Cories More Sensitive?

[DrgRcr]

I'm wondering if cory species are more sensitive to water parameters than other fish. Here's the scenario. My 72g has been running for 18 months now. It is a community tank with cories, tetras, rainbows, danios and two otos. I started last year with 6 each of Sterbai and Panda cories. I lost a couple within the first month or so, and I believe it may be because the tank was not well established(I did fishless cycle it). But since then, it seems I lose one every 2 months or so. They show no outward signs of disease and they continue feeding. Then they start to become pale over a week or two and die. I did read initially that some had no luck keeping Pandas alive very long. Other than that, all of the other fish have done well. No disease outbreaks at all. Even the otos, who I read were also hard to keep going, have nice fat bellies. I do 50% water changes every week to ten days, depending on my schedule, and the nitrate never goes over 20ppm. I have two theories. The first being that my water has a pH of about 8, GH 9, KH 4. So being a soft water fish, perhaps over time it takes it's toll. The second is that being a bottom dweller, they are feeding and searching among the waste of the others and possibly any disolved organics that settle lower in the water column as well. What are your thoughts?

 

[stephcps]

I have found my cories to be very hardy. I have several sterbai, several albino and numerous bronze as they spawned and I grew out several of the fry. It sounds like your set-up should be ok. The only thing I would maybe question is your stock. What kind of substrate are you using? Did you notice anything with their barbells?

I am far from an expert. I am sure others will chime in.

 

[DrgRcr]

Thanks steph. I'm using 3M colorquartz S-grade as a substrate. I don't think that it is too sharp for them, it is sized like poppy seeds and is very uniform, almost like tiny marbles. Perhaps there is something else in it that is causing them to be ill? But I read alot of good about it before I used it. What concerns you about the other stock? Soft and hard water species together I'm guessing?

 

[ChrisK]

Some species are hardier than others, sounds like you may have just got a bad batch, I've had my best luck with bronze, emerald, and peppered species. At one time I bought 5 pandas, and they all died within 2 month of swim bladder infection.

 

[Ratlova30]

I've had all kinds of cories and they've all done really good. When I first waslearning the ropes of having a fish tank and I didn't know what a water change was the corys were the only fish to survive. The only think I can really think of is lack of food. Even if you put sinking wafers of whatever food doesn't mean all of the other fish arn't eating most of it before the corys get to it. I do agree that the peppered.bronze and albinos seem to be hardier but then again I havn't ever had problems with corys dying off before old age hit them.

 

[stephcps]

I meant the cory stock. I know I have bought fish from LFS before I knew more about what I was doing or wanted really. They don't always get from great sources and don't always care for them well. Maybe they were just kinda weaker in general. I don't know...just a thought since I don't know where you got them from. I do also think Ratlova may have a point about feeding. I have mine with Discus and Angels which I feed heavily a couple times a day. There is no shortage of food on the bottom for them to forage. But, if you are a light feeder, that may be part of the issue. I think your substrate is fine. Lots of people use that type. It does stink to lose fish in general, but they are so fun!! Really one of my faves.

 

[fishycat]

I don't know if the PH is a problem, if you drip-acclimated them when you got them, they should be fine with your tank. IMO it's more stability versus actually trying to keep PH at a certain level.

Are you feeding your cories any sinking wafers? When they were pale, did they have skinny/sunken bellies?

I have a sand substrate and only occasionally swish water around the plants to get the crud up and vacuumed. I don't think their foraging into the "muck" hurts them.

All in all, could be bad stock? Pandas are notorious for dying out.

 

[CornBreadjiffy]

Yes agreed with most that cories are very hardy and will adapt quickly to any water perameter

 

[guppy226]

Corys are normaly very hardy. I think the pandas are one of the less hardy ones thow.

 

[DrgRcr]

Thank you for all of the replies.

Perhaps I did get some weak stock, but LFS I got them from has a good reputation, but certain species are known to be weaker to begin with I guess.

Feeding wise, I know they eat because I feed sinking pellets and flake as well as the occasional veggie wafer. I have always seen them stop and gobble them up when they come across a pellet on the bottom. And I've watched them swarm to a wafer at times.

I really don't know what else to think at this point. Maybe a small trace of heavy metal in my well water which settles lower in the water column? I know I'm grasping at straws, but I'm out of ideas. I think I've already resorted to the fact that it just may be a function of my setup and I probably won't try to keep them again. Eventually, I think I'd like to try some Victorian cichlids in that tank anyway.