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Re: HELP a disease question!
At 10:47 AM 12/4/2001 -0800, you wrote:
>Robert E.
>
>"by way of Barry Cooper " wrote:
>>
>> Hi all,
>>
>> I have a disease problem breaking out in one tank and I need help. The
>> fish in question are breeder hi fin swords -- third generation aquarium line
>> bred and big and nice. This is the parent tank and my entire stock right now.
>> The disease looks like one of the protozoa/parasites one sees on pond raised
>> livebearers. It started about 2 weeks ago. An old female showed it. It looks
>> like very big, clumpy ich on the body and fins. The fin form looks like a
>> soft cyst and the body form looks like it breaks out from under the skin. I
>> would say they are about 2 - 4 times the size of ich. It progresses slowly
>> and never totally covers the fish like ich. It is on one of my younger red
>> velvet females -- one I had real hopes for too! I have tried Neosulfex
>> (neomyacin and 5 sulfur drugs mix), Livebearer, a formaldyhide, copper
>> sulfate and malachite green mix by Aquatronics and flubendazole. Nothing
>> seems to stop it. Does anyone have any idea what this is or how to stop it?
>
>Using antibiotics without knowing the pathogen, and without knowing exactly
>how much and how long the treatment needs to be, deserves a far stronger
>statement than I'm willing to make here.
>
>> The water is moderately hard and alkaline. There are a dozen 5 inch fish
>> in a bare 55 with two large potted swordplants, najas, a big box filter, an
>> airstone and an Eheim 2226 professional. 75% water changes every week or two
>> at the most. Food is live daphnia, frozen bloodworms, frozen brine shrimp,
>> live baby brine, Hikari micropellets, freeze dried bloodworms, live
>> blackworms a few times, live adult brine shrimp, Ocean Nutritition flakes,
>> microworms and other flakes. Mostly the meaty foods though. The only fish
>> introduced were some fowleri and erhardti corys about 3 or 4 months ago. They
>> had been in my tanks for 9 months with other fish and no problem. There are
>> some sterbai in there too and have been there for over a year and a half.
>> There are snails in the tank. No salt in the water. Temperature is 75F.
>> Raising it now to 80F. all other tanks of fish with the same diet are fine --
>> killies and swords.
>> Let me know what you think as soon as you can.
>
>Remote diagnosis is nearly impossible, but your descriptions strongly indicate
>a bacterial infection, and not an external parasite.
I agree that remote diagnosis is nearly impossible. However, I would not agree that this is necessarily bacterial in origin. It could be lymphocystis (a viral disease), protozoal, or bacterial, or even parasitic. The best approach would be to fix one or a few fish and send them to a competent fish pathologist. Dr. Ed Noga at NC State would be a good choice. You'd have to contact him to establish fees, etc.
>Raising the temperature
>under such circumstances is exactly the wrong thing to do. Keep the fish near
>the lower end of their optimum range, to keep oxygen levels up and help their
>immune system fight a slower-growing bacterial attack. Heat helps the bacteria
>more than the fish, sometimes.
I disagree with this. Host responses to bacterial pathogens are usually enhanced by increased temperature, within physiological reason. In mammals that is why we get fevers. Moderate fevers benefit the host, not the bacteria. The reasons include enhancement of phagocytic function, amongst others. There may be studies on fish specifically, but in poikilotherms like lizards, animals with bacterial infection will move, if given the opportunity, to a warmer environment. Studies were done years ago showing that if that adaptive response (their answer to fever) was prevented the survival rate of the animals was reduced (more died).
>One of the likliest (often somewhat species-specific) bacterium to exhibit
>similar symptoms is *Mycobacterium marinum*. If that is what it is, you should
>probably sacrifice any fish with obvious lesions, and isolate the tank and
>inhabitants from any others you may have. Keep hands out of the water, too. [I
>can speak from experience that it is something you don't want to get in a
>slight cut or hangnail. The cure is very long, very expensive, and the
>discomfort is serious.]
My own experience is that Mycobacterial infections in fish usually (stress usually) produce diffuse lesions, often showing up as "dropsy", not discrete granulomas, which would appear as lumps. I would bet against Mycobacterial infection in this case. The key to knowing what to do is proper diagnosis and I encourage you to sacrifice some fish, if you can, to get it.
Barry
___________________________________________________
Barry J. Cooper, Prof., Dept. Biomedical Sciences, Cornell University
Current address: 27505 Riggs Hill Rd.
Sweet Home, OR 97386 (bjc3 at cornell_edu)
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