HELP! My Cory Pandas are dying one by one.

[A649475]

Hi everyone,

Last week I bought 4 corydoras panda to my 20H gallon along with 8 rummynose tetras and 1 honey gourami in addition to 6 cardinals that I previously had. The cardinals have been with me for at least a year. All the fish are doing well. However, one of my corys died yesterday and today I found another one dead. I looked for the other two left in the tank and one of them is in pretty bad shape. When I bought them, they seemed fine and very active.

I didn't notice anything unusual on the two corys that died. But, the one that's in pretty bad shape, I can see some blood around his bottom fins and around the gills. He can barely swim using his tail, but he isn't using his side/bottom fins. So I'm guessing he injured himself pretty bad.

I posted some pictures that I took right after I got the dead cory out and a side shot of the cory that's injured.

I did a water change this weekend. I dechlorinated my water. Ammonia and nitrites are 0ppm. Nitrates in my tank never goes above 5.0ppm. My substrate is eco-complete mixed with some black petco gravel. There is driftwood in my tank as well. Water is being filtered by AC70. No C02, ferts every week, planted with a lot of java ferns and melon sword.

So the big question is, why are my corys dying? And what caused those nasty injuries in my panda? The driftwood? The gravel?

I'm looking at changing the gravel to something finer or maybe just plain Eco-complete without the gravel.

 

[tanker]

That is not a Panda, it is a Corydorus Metae. How did you aclimate them?? How long have they been at the LFS??

Not the cause but that gravel looks too big for corys.

 

[Fozzybear]

My corys really enjoy a smooth substrate, and I've also come across literature in my research commenting that cory's require pristine substrate maintenance to prevent damage/infection to their barbels. How frequently do you water change? do you gravel vac? +1 to tanker's question to "how long have they been at the LFS??" as you may have purchased pre-diseased fish. I've seen my LFS keep corys in pretty horrible conditions. I hope you get them healthy, and also...AFTER you have this whole situation figured out (assuming you still have 1 or 2 corys left) you're going to want to get them back up to a school of 6+ (hopefully healthy, disease free, fish) as your poor remaining cory will die of the stress of being left alone regardless of whether or not you get him healthy.

 

[A649475]

I followed this article to acclimate my fish http://www.aquariumpros.com/articles/acclimation.shtml.

I'm not sure how long they have been at the LFS, maybe a month or longer? I go there once every two months or so. They always seem to carry corys. I was just told these were pandas. I didn't really notice the difference until just now.

I don't vacuum my substrate anymore due to all the plants that I have. Should I start doing so? I thought all the debris and mulm was beneficial for the plants. Plus I don't see any problem with my nitrates.

Should I get a new substrate? Any recommendations?

 

[rufioman]

I drip most freshwater fish I buy. I would get pool filter sand and make sure that once properly acclimated the tank is setup to house corys in addition to your other fish. Good luck!

:cheers:

 

[Fozzybear]

I'd definitely vacuum, In my tank i allow mulm to accumulate immediately around plants but keep the majority of the substrate very very clean. At least twice a week i stir things up to allow the filter to pick up any debris and do weekly vacuuming. I can't tell by your picture but do your fish have any barbels at all? if not then you might be looking at an infection, also, what are your nitrates? high nitrates can cause barbel/mouth infections.

 

[tanker]

You do not have to do "deep" gravel vacs, just vac down about 1/2 inch or so. Food maybe trapped in the gaps and spoil.

 

[OliviaBolivia]

I had a similar problem with panda corydoras dying one by one a while back - but I'd had mine for some time. They were being bullied by loaches and sadly, starved to death. I now have 2 pandas and 3 julii's, and no loaches.

Because you only got yours last week, my initial feeling is that they were already in poor shape at the LFS, and the shock of the move just tipped them over the edge. It's unlikely that your gravel, whilst not really ideal for corys (they could wear out their barbels on it, and although not life threatening, this increases the likelihood of infection), could have finished them off in a matter of days.

What about the temperature of the water.....corydoras seem to prefer the cooler end of the spectrum? And they also prefer softer water with a low to neutral pH?

 

[A649475]

I would assume my water is soft since there is a huge chunk of driftwood in there. My nitrates as I said before are always under 5ppm.

I'll start gravel vacuuming. I have one of those electric gravel vacs so it's not a tedious task. I just ordered Eco-complete online to replace the mix of gravel/Eco-complete that I have now.

I placed the injured cory in a quarantined tank. The one left in my main tank is pretty lethargic, sitting in one corner all the time. Both of them aren't eating as far as I can tell. I tried hikari sinking wafers, carnovire sinking wafers, tetra algae wafers, and the regular tetra flakes. But they aren't accepting any of it. I have some hikari bloodworms, tubifex, and flakes from other companies, but I haven't tried with those yet.

Any recommendations? I'm still baffled at how my third cory got that nasty injury. Any guesses?

 

[A649475]

UPDATE


The injured cory recovered successfully although he swims rather slowly and the other cory seems just fine.

I changed my substrate to Eco-Complete. The grain size is smaller than the one I had a couple of years ago, which I don't mind.

I added 4 panda corys as I couldn't find the cordydoras metae in my LFS anymore. They seem happy and all of them are getting hikari food (sinking disks and carnivore sinking bites) along with the flake food that hits the bottom.



One hypothesis that I have regarding the injuries is that the way I had my tank set up before, there was a gap/cave underneath the driftwood. I think the cory got stuck there and injured himself. The point of it was to give the fish a hiding place. This time I made sure there was no gap/cave in between the driftwood and the gravel. No injuries thus far. And addressing the other corydoras that died, I believe I did indeed get already weakened corydoras that only died because of the stress of adapting to a new environment.



PS. Finished reading "The Ecology of Aquarium Plants" by Diana Walstad and in agreement with the author, I believe that there is no point in vacuuming the substrate in a well established planted tank. I never had an issue with high levels of nitrates in this tank. In fact, I have trouble keeping nitrates up and my plants from starving.