Mysis as their staple, everyday diet from a very tender age, making them much easier to feed and care for then wild-caught seahorses, pen-raised ponies, or tank-raised seahorses. Because they are reared by hand, they are accustomed to the human presence and quickly come to recognize their keepers as the givers of gourmet delights, becoming real pets in every sense of the word. And because each cohort is raised in close proximity with many other seahorses of similar size and age, they are highly gregarious, social animals that very much appreciate the company of others of their kind.
The acronyms CB (i.e., captive bred) and TB (i.e., tank bred) are designations that are used pretty much interchangeably by hobbyists and the aquarium industry alike, but you still have to be wary because to my knowledge there are still no official standards or formally recognized nomenclature within the industry regarding these matters. Captive bred or tank bred specimens are the most desirable of the domesticated seahorses.
On the other hand, tank-raised (TR) and captive-raised (CR) seahorses can be very problematic. With regard to seahorses, the tank-raised or captive raised designation generally indicates that the parents are wild seahorses; rather than having paired up and bred in the aquarium, tank-raised seahorses are generally the offspring of a gravid male removed from the wild. Once he gives birth, his brood is raised in captivity as usual, but of course his progeny have the same genotype or genetic makeup as wild seahorses, and are therefore no more accustomed to life in the aquarium than seahorses collected from the wild. As a result, they may have difficulty adjusting to aquarium conditions and frozen foods, and they will not have the same disease resistance as seahorses that have been captive-bred-and-raised for many generations. For these reasons, it is best to avoid seahorses that have merely been tank-raised or captive raised and look for livestock that is captive bred or tank bred instead.
Further complicating the situation is the advent of seahorses that have been "pen-raised" in the open sea under less than desirable circumstances, and which are now reaching the market in the United States in large numbers. Net pens are a low-tech, low-maintenance method of farming seahorses that basically involves raising them in large enclosures in coastal waters. It is a common practice in Indonesia, many Asian countries, and the Philippines. In some cases, entire lagoons may be fenced off for that purpose. In the simplest form of pen rearing, broodstock are released into these enclosures, and then they and their progeny are pretty much allowed to fend for themselves thereafter. Any offspring that survive to marketable size are periodically harvested from the holding pens or lagoons.
Such operations are controversial with environmentalists for a number of reasons. Since the enclosures are open to the ocean, there is a real risk that adults or their fry may escape from the pens and establish colonies in the wild that may pose a threat to endemic seahorse populations. The pens are no barrier to disease organisms or parasites, so pathogens and parasites imported on foreign broodstock may spread to fishes in the wild (or vice versa). Wastes from the high density of penned animals are carried directly to ocean on prevailing tides and currents and may have a negative environmental impact on the surrounding area. There is no way to monitor the penned animals, hence no way to determine whether the seahorses they contain are actually born and raised in the enclosures or are merely wild-caught seahorses maintained in holding pens prior to being shipped off to unsuspecting consumers.
Pen-grown ponies can thus be risky for the hobbyist because of the circumstances under which they were raised. In essence, a mesh barrier is all that separates them from wild seahorses. There is no guarantee they will be disease free. Although many of them learn to accept frozen Mysis, there is no guarantee they will eat frozen foods since they are often accustomed to foraging for live prey. There is no guarantee they will be able to adjust to aquarium conditions since they are essentially raised in the sea. There is no guarantee that they are even captive bred, since the pens are not secure and livestock is introduced and removed from the pens and lagoons on a continuous basis. There is no guarantee they will be friendly and sociable rather than shying away from their keepers, since they are unaccustomed to the human presence. Pen-raised ponies are particularly misleading because they are almost never advertised as such — they are typically called captive raised or even captive bred seahorses, which can lead the unwary consumer to assume that they have been painstakingly raised using intensive mariculture techniques and rearing protocols. Nothing could be further from the truth.
Pen-raised seahorses are tank-raised seahorses are captive-raised seahorses or wild-caught seahorses or pet shop ponies are best quarantined for 30 days in order to be safe. For example, here is the quarantine protocol followed by the Shedd Aquarium:
Shedd Aquarium Seahorse Quarantine Protocol
The following schedule sets out the basic quarantine schedule for seahorses entering the John G. Shedd Aquarium. Application dates and specifics can be modified if it is deemed necessary.
Chloroquine used to be part of the quarantine process but has been discontinued as a result of sensitivity.
Seahorse quarantine = 30 days
(1) Panacur In Artemia adults or nauplii: soak at 250mg Panacur /kg food and feed out as per normal food over 3 days. Artemia can be used to gut-load other food types if necessary. Start treatment on day 10 through 13 and repeat on day 20 through 23.
(2) Praziquantel bath at 10ppm for 3 hours or 1ppm for 24 hours on Day 29.
(3) Vaccine (Alpha-Dip 2100): dip at 1 part vaccine to 9 parts water for 20 to 30 secs on Day 7 and repeat on day 14.
(4) Diagnostic dip — Osmotic (freshwater) dip on Day 30.
(5) DHADC Selco as an addition to normal food. Soak prior to feeding as per label instructions) on Days 1 through 7.
It’s very difficult to say what parasites may be involved in your case without knowing the symptoms exhibited by the seahorses that you lost, Cindy. I can tell you that Uronema is the most commonly seen protozoan parasite in syngnatids, but weak snick and related feeding disorders can be caused by a wide range of parasites that attack the gills and skin of their hosts. These include Cryptocaryon (uncommon), Amyloodinium (common), Brooklynella, Uronema (prevalent in store-bought fish), Costia, and Cryptobia parasites among the chief offenders (Wolf, 1998). In my experience, two protozoal ectoparasites, Amyloodinium ocellatum and Uronema marinum, seem to be responsible for the bulk of the problems in seahorses. All of the ectoparasites mentioned above commonly attack the gills and skin of their hosts. Respiratory distress, loss of appetite, erratic behavior, and "flashing" or scratching against objects are common symptoms for all of the above.
Formalin is effective against most of these parasites, including Uronema, but would wipe out your decorative invertebrates and cleanup crew and microfauna as well. The same thing would be true for most antiparasitic medications. You might consider treating the main tank with hyposalinity at a level that the invertebrates should tolerate, but hyposalinity does not eliminate Uronema, one of the most common parasites…
Here is an excerpt from my new book (Complete Guide to the Greater Seahorses in the Aquarium, unpublished) on Uronema, but bear in mind that an entirely different parasite may well be involved:
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 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.
These dreaded parasites also infect the gills, and as with Brooklynella, heavy gill infections may result in dead by suffocation before the characteristic skin lesions develop (Basleer, 2000). When skin lesion do appear, the open wounds invite secondary bacterial infections, which further complicate the clinical picture.
Microscopic examination of skin smears can confirm the diagnosis of Uronema. Under the microscope, Uronema marinum parasites appear as pear-shaped, single-celled ciliates with a single large macronucleus and long hairlike cilia at the rear end (Kollman, 2003). Numerous small (35-50 microns), fast-moving, oval or pear-shaped parasites will appear on skin and fin smears (Basleer, 2000).
Formalin, malachite green, or formaldehyde/malachite green combination drugs are effective treatments (Basleer, 2000). The treatment needs to be maintained for at least 21 days to cover the life cycle of the parasites. Chloroquine phosphate, quinine hydrochloride and quinacrine hydrochloride (antimalarial drugs) also work well but are difficult to obtain, difficult to use, and difficult to dispose of properly (Kollman, 2003).
Freshwater baths, concentrated baths in methylene blue, and hypersaline baths at 45-50 ppt are also very helpful. Even 10-second dips in a 3% hydrogen peroxide solution are known to be effective. The peroxide dipping solution is prepared by taking one gallon of dechlorinated freshwater and then removing 10-oz of the water and replacing it with 10-oz of 35% hydrogen peroxide instead. This formula will produce a 3% solution of hydrogen peroxide for the brief dip (Kollman, 2003).
There are mixed reports on the effectiveness of hyposalinity at eliminating Uronematids. Kollman highly recommends it, but the latest thinking on the subject indicates that hyposalinity is contradicted when treating Uronema (Kollman, 2003). For example, Thom Demas, the Senior Aquarist at the Tennessee Aquarium, finds that low salinity actually seems to encourage Uronema, whereas higher salinity thwarts it. He reports that raising the salinity of the system to 38-40 ppt while gradually lowering the temperature will greatly slow down the growth rate of Uronema and make it much easier to control (Demas, pers. com.). My latest experience treating Uronema with hyposalinity was decidedly negative and I also feel that hypersalinity produces better results for this parasite. It appears that Uronematids are unique among ectoparasites in their tolerance for hyposalinity, so treat accordingly. They cannot withstand freshwater, but hyposalinity seems to be quite another matter.
With all these different treatment options for Uronema, one would think that these parasites would be fairly easy to control. Nothing could be further from the truth! Uronema is a very stubborn pest and terribly difficult to eradicate from your system once and for all. The problem is that formalin, malachite green, and the various dips and baths all do a fine job of killing the Uronema ectoparasites that are on the skin and gills of the fish, but they cannot touch the parasites that have penetrated within the fish’s body. The parasites that are attacking the muscle tissue, internal organs, and red blood cells aren’t touched by such methods and they are the ones that do the irreparable damage. What is needed is therefore a way to get the antiparasitics inside the affected fish where they can kill the ciliates that have invaded the tissue.
Dr. Alistair Dove, the Aquatic Pathologist at the New York Aquarium, has found the solution. He reports that intramuscular injections of metronidazole at a dosage of 50mg/kg repeated every 72 hours for a total of 3 treatments work extremely well for eliminating Uronema in seahorses (Al Dove, pers. com.). The IM injections deliver the drug inside the seahorse’s body, precisely where it’s needed most. Of course, we humble hobbyists cannot manage such injections, but we sure can bioencapsulate metronidazole by gut-loading live shrimp with it and get the medication into our seahorses that way. That will allow us to attack the parasites from the inside and the outside at the same time.
Because Uronema is so difficult to control, Basleer recommends treating it with a combination of treatments. He suggests treating the main tank with formalin/malachite green and then adding daily baths in freshwater and concentrated methylene blue for best results (Basleer, 2000).
Lower the water temperature during the treatment period and stay on top of the water quality in your hospital tank. Make partial water changes as necessary to keep your aquarium parameters perfect. [End quote]
If you could confirm Uronema, injections of metronidazole would be the treatment of choice. If that’s not possible, I would treat the affected seahorse with formalin combined with malachite green in your hospital tank along with daily freshwater baths and/or dips in a concentrated solution of methylene blue or 3% hydrogen peroxide.
Let me know if you feel treating the main tank with hyposalinity might be worth a try, Cindy, and I will be happy to post the instructions for administering hyposalinity.
Best of luck resolving the situation, Cindy. Perhaps the fact that you haven’t had any losses for the last two weeks indicates that this outbreak of disease has almost run its course.
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