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When I first started keeping fish, corys were my first fish. I had bronze corys first, then, later, peppered corys. Since I didn't really know what I was doing back then, the bronzies weren't a huge success, although it's amazing they lived as long as they did considering how I treated them. The peppered corys were a HUGE success, even though, or perhaps because of, the appalling conditions they sometimes had to survive (multiple cycling tanks, filter disasters, overstocking, etc...)

Anyway, since I found this site and actually learnt how to look after fish properly, I have had NO LUCK with corys. A few years ago I bought a shoal of beautiful little Panda corys from a large aquarium store. They were in perfect health when I got them, but not long after I introduced them to my tank they began to shows signs of gill flukes. I treated them and thought they had recovered, but shortly afterwards they died of finrot and fungus. More recently, I bought a shoal of - again perfectly healthy-looking - peppered corys from my local pet store and EXACTLY THE SAME THING happened! :cry:

My tank is 15 gallons, with a gravel substrate, a heap of plants, and very gentle homemade filtration using an airstone and some filter wool. There are also two pieces of driftwood which I collected many years ago. Not surprisingly, since they aren't real bogwood they are starting to disintegrate after so long in the water, but they still provide a good anchorage for my Java Fern. The pH is acidic but not wildly so (when I put the indicator fluid in the phial the color is a slightly greenish yellow.) I can't afford a hardness test kit so I don't know the kH but it's probably quite soft, if the water is that acid. The tank's been set up for over 2 years and is thoroughly mature.

I can't understand what's wrong. The only thing I can think of is that the gravel is quite full of detritus and since corys are bottomfeeders maybe that's making them sick. I siphon off as much of the muck as I can every week, but I don't have a gravel vacuum so there's a limit to how clean I can actually make it. When you stir up a bit of the gravel heaps of detritus comes out.

I have kept other fish species in this tank without any trouble; for some reason I just seem to suck at keeping corys! I'd really appreciate it if anyone could give me an idea of why I can't seem to keep them alive. I miss corys :(
 

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Sorry for your loss. I know how atttached we can get to the little guys :-(

I'm sure others with more experence will come in and give you better advice than me, but here is my take. Corys are a scaleless fish, so water contaminants, copper, and above normal levels of thing like amonia REALLY get to them. Also, gravel can hurt their little barbles and once they wear them down, they don't grow back! Between that and the dirtiness of the gravel, you might consider changing out the substrate to sand (stay away from pfs as it's too corse! Not sure about play sand as I've never had it, but be warned that it takes FOREVER to clean). You can also make a homemade vacume using a Coke bottle and a piece of air tubing. Googing diy gravel vacume should bring up instructions on how to do it. ;-)

If you can't change out the substrate quite yet, you can do a bit of cleaning using a turkey baster. I got one from Dollar Tree and you would be surprised how handy it is!
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When I first started keeping fish, corys were my first fish. I had bronze corys first, then, later, peppered corys. Since I didn't really know what I was doing back then, the bronzies weren't a huge success, although it's amazing they lived as long as they did considering how I treated them. The peppered corys were a HUGE success, even though, or perhaps because of, the appalling conditions they sometimes had to survive (multiple cycling tanks, filter disasters, overstocking, etc...)

Anyway, since I found this site and actually learnt how to look after fish properly, I have had NO LUCK with corys. A few years ago I bought a shoal of beautiful little Panda corys from a large aquarium store. They were in perfect health when I got them, but not long after I introduced them to my tank they began to shows signs of gill flukes. I treated them and thought they had recovered, but shortly afterwards they died of finrot and fungus. More recently, I bought a shoal of - again perfectly healthy-looking - peppered corys from my local pet store and EXACTLY THE SAME THING happened! :cry:

My tank is 15 gallons, with a gravel substrate, a heap of plants, and very gentle homemade filtration using an airstone and some filter wool. There are also two pieces of driftwood which I collected many years ago. Not surprisingly, since they aren't real bogwood they are starting to disintegrate after so long in the water, but they still provide a good anchorage for my Java Fern. The pH is acidic but not wildly so (when I put the indicator fluid in the phial the color is a slightly greenish yellow.) I can't afford a hardness test kit so I don't know the kH but it's probably quite soft, if the water is that acid. The tank's been set up for over 2 years and is thoroughly mature.

I can't understand what's wrong. The only thing I can think of is that the gravel is quite full of detritus and since corys are bottomfeeders maybe that's making them sick. I siphon off as much of the muck as I can every week, but I don't have a gravel vacuum so there's a limit to how clean I can actually make it. When you stir up a bit of the gravel heaps of detritus comes out.

I have kept other fish species in this tank without any trouble; for some reason I just seem to suck at keeping corys! I'd really appreciate it if anyone could give me an idea of why I can't seem to keep them alive. I miss corys :(
My odds of being right are slim to none but I added a piece of wood collected from a local lake a week before adding a pleco and new plants. For almost 4 months I chased imaginary water problems and parasites as my fish were glancing. I blamed the pleco and the plants. My wife reminded me about the driftwood 3 days ago so I removed the wood and have not seen glancing in 3 days for the fist time in 3 1/2 months. Knock on wood, no pun intended. Maybe your wild caught wood is the culprit.
 

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How long after you bought your cories did they get sick? Sometimes "perfectly healthy" fish bought aren't perfectly healthy after all. Also, how many did you buy?
 

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Sorry to hear you are having so many problems keeping corys. From the information given, I would think the issue is with the amount of nitrogen compounds (Ammonia or Nitrate) in your tank. Try taking it to a LFS to see if they will test Ammonia, Nitrate, pH and your hardness (KH and GH). It behooves a store to test your water for free. These other water characteristics are good to know but are likely not the problem because of the wide range of conditions that Corys can be kept.

The visible detritus is what I am keying on as the issue. When you do a water change, you need to remove the debris or you could have a build up of ammonia or nitrate. Ammonia is far more toxic and when it is present in a just a small amount it can stress a fish leaving it susceptible to disease or kill the fish in a short period of time. Nitrate will also stress and kill fish but it take much higher levels.

I think some people get stuck on the idea that they are doing a certain percent water change and do not think about what they are trying to accomplish with the water change. Ilook at it as...

Over a period of time, the amount of Nitrogen (ammonia and or nitrate) removed needs to be greater than or equal to the amount of Nitrogen introduced to the aquarium and the more frequent the water change the smaller the spike of Nitrogen compounds.
 

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You could of gotten a bad batch of cory's also. I bought 4 panda's once and they all died in 2 days. When I went back to where I got them all theirs had died too.
 

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Corys are portrayed as hearty fish in many circles and they are given the proper conditions. My experience has been that they are very sensitive to change in water parameters. After having very mixed results, I have discovered that doing a 50% water change right before adding them to the tank has worked like a charm.
 

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Corys are portrayed as hearty fish in many circles and they are given the proper conditions. My experience has been that they are very sensitive to change in water parameters. After having very mixed results, I have discovered that doing a 50% water change right before adding them to the tank has worked like a charm.
I wil have to try that next time I get more! anything that helps is worth a try :-D
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Discussion Starter #9
My odds of being right are slim to none but I added a piece of wood collected from a local lake a week before adding a pleco and new plants. For almost 4 months I chased imaginary water problems and parasites as my fish were glancing. I blamed the pleco and the plants. My wife reminded me about the driftwood 3 days ago so I removed the wood and have not seen glancing in 3 days for the fist time in 3 1/2 months. Knock on wood, no pun intended. Maybe your wild caught wood is the culprit.
I have wondered about this myself, but I boiled the wood extensively when I first collected it and would have thought that would kill anything that might be a problem?
 

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I have wondered about this myself, but I boiled the wood extensively when I first collected it and would have thought that would kill anything that might be a problem?
IMO, I think the boiling is too kill any living thing in or on the wood. However, there may be metals or minerals in the wood that can cause problems, that boiling may not remove. Just a thought, I could be wrong. P.S. What were the signs of flukes that you saw?
 

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Discussion Starter #11
IMO, I think the boiling is too kill any living thing in or on the wood. However, there may be metals or minerals in the wood that can cause problems, that boiling may not remove. Just a thought, I could be wrong. P.S. What were the signs of flukes that you saw?
scratching gills on things, really fast breathing, general weakness and disorientation...also more freqent going up to the surface for airl, I think.
 

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Discussion Starter #12 (Edited)
How long after you bought your cories did they get sick? Sometimes "perfectly healthy" fish bought aren't perfectly healthy after all. Also, how many did you buy?
The first time I think I got three or four (the pandas); can't remember how many peppereds, but probably a similar number. I can't remember exactly how long it was before they started to seem ill, but not very long, probably only a few days?
It's worth noting that when I first got the pandas I was in the process of setting up a new tank (which wasn't yet cycled, so I'm sure that didn't help!) and at first they were kept in a much smaller (6 gallon) tank while I waited for the new tank to settle down. They only started to show signs of illness once I added them to the new tank. But the peppered corys were added much more recently when the tank was cycled, and they got sick too...
 

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Discussion Starter #13
Sorry to hear you are having so many problems keeping corys. From the information given, I would think the issue is with the amount of nitrogen compounds (Ammonia or Nitrate) in your tank. Try taking it to a LFS to see if they will test Ammonia, Nitrate, pH and your hardness (KH and GH). It behooves a store to test your water for free. These other water characteristics are good to know but are likely not the problem because of the wide range of conditions that Corys can be kept.

The visible detritus is what I am keying on as the issue. When you do a water change, you need to remove the debris or you could have a build up of ammonia or nitrate. Ammonia is far more toxic and when it is present in a just a small amount it can stress a fish leaving it susceptible to disease or kill the fish in a short period of time. Nitrate will also stress and kill fish but it take much higher levels.

I think some people get stuck on the idea that they are doing a certain percent water change and do not think about what they are trying to accomplish with the water change. Ilook at it as...

Over a period of time, the amount of Nitrogen (ammonia and or nitrate) removed needs to be greater than or equal to the amount of Nitrogen introduced to the aquarium and the more frequent the water change the smaller the spike of Nitrogen compounds.
I have a pH test kit and regularly test the pH, although I don't have a kH or ammonia/nitrite/nitrate test kit. The pH seems to stay constant at a slightly acid pH. I did buy one of those dip-strips for testing ammonia etc. and although I know they're famously inaccurate, it showed zero of any of those toxins when I tested the water! I asked people on here about this and they thought it was possibly due to the large number of plants (and algae!) in my tank using up all the nitrate.

I definitely need to get a gravel vacuum, or make one, to clean properly.
 

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Discussion Starter #14
You could of gotten a bad batch of cory's also. I bought 4 panda's once and they all died in 2 days. When I went back to where I got them all theirs had died too.
That seems an unlikely coincidence, since this has hapened twice, at very different times, with different species form different shops!
 

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Discussion Starter #16
Corys are portrayed as hearty fish in many circles and they are given the proper conditions. My experience has been that they are very sensitive to change in water parameters. After having very mixed results, I have discovered that doing a 50% water change right before adding them to the tank has worked like a charm.
thanks for the tip, I'll give it a try if I ever get corys again. Yes, they do seem to be very sensitive to anything being slightly wrong in their environment. But what I don't understand is how the pair of peppered corys I had all those years ago managed to live for three years or so without ever getting seriously sick. I transferred them from different tanks constantly, so they had to experience the whole cycling thing multiple times, put up with all kinds of tankmates and water parameters, and most of the tanks I kept them in were much too small, as well! Plus they were the only fish that survived a disaster where a filter that had been turned off for a week blasted toxic goop into the tank (stuff had been rotting in it, ew!).
I can't reconcile that with my experience of keeping corys ever since then...
 

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Discussion Starter #17
These are symptoms of ammonia poisoning.
A revelation! :-D thanks for telling me. What I don't quite understand is how all my other fish have remained so healthy. However, I know corys are super-sensitive and might react badly to a lower level of ammonia than other fish..
It may well be that at the time I was trying to keep these corys I was also being a bit lazy with water changes. If that is the case, then we have an explanation! I've only been really strict with weekly water changes more recently, I'm ashamed to admit :oops:
I'd still like to know if the dirty gravel could be a contributing factor, though. I've noticed that the two cherry barbs I've had for the longest seem to have lost their barbels. They don't seem bothered, although one of them also has rather torn fins which aren't rotting the way they would with fin-rot, but aren't growing back. I wonder if this could have something to do with the gravel...
 

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It is possible for a aquariums bacteria levels to crash. Introduce large amounts of Nitrogen and then drastically reduce the Nitrogen inputs. Similar to the famous ecology example of the fox and rabbit populations being interdependent.

Some fish are more sensitive to ammonia then others. Cory barbels will fall off with ammonia present at some pretty low levels; varies by species.

I went 10+ years keeping fish before I was serious about water quality and changes. :) I have seen a lot of hurt and have seen many others do the same. Cleaning tanks frequently is definitely not the norm in the hobby.
 

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Discussion Starter #19
It is possible for a aquariums bacteria levels to crash. Introduce large amounts of Nitrogen and then drastically reduce the Nitrogen inputs. Similar to the famous ecology example of the fox and rabbit populations being interdependent.

Some fish are more sensitive to ammonia then others. Cory barbels will fall off with ammonia present at some pretty low levels; varies by species.

I went 10+ years keeping fish before I was serious about water quality and changes. :) I have seen a lot of hurt and have seen many others do the same. Cleaning tanks frequently is definitely not the norm in the hobby.
Good to know I'm not the only one lol! I was about to say, you'd think with 7 years experience I would have learnt by now lol.
 

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To start, if your tank was setup for over two years but had not fish in it then it'll lose its cycle. It needs constant fish inside of it, or if it doesn't have constant fish it'll lose its cycle.

Spend $10 and get a gravel vac and do a 50% water change weekly for a month with the gravel vac (assuming you have no fish).

Also, while corrie are schooling fish, try getting 2 and then wait a month and get 2 more. Or you can get all all 6, but dose prime daily for a month to remove cycling issues.
 
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