Goldfish gone black in 12 hours

Question
Hi
We talked before and I told you that I rescued a small goldfish from my dermatologists office. He has swim bladder disease for days as far as they knew and wasn't getting better. Well, he is better in my tank. However, when I got him, he had two small black specks on his body. I never thought much about it.
A week after introducing him to my tank, his caudal fins went black and so did his dorsal fin. He also has black specks on his body and gills. I brought him to my local aquarium specialists here. They confirmed that it was a fungal disease. As with treating my other fish, I continue to do a 10% water change on a daily basis to regulate the water.
My fish are all active swimmers.
I am not sure what to do about this little black fish. There is Melafix in the tank right now. And I do the water changes. I use a Natural Regulator in the water. Aside from using an airstone and providing plenty of daylight and not overfeeding, I am doing nothing else. I've tried antibiotic foods with no success.
Do you have any suggestions?

Answer
Hi Bernadette, sorry to hear about your troubles.

This fish sounded like it wasn't being kept in proper conditions before you took it into your care. Swim bladder disease is an environmental condition caused by poor nutrition and/or poor water quality.

So, chances are that the spots you see are due to environmental issues that it had before you adopted it. I found a couple of articles that you will want to read:

http://www.kokosgoldfish.com/Melanophore%20Migration.html
http://www.koivet.com/html/articles/articles_details.php?article_id=106&category...

This is the closest I could find to what you are describing.  It doesn't suggest that what your fish is experiencing is a fungal infection. It makes more sense to me that your new goldfish underwent a previous trauma and is healing now. Especially if appetite and activity levels are normal.

Ammonia burn (due to high nitrites such as those found in an uncycled tank) can cause necroses that would appear as black patches, but if this were the case, there would be other symptoms such as gasping for air at the surface. Besides, your tanks are established and you are using your test kits! So, you would know if you had detectable nitrite or ammonia.

Just keep providing your goldfish with good care, very clean water and nutritious foods, and I believe it will see a recovery. Don't overdo the Melafix, it can start to build-up in the water, especially if you follow the package's directions which tell you to keep adding more every day without doing a water change! I honestly don't think this tea tree oil derivative does much good, myself. I have used it on occasion during times of stress, but only at half doses and never for the entire week the way it prescribes.

Again, if your goldfish is eating, bright-eyed and bushy-tailed with normal movements, I would not be overly concerned. I would not advise treating with a fungal remedy, since I don't believe that's the case here...not with the description you have provided, anyhow. Of course, your vet has the benefit of seeing the patient in question.

Good luck, Bernadette. I applaud your act of mercy, and I think this goldfish will pull through with continued care and vigilance, without meds or extraordinary measures.

Nicole