What was wrong with my fish?

[raymond82]

Today I had to euthanize a male A. eremnopyge that was really sick. It started around two weeks ago, when I noticed he couldn't close his mouth properly. Below his chin (not sure if that's the correct word for it) I could see two small pieces of skin sticking out. He seemed to be doing ok otherwise until he spawned with the female and she chased him into a corner. I took him out and his chin now looked pinkish and therefore I separated him. After that it only got worse, I treated him with a broad medicine since I didn't know what exactly caused his illness and today I found that the spot in his chin had become and open wound, there was fungus growing on the other side of his head, his scales were standing out and he had stringy white mucous-like poo. I therefore immediately euthanized him.

At first I thought that it was just a damage to the skin but do the symptoms match any parasitic or bacterial infection?

 

[gerald]

Sounds like Mycobacterium - very common in cichlids, gouramis, and rainbowfish especially.
See Diana Walstad's article on Myco: www.atlasbooks.com/marktplc/00388mycoarticle.pdf
also Univ. Florida On-Line Aquaculture Library.

 

[raymond82]

Sounds like a serious problem, the Mycobacterium. I read the article and not all symptoms match but a lot of them do, I think I should start doing autopsies to get to know fish diseases a bit better. Is there a guideline for doing autopsies on fish?

I have a UV filter so maybe I'll have to start using it to fight of the infection. Thanks also for the Univ. Florida On-Line Aquaculture Library, that's a very interesting website. I found quite some interesting articles on a range of things!

 

[gerald]

Myco is "usually" pretty easy to diagnose in an autopsy (necropsy?) of a freshly-dead fish. Look at the kidney, spleen and liver, which are often the organs most visibly infected. Normally they are smooth red-brown color. (Cut open some non-infected fish so you'll know what "normal" organs look like). If these organs have pale or dark spots that look like sand grains (can be pale gray, yellow, pink, brown), that's most likely Mycobacterium granulomas. You may be able to see the granulomas with your eyes alone, but a low-power magnifying lens (5 to 10 x) helps, especially for tiny fish. It's Best to kill the fish before it dies naturally, so you're not confused by organ color changes that occur after death. Then wash and disinfect your hands REALLY well. If fish Myco gets into scratches or cracks in your skin it can infect you too.

Here's a particularly severe case in a goldfish. Most fish would be long dead before it got this extreme.
http://www.koi-pond-guide.com/images/mycobacteria.jpg

 

[raymond82]

Thanks for the advice, I think I'll try to get a scalpel and some tweezers to be able to do this in the future. I've thought about it before whenever a fish would die because of unknown reasons.