What's wrong with my fish?

[elizabethfclark]

Since May, I have had seven serpae tetras living happily in a heavily planted 10g tank with perfect water parameters and good filtration. Early on, they had a case of columnaris or something related (see earlier posts) that was eventually apparently cured by some combination of Kanaplex and medicated wonder shells (and lots of help from the people on this forum!). Whatever it was, I think it came from Petco and no longer seems to be an issue.

However, one of my fish is noticeably paler and skinnier than the other six. This particular fish also seems to experience more chasing and bullying than the other fish, but I don't know if that is a symptom or the cause. It usually finds somewhere out of the way fairly quickly. There is nothing else outwardly wrong with this fish. This was, however, the fish that was sickest during the earlier disease outbreak. Is it sick? Is it just stressed? Or is it fine and I'm just worrying too much? The other six are perfect specimens of health.

[Carl]

Elizabeth;
Since Columnaris is an opportunistic infection that can thrive even in otherwise well maintained aquariums, but is often brought on by stress and/or lack of healthy osmoregulation, this MAY be what is "going on"

This fish likely is a genetically weaker fish, or even if not, often being at the bottom of the "pecking order" can result in stress that can allow a foothold for this disease.

Isolating this fish from others in a way that reduces stress is definitely a "first step"

A medicated bath may be a next step, but even isolation might help if there no other symptoms other than what you are describing.
I would however increase sodium chloride (salt) to 1 teaspoon per gallon (not permanently), and add a Wonder Shell (maybe a Medicated version)

See:
www.americanaquariumproducts.com/MedicatedWonderShell.html

Reference:
www.americanaquariumproducts.com/Columnaris.html

Carl

[elizabethfclark]

Carl, thanks, as always, for your help! They already have a Wonder Shell but maybe I will give them another stint with a MWS.

What would be the best way to isolate this fish? To leave it in a breeder net in the same aquarium? Or to move it to a quarantine tank? Or simply to give it more places to hide?

[devonjohnsgard]

Elizabeth,
If you a extra hospital tank that would be best. Here some more information if need be.

www.americanaquariumproducts.com/Aquarium_Disease.html#quarantine

[babygeige]

A QT tank is a really great thing to have. It doesn't have to be fancy - I bought a basic 5 gallon tank, a small heater, and have a sponge filter in it. I don't even have a real light for it. I just use a desk lamp. Throw some basic decorations in there so the fish has somewhere to hide if it's nervous, and you're set. When the fish is recovered, you can put it back in the main tank, clean out the QT and put it away until the next emergency.
It's also very useful when you get new fish too!

[elizabethfclark]

I actually have a QT tank! The problem with using it is that I can't catch the fish in question...I've been trying, but he's not sick enough to be sluggish. Unfortunately, the little guys are really fast!

I did add salt, and they already had a Wonder Shell. I wish I felt like I could do something else though. He's not showing any symptoms other than being really skinny and pale, and the other six seem completely fine.