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Ask the Expert

Ask the Expert

Dr. Greg Lewbart

Greg Lewbart is a veterinarian and a professor of aquatic, wildlife, and zoologic medicine at North Carolina State University. Dr. Lewbart's specialty is the care and treatment of ornamental fish such as goldfish, Koi, and other aquarium fish. He directs NC State's aquatic medicine residency program, which was the first of its kind in the world. Dr. Lewbart is also the faculty advisor for the NC State Turtle Rescue Team, which provides husbandry and medical care to turtles.

Greg Lewbart answered selected viewer questions about fish medicine, being a vet, and other topics on October 21, 2005. Please note we are no longer accepting questions, but please see our links and books section for additional related information.

Q: How different is it to do surgical procedures on saltwater fish compared to freshwater fish?

A: Dear Kenny,

That's an interesting question. The short answer is that it's not that different. There are some species-specific issues regarding anesthesia concentrations (some species like eels may require more and other species less) but in general it's very similar to freshwater fish surgery. Of course, you need to make sure you have plenty of clean seawater available for the procedure and to recover the fish after the surgery.

Q: Dear Dr. Lewbart,

I am 11 and I love animals, especially fish. I want to be a veterinarian. When did you decide you wanted to be a vet, and do you have any advice for me about how to study the right things to become a good vet?
James, Wichita, Kansas

A: Dear James,

I'm very glad to hear that you want to be a veterinarian! And it sounds like you're a bit ahead of me when I was younger! I decided I wanted to be a vet when I was about 14. Our cat Patches was hit by a car, and I was very impressed by the care she received by our veterinarian, Dr. Bookman, and how well she recovered. I ended up volunteering and later working for Dr. Bookman before I went to college.

As or studying advice, I would say study hard and get good grades, especially when you get to college. At the same time, it's important to be well rounded, so playing sports and being active in extracurricular activities like clubs and service organizations is important. Finally, it's important to be persistent! It took me three times to get into veterinary school (I was rejected twice), but I kept at it. Once you have a goal, and a dream, you can achieve it if you work hard! By the way, you have an excellent school of veterinary medicine (KSU) in your state.

Q: Hi Doc,

I really enjoyed the segment about your practice. You mentioned a book that instructs fish owners how to train their pets. What is the name of it or any other related resources for fish-human bonding?
James, Miami, Florida

A: Dear James,

Yes, I'm glad you asked about the book. It's called How to Train Goldfish Using Marine Mammal Training Techniques. It's written by a man named C. Scott Johnson but is now out of print. The ISBN# is: 0533112923. You may be able to find it on the Internet or though a used book store. Good luck!

Q: I heard that you could give a sweet pea to a fish that has swim bladder problems. The pea is supposed to counteract buoyancy disorder. Is this true? Is this something fish owners can try at home without harming the fish?
Lea Griffis, Conyers, Georgia

A: Dear Lea,

Ah yes, the green pea treatment. I recommend it frequently (it's inexpensive and is unlikely to harm the fish). I first learned of this many years ago from someone in a pet store. Fancy goldfish in particular are frequently afflicted with buoyancy disorders (usually they are positively buoyant and float either on their back or their side). Sometimes this condition improves or worsens shortly after eating. There are many theories as to why this occurs, and it's possible that a number of causes are to blame. Certainly in some cases the swimbladder is abnormally shaped or diseased. Excess gas in the gastrointestinal tract could also cause the problem.

We think green peas might help because they are high in fiber and are probably denser than floating flake or pelleted foods. Also, since they tend to sink, it's less likely that a fish eating peas will ingest air from the surface at the same time.

Just this past week I read an e-mail from a veterinarian whose client was feeding a lot of green peas and the goldfish actually started to turn green! Now, this is an anecdotal report, but I guess it's possible. We normally recommend one green pea per fish per day. Frozen and thawed or canned peas seem to work well and it helps to lightly squash them so the fish can get to the inside of the pea.

Q: Are there any diseases that humans can catch from their pet fish or fish can catch from humans? If so, how common are they?
Mary Barron, Albuquerque, New Mexico

A: Dear Mary,

I don't know of any diseases that pet fish can catch from their owners but there are some diseases that people can catch from pet fish. We call these diseases, those that can go from animals to humans, zoonotic diseases or zoonoses.

The first and probably most common is mycobacteriosis. This condition is sometimes called "aquarium finger." Although related to the organism that causes tuberculosis in humans, the species of Mycobacterium that fish can carry does not cause tuberculosis in humans. Sometimes fish mycobacteriosis is incorrectly referred to as "fish TB." Humans are most susceptible to this disease when they have open cuts or sores on their hands when they handle or touch fish. It's also possible to contract this disease by coming in contact with contaminated water. Finally, people who are immuno-compromised (have weak immune systems) are more likely to contract "aquarium finger" than young, healthy people.

The disease can be treated but it can take several months to cure. Generally, the lesions are restricted to the hands and extremities. This is because the fish bacteria grows best at fish temperatures (temperature of the aquarium or pond) and not human body temperature (98.6 F). Since our hands and fingers are cooler than our core body temperature, the bacteria can survive and multiply in the extremities. Here are some tips to prevent this problem (which I have never observed by the way):

  1. Always wash your hands well after touching fish or aquarium water.

  2. Wear latex gloves when handling fish (you may have noticed we were always wearing gloves when working with the fish in the NOVA segment).

  3. Don't handle fish or aquarium water if you have an open cut or sore.

Aquarium water has been linked to other bacterial disease (e.g., shigellosis) of humans but this is pretty rare. Overall, fish are very safe pets for people and the incidence of zoonotic disease is low.

Q: I have a pair of goldfish. They are six years old and have a baby that is one. The adults are extremely big—Koi-sized—and have had no health problems so far. Should I take the young fish out of the tank before the adults mate again? My tank is about 75 gallons, and they are the only fish in the tank. Thank you for your time.
Stephanie Selznick, Quincy, Massachusetts

A: Dear Stephanie,

Are you trying to raise more goldfish? I can't think of a good reason to remove the juvenile, unless you think the adults might injure/consume it or that having more fish (the adults plus the juvenile) in the tank might reduce the number of eggs once the adults spawn. I don't think having the one-year-old fish present would present any problems, but with the size of the adults, you'll probably want to minimize the bioload on this aquarium at some point.

I hope this is helpful.

Q: Do fish feel pain? I noted in the broadcast segment that they were being treated with anesthesia during surgery, but is this merely to keep them calm or can they actually feel pain?

A: Dear Anonymous,

I think fish feel pain. At least I'm convinced they can perceive noxious stimuli and react accordingly (e.g., flipping or flopping when injected with an antibiotic or other drug). A lot of research is ongoing in this area and sometimes the results aren't conclusive. Nevertheless, we were giving an analgesic (pain medication) for pain management and not to calm the fish.

Q: Dr. Lewbart,

How common is it now for vets to have expertise with fish? Is it likely that in any major city you could find a vet who treats fish?

A: Dear Anonymous,

I would estimate there are between 50 and 100 veterinarians in the United States that regularly (at least once a month) treat or consult on pet fish clinical cases. I would say that there should be at least one of these veterinarians in or within close proximity to most major metropolitan areas. I know in North Carolina both Raleigh and Charlotte (the largest cities in the state) have private practitioners that treat pet fish on a regular basis.

Q: What is the cause of high mortality in recently imported Hatchetfish characins (Carnegiella strigata) and pygmy Corydoras pygmaeus at the wholesale level? Do you have any information on this?
Bill Thomas, Olympia, Washington

A: Dear Bill,

Good but tough question. I worked in the wholesale pet fish industry for almost five years so I saw a lot of recently imported wild South American fishes. However, without performing a thorough physical examination or necropsy, I can't comment on any specific causes of mortality in these species. I can tell you that these wild-caught fishes, during the sometimes lengthy time interval from capture to a holding aquarium in the United States, are subjected to a variety of stressors that may include crowding, poor water quality, temperature extremes/fluctuations, net trauma, malnutrition, and contact with other fishes that may be infected with a contagious disease.

For specific answers, your best bet would be to submit fresh samples to a local diagnostic laboratory. I would be happy to help locate one for you in your area.

Q: Dr. Lewbart,

How do you think Hurricane Katrina affected nondomestic animals in the Gulf region? Are animals able to naturally protect themselves in weather situations like this, or do they suffer as much physically as humans do during and in the aftermath of a major storm?
Carrie Oaks, Shreveport, Louisiana

A: Dear Carrie,

I'm certainly no expert, but my general impression (having been through a couple of Category 1 storms), is that wild animals fare remarkably well during hurricanes. Think about this: they don't rely on electricity, grocery stores, plumbing, motor vehicles, mail delivery, etc. And they don't have houses and apartments that can be flooded or washed away. Of course, some tree-dwelling species certainly suffer, but I think that overall wild species are adapted quite well to hurricanes and other natural disasters.

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