Yesterday I noticed one of my ember tetras looked odd. Where the rest of my embers are a sort of sleek, translucent orange, he's more peach-colored and looks a bit rough. I wouldn't say his scales are pineconed, but neither does he look as smooth as the others. Also, he looks a bit bloated. His eyes might be a tiny bit bulging too. He's also breathing more rapidly than the others.
It was water change day, so I did the change as scheduled but he spent the day hovering near the back and under the filter where it's darker. I expected him to be dead this morning, honestly. He wasn't. He ate with the same energy as the other fish, but after eating went back under the filter.
I turned the lights off again and he's no longer hovering there but swimming around the tank as normally as the others.
I know the tank has planaria so I wondered if he might not have some other parasite. I treated with fenbendazole yesterday and today.
No other fish are exhibiting any of these symptoms although a few of my other embers have been engaging in mating behaviors. Any idea what might be going on with this one guy?