Re:Stuck Trigger

#3700
Pete Giwojna
Guest

Dear Cindy:

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

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.

Respectfully,
Pete Giwojna


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