# Weird disease? (Black patch)



## Fishyfishyfishy (Mar 3, 2008)

I recent saw some black patches (kind of like the black patches elderly people have on their skin) on my friend's red-tail columbian tetra. They are eating fine and been acting normal. The patches do not seem to move or have worms/parasite in them. I am very sure it is not scars from injuries. 

Only some of the columbian tetras has them. None of my other fish (clown loach, other kinds of tetras, etc.) has been "Infected". These balck pathes have been around for arond 9 months+.

Is aging the cuase of these black patches? I have never saw anything like this before. Any ideas or experience?


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## Katalyst (Jul 29, 2007)

Black patches are usually a sign of ammonia burn.


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## Fishyfishyfishy (Mar 3, 2008)

Wow ammonia burn. That is very serious. But how come other fish don't have them? And I THINK he does water change regularly.

Here is a picture: http://www.dkimages.com/discover/previews/862/15009982.JPG

In this picture, with your imagination, replace the red patch with a greyish path.

*His fish has multiple patches on both sides


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## proud2bcanadian (Nov 13, 2006)

If it's just on some of the one certain species of fish, it could just be them maturing. My best guess would be that the dominant males will have darker patches on them. I'm not too sure about Columbians as I've only had experience with young ones when they are shipped in.
I wouldn't think that ammonia burn would be around for 9+ months with the fish still living through it...


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## Katalyst (Jul 29, 2007)

Fishyfishyfishy said:


> Wow ammonia burn. That is very serious. But how come other fish don't have them? And I THINK he does water change regularly.
> 
> Here is a picture: http://www.dkimages.com/discover/previews/862/15009982.JPG
> 
> ...


That doesn't look like ammonia burn and I'd say its more grey then black. I missed the part about it being around for 9+ months. Sorry about that!


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## proud2bcanadian (Nov 13, 2006)

Hmm. I stand corrected. If it isn't maturing, then I guess they could just be scars from past ammonia spikes.
Were the columbians the first fish to be introduced into the tank in order to cycle it? Ammonia burns away at the slime coating on the fish, and the strength of that coating is determined by the fishes immune system which is unique to each species as well as each individual fish. That may be the reason that only some of the tetras have those black spots and some do not. Don't worry about it though because it just means that the fish has healed (if it was indeed ammonia burn).


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