Why can't I keep Corys?

[AntyPam]

I have an established peaceful community tank (1 1/2 years) but cannot seem to keep corys alive! I have purchased 5 or 6 Julii corys on three different occasions now, and they don't last for more than six weeks or so - one crew was missing in less than one week.
I do 30 - 40% water changes every two to three weeks. The pH is 7.8, water temperature 78°, nitrate, nitrite and ammonia consistently hovers at 0.0 ppm (I use an AVI Freshwater test kit). I supply the fish with a variety of foods (flake, shrimp and/or algae pellets, brine shrimp or tubifex worms) 5 to 6 times a week.
I've never seen any of the other fish bother the corys, which are my very favorite fish (when they're alive). Everybody gets along. The other fish have been in the tank from the beginning (except loaches added about six months ago). Does anyone else have a problem with corys, or know what else I can test to find the problem? I thought these guys were hardy?

[pinkertd]

If you are purchasing fish store stock, it seems it is their stock. It happens all over. Took me quite a few purchases before I got enough julii's to survive and thrive. Same thing seems to go for the otos making their way into the fish stores. If you can keep them alive a month, you pretty much have long-term survivors. Most die within days/first weeks. I'm even beginning to wonder if they don't drug them with something to catch/dividie/load them to their destination stores!

[OldMan47]

Look at this picture http://www.planetcatfish.com/catelog/image.php?image_id=8990 if it is your fish you have what is called false julii. You are at the extreme top temperature for these guys. If there is salt in your water like there is in far too many tanks then they are being subjected to far too much stress. Your stock doesn't look like it would be a problem for most cories. Is there any other clues you can give us about your tanks?

[AntyPam]

Yes, this guy looks just like the ones I've purchased. The temperature range is usually up to 78° but I wonder about the pH being too high? I have lots of wood in the tank. I don't ever add salt, and would think water changes would remove whatever salt enters the tank with food. What's a healthy way to bring the pH down? Are there other corys that would fare better?

[KarlTh]

GH? Single most significant stat for matching fish to water. pH doesn't matter.

[AntyPam]

Translate 'GH' please?

[fishorama]

When we tried keeping red tailed or rainbow sharks together with corys the poor corys were eventually killed, body slammed into the gravel. Sharks are territorial & corys don't understand.

What kind of loaches do you have? Except kuhlis, most can outcompete corys for food. They can also be too "frisky" & some are territorial.

GH is general hardness given in ppm or German degrees of hardness, ppm/17.9.

[pinkertd]

Your ph is fine, mine are in 7.6. It's not your temperature, my shoal is in my warm discus tank and have been for quite some time. They were recommended to me by discus people who had kept them happily in higher temps....as well as rummy nose tetras and cardinal tetras and albino cories which data usually also states an upper limit for these fish at 78-79F.

[jpappy789]

general hardness...the amount of dissolved minerals in the water, mainly calcium and magnesium

good cory stock is sometimes harder to find.

[AntyPam]

They're coolie (kuhli) loaches. I've never seen a water hardness kit - how would one test this? And what is the range of acceptable hardness for the corys?

[Barbie]

gH is the general hardness, or total dissolved solids in your water. It interferes with osmoregulation, while pH tends to just affect how toxic ammonia is (overly simplified, I realize). Loaches are going to be big competition for cories, so I would definitely recommend a quarantine period for any cories you buy in the future. They're going to need time to acclimate and recondition after their long trip to you. Trying a species like C. sterbai that tolerates higher temperatures might also help your success rate.

Messing with your pH is a BAD idea. More people kill their fish trying to modify their pH and causing it to bounce than they'd ever lose in acclimating them to what comes out of their tap. If you drive the pH down with an acidifying product, the alkalinity of your water will then pull it back up to the level it's buffering to. Then because it came back up, people dump in more and cause it to happen again. It's VERY stressful for the fish. Stability is a much better idea. Rather than add anything, do more water changes.

Unless that tank is heavily planted, your nitrate test kit is bad. I'd be willing to bet your nitrates are 40ppm or more with water changes every two to three weeks. Changing 30% of the water weekly will definitely do more to stabilize your conditions in a way that's beneficial to your cories. Also, you don't mention your substrate. Is it sharp edged or smooth? Cories tend to suffer from barbel erosion if they have to sort around in substrate that's got any sharp edges. They are then more susceptible to secondary bacterial infections.

Your red tail black shark is also going to become more territorial as he ages and terrorize your bottom dwellers. Where it seems you prefer cats and loaches, you might rethink having him in there long term.

Barbie

[jpappy789]

Very well said barbie :)

I agree with her 110%

[Lupin]

Very well said barbie :)

I agree with her 110%
What he said.:lol:

It might be worth noting how long the stocks have been in the LFS. Fish become severely stressed depending on how they were handled by packaging and travel.

[AntyPam]

Thanks for taking the time to explain so much, Barbie. While not what I would call heavily planted, I do have many live plants and some large mopani driftwood pieces. The substrate is smooth gravel and stones so I don't think that's a problem. My LFS told me they have experienced difficulty with entire shipments of corys, so it may be I'm having problems because they were shipped poorly to begin with. Unfortunately, the loaches do SUCH a great job keeping the bottom of the tank clean, I never see any traces of the corys once they've 'disappeared' . . . Lastly, the shark chases the loaches like crazy, so he's not long for the tank - you're right, I much prefer the corys and loaches over him!

[jpappy789]

Seem like you've found the problem. Corys do not travel well, whether it be to the LFS or just to your home, but once they get acclimated to the tank they do very well :)