Craig-D

I first got panda cories about 2 months ago. They've been fine until the last week or 2. I've lost 3 pandy cory catfish in the last 2 weeks. A fourth is about to go any time now. The remaining 3 are fine (for now). They always go the same way: one day they're fine, the next thing you know they are breathing rapidly and don't eat. Then they just sit motionless until they pass on. It's one after another. I can't explain it.

My water parameters: ammonia & nitrite 0, nitrate 10-20 PPM, pH 7.3, temp 77 degrees F

The tank has been up since June 4th. It's a 12 gallon Marineland Eclipse. It was cycled with TSS before the cories were added. Other tankmates: two platies and 1 betta (he is not aggressive, he's been fine with the 2 platies for months before moving to this tank.). They are fed the typical assortment of flakes, freeze-dried bloodworms and pellets, with sinking stuff for the cories.

Maintenance procedures: weekly 25-30% water changes. Weekly gravel vacuum, monthly filter media & carbon change (does not cause mini-cycle as most bacteria are on bio-wheel).

Any suggestions are helpful, as at I'm at a loss here. My research has turned up nothing other than others seem to lose cories at an alarming rate too for unexplained reasons.

hssea

It might be a mini-cycle when you are replacing the filter media. Alot of people here just rinse (in old aquarium water) their filter media...it does contain alot of beneficial bacteria. Also the list of fish appears to be overstocked

MizRamzi

With a 12g tank removing a gallon or 2 for wc would be sufficient. 20/30% is too much.
What type of substrate are you using? How many times a day are you feeding? I do know that Panda Corys do best in a well established tank. Ditto on what hssea says.

jdhef

It sounds like you are a little overstocked for a 12 gallon tank. It could be that your Betta is picking on your cories (mine was, so I had to move him out). Cories can be pretty sensitive to water conditions.

Make sure you really shake and pound on Nitrate bottle #2. If not shaken really well, you can get a false reading on the nitrates. With you being a bit overstocked, I wouldn't be surprized to see your nitrates getting sorta high.

Additionally, if you don't have an airstone in your tank, you may want try adding one. There may not be enough oxygen in the water to support your fish.

Good Luck

Craig-D

Another of my pandas just died. I am now down to 3. Thanks for the suggestions guys. I'll respond to each.

There is no mini-cycle when I replace the filter. Ammonia remains 0 because most of the bacteria is on the bio-wheel which is never changed.

The tank is not overstocked. The betta is 2", one platy is a fully-grown 1.5", and the other is a balloon platy that has maxed out at 1". The 6 cories are (were) all 1" and have a small bio-load. All water parameters consistently remained within acceptable levels with this stocking level.

I use small, smooth, rounded gravel as substrate, which along with sand was is recommended for cories. I feed once a day.

As stated in my initial post, my water conditions are immaculate. That is not the cause of this. My nitrates are consistently in the 10-20 ppm range and I'm aware of how to handle the nitrate test liquids. Though this tank is new, I'm not new at fish-keeping. There's definitely something I'm missing here, but I don't think it's the typical newbie mistake.

I considered the possiblity of low oxygen, but I doubt it. The pandas would be constantly going to the surfce for air if that were the case and they don't do that. The filter is rated at 150 GPH, which mean it's turning over all the water in the tank every 4-5minutes or so. Aeration should be fine.

MizRamzi

I asked about substrate cause gasses can sometimes build up beneath finer grained. When vacuuming these gasses can be released undetected. Maybe you just have a bad batch of corys. But I do again state that Panda Cory's need a very well established tank, preferably a planted one.
I'm sorry for your losses, it's hard I know.

Shawnie

im also sorry for your losses

Im going to suggest something that aquarist and I read last week...are you using amquel+ with your water changes? the reason I ask is that amquel products are also dye removers...meaning you could be getting a false negative reading for ammonia / nitrites when using the API test kit with amquel...although I agree you do have bacteria on your bio wheels, theres much controversy on if biowheels actually have the "most" bacteria so changing out the filter media could in fact be too much...I dont think the water change is too much tho as there is very little free floating bacteria...

as every one else, these are suggestions not something we are saying is happening ...people give advice and no one ever said a thing about you being a "beginner fish keeper" I hope things work out better!

harpua2002

I'm going to respectfully disagree here. The only time that this would be detrimental to the fish is with a case of "old tank syndrome", where not enough maintenance takes place. In those cases, the fish become used to water with a high level of nitrate and dissolved organics. When this happens, large water changes cause a quick shift in parameters and will kill fish. For a tank that is properly maintained, large water changes are no problem. I change 3-4 gallons out of my 8 gallon every week, and 60+ gallons out of the 120, for example. My fish don't mind at all; in fact, they are more colorful and active following a 50-60% water change. Massive water changes are an important part of my maintenance routine whether the tank is large or small.

Craig-D, your water change schedule is just fine IMO, and your tank clearly is not going to exhibit problems with "old tank syndrome." Your parameters are good and I would agree that you are not overstocked. Gas buildup seems unlikely to me (this is a really overrated phenomenon in aquaria IMO; I've been using sand for years and never had it happen, and only read about a handful of actual cases). I remember reading before in your posts that you change the cartridges every month. While I do think that the Biowheel houses a decent bit of bacteria, along with your substrate and other surfaces in the tank, I also think that you're changing the media too often. Carbon will only become inactive; it will not leach out toxins (I don't even use it and toxins haven't killed my fish ), so it's perfectly safe to just rinse the cartridge in old tank water. Maybe the frequent change in media prevents your tank from becoming really established? If you're set on changing the cartridges anyway, I'd suggest putting some filter floss, ceramic rings, or other media into your filter along with the cartridge- something you can rinse in tank water rather than swapping out monthly.

Finally, I've not had any luck personally with panda cories. I've never kept them at home, but when I was ordering all the FW at my friend's shop, they are one of the species that never did well when they came in. They tend to ship poorly IME and are difficult to acclimate. Maybe you just got a bad batch.

ABCDemily

I agree with Harpua.

I adore Pandas, however I do believe that they are one of the harder cory kinds to keep due to their sensitive nature. Also, I support the 'bad batch' theory, as this is such a high-demand breed, they have probably been over-bred to the end of the earth and back for those specific characteristics.

I'm very sorry about your fishy losses, good luck witht the rest of the tank

Craig-D

Thanks guys, I appreciate the support. Sorry I took so long to respond. I was away on business.

Shawnie, I do not use Amquel+ with every water change. I have it in case of problems, but I use NovAqua+ by itself as my weekly water conditioner. I am aware of Amquel's problems with tests. The website specifically states it is not compatible with the API test, so I keep that in mind when using Amquel.

Harpua, you and Shawnie made a good observation about my filter change schedule. However, I test daily for awhile after each media change to make sure there are no problems and there have been none. I maintain my cycle each time. I don't know if you guys are familiar with the Marineland Eclipse system, but it really does require a media change each month for optimum performance. The media lays horizontally in the hood and after a month's time the water starts going over the media instead of through it, thus rendering it ineffective. Also, the flow rate decreases notably. Rinsing the media and reusing it does not stop this - I tried. I have two pieces of sponge media in there from my smaller hospital tank that I never remove (to keep them ready if that tank needs to be used). So there is media in there that is never changed in addition to the bio-wheel.

I think all of you guys are right that Panda's are just tougher than average to keep. Knowing that makes me feel better that it wasn't something I did. I can happily report that my 3 surviving ones are doing fine and thriving. So I do now think the others were just a bad batch. I'm going to replace my losses by getting one more Panda for an even 4, plus a couple of Endler's. That will be it for my tank stocking going forward.

Butterfly

I personally wouldn't add the Endlers. They are small, colorful and fast... the perfect Betta toy. Since they would be swimming at the Bettas level and will be something new the betta is more likely to object to them.
Carol

Craig-D

You make a very good point. I thought about that as well. But my betta is very mellow, and in a 1.5 years of ownership he has never attempted to harm another small tankmate. When my wagtail platy was young & tiny he left her alone. Really small fish like fry are the exception - they are dead meat with him. He actually plays with his tankmates in the filter current. I think it'll be okay, especially as he has no chance of ever actually catching an Endler's even if he wanted to. I would never put guppies or gouramis in there with him because of the known incompatabilities, but I think Endler's will be okay. I'm willing to risk it because my options are few with my current resident compatibility, tank size, and water parameters. There aren't too many non-schooling fish out there that stay small enough to avoid creating a bio-load too high for my tank.

Craig-D

Just lost yet another panda cory. This one to internal bleeding that I first noticed yesterday. I know others have reported similar problems with panda cories on here, but this is getting ridiculous. I refuse to give up though. I love the little buggers. I'll stick with just the 3 I have left for now though.

Oh, and Butterfly, I didn't get Endler's. I got some cardinal tetras instead because my LFS would only sell Endler's in male/female pairs and I don't have room for the inevitable breeding. My betta chased the tetras around for a few seconds when I first introduced them to the tank, but now ignores them. We'll see how that goes.