3 Cory deaths - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 9 Old 03-17-2008, 03:08 PM Thread Starter
3 Cory deaths

I have a 29-gallon established tank.

2 juvenile angels
4 black skirt tetras
1 female betta
1 male swordtail
4 zebra danios
2 baby cory cats (used to be 3 adults)
2 red-eyed tetras (that will hopefully be finding new homes soon)

ammonia: 0ppm
nitrite: 0ppm
nitrate: 15ppm
GH: 120ppm (as best as I can tell)
KH: 220ppm (as best as I can tell)

Water changes: 15% twice a week

I had three adult cories for several months; all was going well until about 5 weeks ago one of them started listing off to the side, gasping for breath. He obviously was not going to make it, so I euthenized him before he expired and got eaten.

A week later, I could not find a second cory, and never found another trace of him.

Three weeks went by and my remaining cory was happy and healthy. I bought two more baby cories, and all went well for two weeks.

Yesterday, I found my remaining adult cory upside-down and thought he was dead. I took him out and put him in a separate tank where he twirled over and over, gasping for breath just as the first cory had. He died soon after removing him from the big tank. Since this one was an albino, I was able to see that his gills were much too red to be normal, and that one side was more pronounced than the other. I cannot get my photo to attach.

No other fish have taken ill, only the cories. Is this some kind of parasite, like twirling disease? Could it be gill flukes? Are my other fish in danger? Thanks for any suggestions. I know the info given may not be enough for a diagnosis, but just thought I would ask.

Best wishes for your fishes!
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post #2 of 9 Old 03-17-2008, 03:14 PM
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How high is your water line? Cories need to be able to gulp some air into their gut when they don't get enough oxygen from the water itself. So if they can't get to air a few times a day, they'll drown.
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post #3 of 9 Old 03-17-2008, 03:14 PM Thread Starter
Here is my photo - this was taken just before he expired and is actually the better of the two gills. The other one was even more red and swollen. I see also that his tail is slightly shredded.

Best wishes for your fishes!
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post #4 of 9 Old 03-17-2008, 03:17 PM Thread Starter
I didn't know that about cories - I do see them swimming to the top occasionally. The tank is 18 inches deep - as were the two previous tanks all three cories had been in. They were a year or two old, so at least until they took sick the depth of the tank was not interfering with their breathing.

Best wishes for your fishes!
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post #5 of 9 Old 03-17-2008, 05:45 PM
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did you check your water parameters? cories are generally hardy, but some of them are sensitive to ammonia, which might explain the red gills. the shredded tail is a sign that someone is picking on him, so that could stress him out, making them more easily ill.

"Instant gratification takes too long"
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post #6 of 9 Old 03-19-2008, 01:47 AM
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Cories are very sensitive to water environment. I used to have cories together with my tetra. They were a happy bunch until I accidently washed my filter with tap water. (Was blur cause I was sick that day.) The first to die was my cories in 2 days. Signs include the redness in the gills.

I notice that ur Nitrate is around 15ppm...perhaps doing a water change to lower it would be better.
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post #7 of 9 Old 03-19-2008, 10:21 AM Thread Starter
If cories are that sensitive to water conditions, I am sure that is what killed them. I have hard water with a high pH, so I tried mixing bottled water with my tap water - in even quantities to keep the mixed water at a constant pH - but the fish didn't like the new water even though I added the mixed water very gradually. I just gave up after all the fish started hiding in the corners after each water change. Thanks for pointing that out. And I will do more wanter changes to get the nitrates down a little more.

Best wishes for your fishes!
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post #8 of 9 Old 03-19-2008, 08:58 PM
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Some cories are more sensitive than others. There are many wild caught ones that have trouble adapting to aquarium life. However, the kind you have are captive bred, so they should be more flexible. Honestly, your tank parameters are extremely healthy, so I don't think that could be it. My guess would be infection- have you tried QTing them and doing a Melafix/Pimafix regimen?
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post #9 of 9 Old 03-21-2008, 03:21 PM Thread Starter
I think you are right, Okiemavis. Using the mixed water may have caused them stress that ultimately led to illness. If I have any more trouble with my baby cories, I will try Melafix and Pimafix. Appreciate everyone's input!

Best wishes for your fishes!
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