FusedJaw: Seahorses, Pipefish & Seadragons

Disease Prevention, Diagnosis and Treatment

During the past decade prevention, diagnosis and treatment of disease in Leafy seadragons have been some of the greatest challenges in maintaining a successful collection of these animals.

Syngnathids are often sensitive to medications or dosages used to treat other marine teleosts, and often are not subject to the same type of parasitic infestations that commonly plague other marine fish. Prevention of a disease outbreak is the key, and holding the animals off exhibit for observation and quarantine is often the answer.

The Syngnathid Health Management Chapter of the Seahorse Husbandry Manual contains information that has been used by the Shedd Aquarium to quarantine and treat their syngnathid collection (Greenwell 2005). This chapter contains valuable information in terms of disease diagnosis and treatments.

The most common problems reported by institutions displaying Leafy seadragons are ciliated protozoan infestations such as Uronema spp., Mycobacterium spp. infections, and buoyancy problems related to stress, injury or disease. Infestations of internal parasites such as nematodes and trematodes have been less commonly reported, but do occur.

Good husbandry practices, adequate diet and minimal environmental stress such as temperature or lighting changes can help to prevent the problems described above.

In the event that a disease or parasitic outbreak is suspected, always consult with a veterinarian prior to administering any treatment.

Several institutions have reported success in treating ciliated protozoan infestations with formalin either in a long term bath or as a short dip. Generally the formalin is used in a lower dose than with most teleosts, and for a shorter duration. The Tennessee Aquarium uses formalin in a long term bath at 25 ppm. This is a 24 hour bath for 4-7 days with water changes between doses (Alford 2005). The Shedd Aquarium reports using formalin in a 10 minute dip at 200 ppm (Greenwell 2005).

In addition, hyper-salinity has been used to reduce problems with ciliates. The Tennessee Aquarium keeps the salinity in their seadragon systems at 36-39 ppt (Alford 2005).

Adequate UV sterilization and preventative antibiotic treatment may help in the prevention of Mycobacteria infections. The Dallas World Aquarium uses a mixture of rifampin and minocycline antibiotics on a quarterly basis as a food additive to help in the prevention of this disease. The antibiotic is added to a mixture of RO water and live Artemia nauplii. The nauplii are allowed to soak in the antibiotics for up to 20 minutes, the entire mixture is then poured into the container with live Mysidopsis bahia that are being acclimated to the colder system water. After approximately 30 minutes the mysid shrimp have become “gut loaded” with the medicated nauplii and are fed to the seadragons. The sudden onset of buoyancy related problems in Leafy seadragons can be caused by environmental stress such as aggression, lighting or temperature changes, or extensive breeding behavior. Additionally, intestinal blockages or disease can cause a seadragon to float abnormally at the surface, or sink to the bottom of the aquarium. Generally the problem occurs when the airbladder becomes over or under inflated.

Aquarium veterinarians and biologists have tried a number of different methods to treat these problems. Placing the dragon into a container and sinking it to the deepest part of the exhibit has been successful, on occasion, especially when the problem is due to a sudden stress such as lighting changes or stress during exhibit cleaning.

For suspected intestinal blockages, a low salinity bath (roughly 16 ppt for 10 min – 1 hr) can be used to help the seadragon pass a foreign object such as a rock, or a particularly large fecal mass.

If antibiotics or other medications are chosen to treat a buoyancy problem, the dragon can be weighed by removing it from the water and placing it on a scale directly, or by weighing the dragon in a container with water. (The dry method may be more accurate) (Gomezjurado 2005; Verdugo 2005).

If the buoyancy issue cannot be immediately resolved, a number of institutions report that they have been able to reverse the condition with the use of acetazolamide or ceftazidime via injection. Also, tapping the airbladder and removing the excess air, followed by treatment with an antibiotic such as ceftazidime is also recommended (Greenwell 2002; Verdugo 2005).

If a seadragon is not eating (which is often the case with the conditions mentioned above) tube feeding can be an effective way to keep it from becoming anorexic. A variety of tubing methods and formulas are used. Most institutions report using a mixture of frozen or live mysid shrimp, (or other fish meals) blended with a 2.5% dextrose solution and fed through the snout via a tube into the stomach. A small diameter catheter such as a cat catheter, or butterfly catheter works well. This method is best performed while gently holding the dragon’s snout underwater to reduce air intake into the gut. The length of the catheter should be measured prior to the feeding to ensure proper placement into the stomach, which is just past the bend of the neck. Depending on the size of the seadragon, small amounts of the gruel should be given (.02-.25 cc). This procedure can be used daily and can also be an effective way of introducing antibiotics or anti-parasitic medications (Robertson 2005).

The treatment of disease in Leafy seadragons is still very much a process of trial and error. With continued collaboration and communication between institutions displaying Leafy seadragons, the future looks promising.

Collection Management

Leafy Seadragons on display. Photo courtesy of OctopusHat.

Following, is a quote from Dr. Rod Connolly, Senior Lecturer in Marine Ecology, School of Environmental and Applied Sciences, Griffith University, Queensland Australia. Rod has been researching the behavior of Leafy seadragons in their natural environment for many years.

“Leafy seadragons are iconic in southern Australian waters, and are a flagship species of conservation programs and the creation of marine protected areas. Their conservation status is unknown because population trends have not been measured. Threats from human activities include incidental catch during commercial trawl fishing and the loss and degradation of habitat from pollution” (Connolly 2005).

Should public aquariums become successful in breeding Leafy seadragons, a collection management plan will become an important tool in future cooperative breeding efforts. It is important at this point that accurate, detailed records of acquisition be maintained. It is unknown if there is a large degree of genetic variation in wild Leafy seadragons due to their limited geographical range and mating habits. Since many institutions begin their collections with young of the year siblings, and collection of specimens from the wild is either entirely prohibited or extremely limited, exchange of adults from different year classes may be necessary in order to maintain genetic strength of captive species.

As aquarium scientists, we have an incredible opportunity to gather information and collaborate with other scientists working with Leafy seadragons around the world. This sharing of information will prove to be invaluable as we endeavor to ensure the survival of seadragon species both in their natural environment and in our aquarium collections.

Share This

Pages: 1 2 3 4 5 6

This entry was posted on Friday, May 29th, 2009 at 7:00 am and is filed under Advanced Care. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.