Why Did My Panda Corries Die?

[corradophil]

I have a 125 litre tank, with about 50% plant coverage. This was about 30% when I had the corries, and is gradually increasing.

Amonia - 0ppm
Nitrite - 0ppm
Nitrate - 40ppm

Water temp 25 deg C.

Sand substrate.

Other fish.

5 black neons
4 Cardinal Tetra
3 Zebra Loach
1 Ancistrus (2" long)
1 male & 1 female Boeseman's Rainbowfish
3 Black mollies

In the past I had a group of 8 panda cories. They all seemed fine, but every week or so one cory would go down hill over a day or so and die. Depsite lots of water changes I never got to the bottom of the cause of this and eventually one by one they all died.

I am considering rehoming the mollies as I have learned they need brackish water, even though they were sold as freshwater fish.

I would really like to get some more cories, however I do not want to kill them, so I need to know why the last ones did not survive.

The other fish showed no signs of aggression to the corries, so I assume that was not an issue, and the other fish are in good health.

Could the nitrate level be the problem?

Would I be better off trying different corries instead of pandas?

 

[smegforbrains]

I have always had the same problems keeping Pandas, I can only put it down to my Raphael being hungry.


You could look at Sterbai, Adolfoi or Julii as an alternative.


Don't be too worried about the Mollies, the Brackish Water connection is a common misconception. Wild caught Mollies require Brackish Water, but I doubt very much if the ones you have are wild.

Line bred Mollies are bred in freshwater, hence the reason they are sold as freshwater fish.

 

[Spishkey]

firstly you dont really need to rehome the mollys they can be kept as freshwater too, i have many mollys and they have no salt added to the tank

ok now back to the corys, did they have any symptoms? any sign of bloating/swimming troubles/red gills anything out of the ordinary before they died?
what did you feed them on?

panda corys do better in cooler temperatures (21-24) but i cant see a temp of 25 harming them enough to kill them, so maybe a bacterial infection?. what is the ph of your tank as pandas like a low ph (6-7.5 ish) how long had the tank been cycled before you added the corys?

i had a group of 33 sterbai corys wiped out over a 6 week period. turned out to be dropsy. it shows hardly any symptoms in corys due to them being scaleless. by the time it was diagnosed i managed to save just 4. the only symptom that showed was a swelling just underneath their bodies, it looked like a see through spot!

 

[corradophil]

Ah ok, so the Mollies can stay. Thats good news - thanks.

Are other types of cory such as Sterbai, Adolfoi or Julii more hardy than the panda? The Pandas are the only corries I've had.

Symptoms:

All of them were slightly pink around the gills, but I assumed this was normal colouration.

There was no obvious bloating, or anything looking like a see through spot, but some of them were struggling to swim, one I remember ended up on it's side laying in a plant before slowly dyiing.

The tank was well cycled and established with zero amonia and nitrite.

PH is high in my area at around 8 - 8.2. Is this too high for them to survive in?

I assume the nitrate level is acceptable, so can be discounted as the cause.

 

[smegforbrains]

I also have high PH but the Pandas would have been in a high PH LFS tank anyway, so I doubt this was the cause.


They do seem a lot more fragile than most other Corys I have come across and a lot more susceptible to sudden parameter changes.

 

[corradophil]

I also have high PH but the Pandas would have been in a high PH LFS tank anyway, so I doubt this was the cause.


They do seem a lot more fragile than most other Corys I have come across and a lot more susceptible to sudden parameter changes.

You have just reminded me, they seemed to suffer particularly after water changes.

I may try some different corries and keep a close eye on them.

 

[Kets]

In my opinion, you may want to step up water changes. 40ppm seems a little high

 

[backtotropical]

I'd just like to clear up the apparent confusion about mollies here.

All mollies (not just wild caught varieties) do much better in slightly brackish water. They can be kept in freshwater, and will even breed and be very happy, but in such conditions they are a lot more susceptible to diseases such as fungus and finrot, especially if the water is soft and acidic. They will do better in freshwater if the water is hard and alkaline.

They won't necessarily die in freshwater as these diseases are easily treated, but they certainly thrive in brackish water, as opposed to surviving in freshwater.

Contrary to popular belief, they're not easy fish to keep healthy, and certainly not recommended for a beginner with a freshwater tank.

Cheers

BTT

 

[MHunt]

I had exactly the same problem with pandas, they just kept dying! I think they're just a sensitive bunch!

 

[Inchworm]

Hi corradophil

C. pandas are often more sensitive to water conditions than some of the other corys. When I first started with them I lost them frequently. I eventually found that I could do better with them in a single species tank than I could by keeping them with other fish, even with only corys. From what I seem to see on this forum, more people have trouble keeping them than any other readily available Cory.

Your pH is high, but most fish can adapt unless they have a sudden change. Nitrates are elevated, but many people keep them in higher. The temperature is at the high end of their preferred range, but not too high. Perhaps the problem is the combination of all three.

There are a few other things to think about. What kind of substrate do you have? If you have coarse gravel, potentially harmful bacteria can breed in the debris and/or uneaten food that collect there, especially if your ancistrus is producing a lot of waste.

If you're feeding your ancistrus and loaches fresh vegetables, they can pollute the water quickly. Be sure to keep up water changes and rinse your filter in tank water frequently. If there is a smell about it, this could be the problem.

Do your corys avoid any of their tankmates? They are more timid than most corys and aggression need not be real. If they think they are in danger they will be stressed.

Did you ever test your tap water? Sometimes that can give you a clue about unusual problems.

Yes, there are some less touchy corys, such a C. aeneus. Perhaps you would have more luck with them.

 

[wendywc]

^^^ Very interesting!

I was wondering about cories recently myself, since I've never had them before and have been looking to setup the 55 gallon tank again. In my case since I also want a diverse community, I would go with C. aeneus or C. sterbai instead.

 

[corradophil]

Kets, unfortunately my tap water is around 40ppm, so water changes do not reduce it. I do 25% water changes each week.

Backtotropical, That kind of sums up what I had read elsewhere on here, I think I'll keep them, but keep a close eye on them.

MHunt, They certainly are sensitive!

Inchworm, I have a sand substrate as I beleived this to be best for corries, plus I actually prefer it to gravel. I feed the loaches and ancistrus sinking pellets from the LFS. There is no smell in the tank, but when I rinse the sponges in tank water they have an earthy smell to them - I have always assumed this is normal. All the cories have gone, but I would really like to get them again if I can be sure not to kill them. When I had them they did not appear particularly scared of other fish, and happily sat there whilst other fish were swimming near by. If I do get more I will look at lowering the temperature slightly. The tap water has a high PH, so not much I can do there. I plan on increasing the ammount of plants in the tank, maybe this will help reduce the nitrate level. Great photo of all your pandas there, they are one of my favourites.

wendymc, Corries are a great addition to the tank.

 

[Inchworm]

Hi corradophil

Your tank certainly does sound normal. Since the tap water is similar to the water in your tank, that rules out fluctuating conditions which could be harmful and gives us no clues there. Your filter sounds good too.

Since you mentioned that you have a planted tank, what about CO2? Do you use it? Corys originate in flowing streams and rivers, so lack of sufficiently oxygenated water could cause a failure to thrive. While they have the ability to gulp a bit of air from the surface from time to time, in the long run, they would probably be weakened. Since my tanks are not planted to that extent, I don't have personal experience with it, but it's something to think about.

If you rule out damaged gills from poor water chemistry, most corys die because of bacterial infections of some sort. While potentially harmful bacteria exist in all tanks, all fish build up a natural resistance to them. It's usually when some other factor weakens them, or some new bacteria is introduced to the tank, that their immune systems fail and they become sick.

Since your pH is so high, you will want to watch other conditions that could be hospitable to the growth of harmful bacteria to minimize your risk. Keeping the surface of the water moving to oxygenate the water and lowering the temperature will help with this.

Since they spend much of their time sitting on the bottom, a clean substrate is essential. Also, stir the sand occasionally to avoid the formation of gas pockets. Since corys are fast swimmers and spend time picking at the bottom, a fair amount of open space is needed to keep them successfully.

I hope this helps you figure out what went wrong with your Corys.

 

[corradophil]

Hi Inchworm, I do use CO2, but it is at low levels. I use a mixture of sugar, water and yeast in a coke bottle to produce a little CO2 just to strengthen the plant growth.

Last night I did a water change and have now changed the output pipe from the pump so it produces more water aggitation.

I think I will lower the temp to 24 deg C, closely moniter water conditions and if they appear stable and acceptable I will try some cories again.

Thanks for your input, it is making what I should and shouldn't do for the cories alot clearer in my mind.

 

[tenohfive]

I'm having the same problem at the moment, although they not just with panda's - it seems to be one of the other flavours that seem to be suffering worst.

Its a Rio 180, very overfiltered (2 Eheim externals and a Fluval 4+) but that doesn't seem to affect the flow rate at sand level. Plenty of planting and hiding spaces, mature tank, nitrates of around 40ppm and pH of 8.0 - 8.2. I can't work out why they're dropping but they are doing. Had about 3 corys die so far. Unfortunately I've not seen much signs or symptoms as due to the size and planted nature of the tank, I've only found one within 24 hours and the only thing out of the ordinary I could see was reddening from the gills upwards, though that may be because I found him upside down/on his side.

No CO2 running but I use plant ferts, I added some yesterday after a 40% water change, so wondering if that could have had an effect?