Cory ich: best treatment?

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I live in upstate NY; out GH is 180. We live on limestone, and have quite hard water.

Here’s a clear picture; any guesses on what’s going on? Large grey hole in side.


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I did a big water change and gravel vacuum, the third in five days. He’s listing on the bottom of the tank today; I’m not optimistic. My money is on hexamitiasis/‘hole in head’ disease. I had a fish in the same tank with it a few months ago. General cure worked well on her, but I am guessing it may have lingered in the tank at low levels, and the stress of the high temps weakened his immune system enough that he got sick.
This guppy is the last of our store bought ones; the rest are all second generation. Hopefully they will be more resilient to our rookie fish owner errors.
On what signs is your bet based?
To me there isn't any symptom of Hexamita visible. Hexamita doesn't linger at low levels and doesn't infect due to a weakened immune system.
Don't treat based on assumptions.
Mainly based on the big hole in his side. I would very much like to learn what other issues could cause this, so I can either try to correct it or know what action to take if this happens with any of the other fish in the tank. Do you have any suggestions what it might be?

Poor Cobra. Other guppies have had fish who stayed by them when they were sick; all the other fish are ignoring him. He hounded the females pretty relentlessly.

Hexamitiasis – Hole in the Head or Body​



From common guppy diseases on
“The first sign of Hexamitiasis is fish waste that appears white and stringy. Then their colors began to pale. They will refuse to eat. Lesions will eventually appear. Most often, they are on the body of the Guppy.” common guppy diseases: “Unless your fish has a literal hole in the head caused by an aggressive fish, the protozoan parasite Hexamita is the most common cause of hole in the head or body.”
Final post:

The Ick treatment (heat, no salt, frequent water changes) worked very well to clear up ick symptoms in the bronze cories. I didn’t change the water as much in the second week of treatment, and the oldest guppy picked up an unknown disease and died within a week of returning to normal temps. The remaining 10 fish seem healthy at this time. Thanks, everyone, for your assist with our fish emergency; I am so grateful that you-all are here to field questions and share knowledge.
Thanks, Double Dutch! I hadn’t heard of this one. It certainly matches the strong ones and some of the color change, but I don’t see anything in it about creating holes in the fish. I will add this to my list of potentials for the next sick fish; thank you!

Do you have any recommendations for a book on tropical fish care that is science based? I would really like to move beyond website-surfing for diagnosis, as it seems like a losing game from my fishs’ perspective. I just don’t know enough about the sources to judge their information well.

I’m really grateful for this forum, which has provided so much timely advice and saved four fish so far in under a year.
Diagnosing fish health issues is very difficult for most of us, but a good book is The Manual of Fish Health written by biologists (Dr. Chris Andrews, Adrian Excell, Dr. Neville Carrington with Dr. Peter Burgess and Peter Scott). The first half covering fish requirements and how to prevent health issues is incredibly factual and beneficial. Published by Firefly Books in 2010.

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