Fungus

[TomO]

About a month ago I had two Australian Rainbows succumb to fungus. So I treated my tank. Now one of my angels has fungus beginning on its head. Either I didn’t completely eradicate it or it’s come back around. 
What causes fungus? This is the only tank that ever gets diseases. 
I used API fungus cure. It turned my tank green.

 

if anyone knows of a better cure, please let me know.

[Fish Folk]

Are you positive the sickness is fungus? Could it be a bacterial infection, or a combination? Three things to consider doing: (1) do a large water change to improve water quality (2) Buy new food to ensure that your old food hasn't gone bad (3) Feed sparingly so as not to pollute water.

Now, if you're able, move the sick fish over to a separate quarantine tank to treat. As I understand it, fungus (as with bacteria)  is to be found in some amount in all aquatic ecosystems. Poor water quality and inadequate maintenance can contribute to build up (we've had it in some of our tanks). Feeding old food can be a cause. 

You can read about the API Fungus Cure here. The Instruction Manuals and FAQs may be insightful. I would use the product as described. Acriflavine and Malachite Green (i.e. Victoria Green) appear to be the main ingredients. Your water will turn greenish. If you have a HOB filter, putting the carbon back in should clear the water eventually of the meds _only after your whole round of treatment is complete_. 

Good luck. Sorry to hear about the fish sickness . . . it is a challenging part of the hobby. 

[TomO]

I just did a 30% water change. The food, I bought 2 weeks ago. None of my other tanks have problems with the same food container. But I just bought this food, maybe my old container was bad. 

[TomO]

My local pet store doesn’t carry enough fungus cure for my 75. I was able to dose half. My angel ended up dying. But I ordered enough from Amazon to dose the whole tank on Tuesday, just so the other fish won’t get sick.