Gram-negative or Gram-positive?

noctcrawler

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Nov 17, 2008
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How can you tell if your fish are infected with a Gram-negative or Gram-positive bacteria? Are there any commercially available test kits for this?
 
I'm sorry I just noticed that no one replied to your question. I'm not an expert, but I have been working on gaining knowledge and experience in fish and fishkeeping.

Technically there's not really a way to do that unless you have a microscope.

However, most of the infections and illnesses you see in the aquarium are caused by gram negative bacteria. These include Aeromonas, Flavobacterium columnare (Columnaris) Vibrio, and Pseudomonas species.

The gram positive bacteria that you see most often causing disease in the aquarium would be Streptococcus, Mycobaterium which causes tuberculosis in fish, and Staph. Some others, too, I think, but gram negative are most common.

Since most fish keepers don't have a microscope nor do we (I'm sure many do) know how to do a culture, then stain and view under a microscope and then know what we were looking at, we have to go on signs and symptoms to make a diagnosis.

I think most would agree that you should treat bacterial infections with a broad spectrum antibiotic or a combination that would give coverage.

Kanamycin is a good antibiotic that treats gram negative with effectiveness on sensitive gram positive bacteria, but the combination of Maracyn and Maracyn II gives good broad spectrum coverage, and I've had success with that combination. There are many others out there that are very effective.

I think if you have been treating for three days and see no improvement then another antibiotic should be tried.

I guess I've rambled on beyond the answer to your question. The answer is that you base your judgement of whether it's gram negative or gram positive based on the physical signs and symptoms, contributing factors, the course of the illness and response to the antibiotic chosen.




 
When I am unsure of the cause and type of infection I use Maracyn and Maracyn-II like Melody suggested. They are made to work together unlike other meds.

I have no faith in Pima-fix or Mela-fix to handle problems as they are homeopathic.
 
Jeff, you are correct. Melafix and Pimafix are not corrective treatments. They work better as preventive treatments however I am not a fan of these treatments and prefer to maintain clean water quality than do the corrective treatments with the exception of praziquantel which is a mild treatment for flukes and internal parasites but that's another story. Just thought I'd throw a good example and exception of which treatments can be used without actually wasting your time and money for nothing.
 
I have no faith in Pima-fix or Mela-fix to handle problems as they are homeopathic.

They are not homeopathic, they work by killing/inhibiting disease organisms, just like all other medications. You are possibly confusing homeopathic with herbal? If so, they are quite different.
 
Can you tell us a little about the symptoms of the fish? Maybe we can help you decide which to use.

Remember your biofilter is bacteria, so use caution- and preferably a hospital tank - when using antibiotics so you don't UN cycle your tank.

I will say that I do not ever use antibiotics in the aquarium. I do use melafix - which is herbal/homeopathic and IME works great and is very mild. The most important thing you can do is keep the water really clean- 0 ammonia and nitrite and very low nitrate.
 
Let us know if we can help.

Clean water is your best defense against disease and illness, and can work wonders even when there is something going on with their health.

Fish have amazing immune systems if their water is kept pristine, so whatever is going on the first thing I'd do is make sure there's no ammonia and/or nitrites in the tank... zilch... nada. Big, frequent water changes if necessary to remove those toxic byproducts. Keep nitrates 20 or lower.

Prime conditioner is a life saver. It removes chlorine and chloramines, and detoxifies ammonia and nitrites for about 24 hours, giving you breathing room to do the water changes you must do to keep their water pristine.

Avoid using chemical adjusters for ph, or to clear algae.

I hope everything's alright with your fishy friends.:)
 
Homeopathic refers to herbal or natural treatments i.e. non-medicinal based treatment by which the herb is diluted through succession.
 
Unless you have a microscope and Gentian violet (aka Methyl Violet 10BNS) laying around the house, there isn't a practical way to tell the difference between a gram-negative or gram-positive bacterial infection. If you suspect an active bacterial infection, the safest bet is to treat for both. I recommend Maracyn and Maracyn 2 -- both are safe for BFB (biofilter bacteria), although they will decrease BFB activity. (And remember to remove activated carbon before beginning treatment with either.)

I have no faith in Pima-fix or Mela-fix to handle problems as they are homeopathic.
I have no faith in either Pima-fix or Mela-fix because in my experience neither actually works. And the label on both bottles uses language suggesting that both can be used to treat active disease. Yeah, and you can use snake oil too, to the same effect.
 
Can you tell us a little about the symptoms of the fish? Maybe we can help you decide which to use.

Remember your biofilter is bacteria, so use caution- and preferably a hospital tank - when using antibiotics so you don't UN cycle your tank.

I will say that I do not ever use antibiotics in the aquarium. I do use melafix - which is herbal/homeopathic and IME works great and is very mild. The most important thing you can do is keep the water really clean- 0 ammonia and nitrite and very low nitrate.

I agree. Have not had much success in the past using meds. Water changes, quarintine thanks and sometimes melafix/pimafix is what I do now if something is amiss with a fish.
 
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