Corydoras sudden death

[Justbeginningfish]

I found The smallest peppered cory early this afternoon dead in a clump of hornwort, I assumed it was from stress after moving them to the big tank and sadly scooped him out.
I did a 15% water change just to be sure as i was worried about any pollution from his little body.
Checked the levels and everything is as it should be, no changes in temp, ph or nitrates.

Before moving them to the big tank we drained about 50% of their tank water and dripped in water from the big tank over the course of about 6 hours to get them acclimated, the water should have been fairly similar anyway since we do regular water changes and its coming from the same source.

All seemed fine tonight until about 1 am when I happened to notice a flurry of activity out of the corner of my eye and saw one of the cories swimming like mad and all spazzy trying to get to the surface.

I noticed blood on him so we quickly got out the gravel vac and clean bucket and siphoned out some water to be able to see what was going on. This took maybe a minute and half total and it was already too late, he was still alive but barely.

After he passed on we were able to get a good look and it looks like something was ruptured inside his little body, there was a pea sized area on his side between his gills and side-fin of bright red blood, but under the skin.
It has already faded a lot so im sure the same thing happened to the other guy but was already very faded by the time we found him

Everyone else seems healthy, the remaining three cories are fine, but so were these until whatever is happening happened.

Any ideas?

[Sponsors]

[Gar]

What sorts of decorations are in your tank, and what sort of tankmates?

From what you wrote it sounds like his body got torn on something - likely a decoration or piece of equipment..

[jaidexl]

I've seen this in the same area around the gill plate, some type of rupturing under the skin (albino cory, easy to see through). Could be septicemia but what it's brought on by, who knows. On mine, I noticed pale overall color and a cellular type structure in the area first, thought maybe eggs because it's a female, but that would be a weird spot for eggs. A week later the structure was replaced by blood streaks and the cory passed soon after. Chalked it up to old age.

[TLH]

Originally Posted by Justbeginningfish

Before moving them to the big tank we drained about 50% of their tank water and dripped in water from the big tank over the course of about 6 hours to get them acclimated, the water should have been fairly similar anyway since we do regular water changes and its coming from the same source.

All seemed fine tonight until about 1 am when I happened to notice a flurry of activity out of the corner of my eye and saw one of the cories swimming like mad and all spazzy trying to get to the surface.

Any ideas?

You say they should have but have both tanks got the same parameters?

Fish rushing about and "spazzy", possibly trying to jump out of the tank, suggests acidosis or alkalosis because you changed the PH too fast. Was this the only fish showing signs and what other stock have you got in the tank?

[Justbeginningfish]

The water tested the same in both tanks, same temp same ph same everything.

They are with a common pleco..the guy was wrong about species, he is around 5 inches right now, he can be a bit boiserous when he comes out to eat but its not aggressive that I can tell
two flame dwarf qouramis that ignore them totally and often eat from the same food tablet as the cories with no squabbles
one quarter sized gold ram
two tiny shistura loaches that we never really see

[aquanut415]

i just lost 5-6 sterbai's to the same type of thing i think. no idea what caused the deaths, but all the fish looked like they died of internal bleeding. since then, i haven't lost anymore, and also haven't changed anything in my setup. wierd.

[Justbeginningfish]

well the third and last peppered cory is totally missing, i have looked through the whole tank, moved all the driftwood and sifted through all the plants and couldnt find him.
The two scwartzis seem fine as does everyone else, I would think if it was a quality problem the Ram would be suffering as well.

The two tiny loaches arent actually so tiny anymore, they are still small but I am wondering if they didnt chase them into something. Do Shistura type loaches have those spikes as well? they can be a little bit snarky at times so I am wondering if they maybe are the culprit.

[matt s]

Now you have me scared ={ i just bought 4 cories to add to my current tank and one of them has red in the gill area, he had it when i bought him. Could this just be the color of his gill too? or is it most likely this sickness?

[Justbeginningfish]

This is below/behind(towards the tail on the side) the gill and an area of obvious bleeding under the skin
keep an eye on the one with the red gill though, flukes might be a reason?

[mistergreen]

could be a viral/bacterial infection.. I've been hearing of mysterious deaths lately. I wonder if something is floating around....

There was talk of a hemorrhagic disease in the N. America wild population earlier this year.

But it could be parasites too...
I'd treat your whole tank for a general parasite treatment.... At least that's curable.

[Birdy]

I woke up this morning to a dying cory cat! I only had him 2 weeks. Yesterday he seemed more peaceful than usual. This morning he was breathing heavy and just sitting the bottom of the tank. Needless to say I scooped him out. He also had some red around his gills and under his mouth. His face looked like his tankmates might have started picking on him.

He lived with a couple of Dwarf Gouramis, GBRs, and a handful of Tetras. Nobody really bothered him on a regular basis...usually just in passing.

Now I don't know if I want to run out and get another one

[lauraleellbp]

Yes all loaches have those spikes under their eyes, and IME loaches can get pretty aggressive at feeding time, this might bring them in contact with the cories; just one more thing to keep an eye on?