Hemorrhagic septicemia?

Hello everyone. A friend told me about this forum when I explained a problem with my corys.

I have 4 peppered corys, with one being a female and she's the one showing these symptoms. She often has these red streaks along her side, as well as around the barbels and under the head. It looks like HS from what I've read. But the thing is this has been off and on for a few weeks and she never looks sick except for the redness. Also the redness heals in 24 hours or so then comes back in different spots. It's because of this I first thought she was injuring herself on a rock or substrate but I don't think so now.

The thing that confuses me is how it doesn't seem to be affecting her. She still digs through the sand substrate, eats fine and hangs out with the males. The other cory's seem fine.

The only meds I've tried is Melafix but it didn't seem to help. Water parameters are good, weekly water changes and there have been no ammonia/nitrite spikes or any other stresses I know of.

Do you think this is definately HS? Is it possible for the redness to disappear then come back days later with this disease? And sorry about the poor pic. She is very active. But you can just see the read under the mouth as well.

Ok. Should I try triple sulfa or what else would work? I think my tank maintenance schedule is fine.

Tank is 37 gal. Houses the cory's, couple of bristlenose, 2 dwarf gouramis and a few apple snails. Low-tech planted and plants growing great.

Just a question about the triple sulfa. I've been told it won't hurt plants and snails when used correctly, while others have said it's hit and miss. Should I be ok?

Thanks Lupin.

But can I ask if you know that from experience? I just checked over at applesnail.net, and some people have tested tetracycline and found it is safe with apple snails but not much else is (though they don't say what isn't). So which would be safer - tetracycline or the sulfa meds? For the plants and filter bacteria as well I mean.

Oh, and after chatting with my friend, he reminded me that when I got the cory's several months ago one had a small red streak on it's side. We thought it was an injury from being netted and it went away in a couple of days. I'm now sure that was the same markings as now. I think it came with the fish, not from my tank conditions. What if this is the viral form of HS? Should I be worried about the tank mates?

Ok thanks for your help mate. There is a lot about VHS on the net and I've seen it mentioned at other aquaria forums but I don't know if it actually occurs in tanks. Just thought I'd ask because I think this cory has brought HS to my tank. No other fish has these symptoms yet. And I don't see the use of treating in a QT since the bacteria can apparently effect the substrate. Or so I read.

Thanks again.