Dying Corys--Help!

[DavidB]

Greetings and Happy New Year from a new member!

Here's the problem: I have introduced 6 Panda Cory's in the last week and lost 3 of them. 2 other, older corys (albino) also died a few weeks prior. Tested the water for nitrates, nitrites, ammonia, all negative. No other fish lost (mostly tetras and other mid-strata fish).

Noticed tiny black worms in gravel that came up in net when I retrieved the dead corys. Local fish shop said it's a sign of dirty gravel; worms probably were an "after-the-fact" thing--i.e., not the cause of the dead corys, but came to scavenge body.

I have been vacuuming the gravel every other week for about a month; before that, the gravel was DISGUSTINGLY dirty, with a huge algeal bloom due to tank neglect (a long story for another post!).

Question: what's killing my corys? Is the gravel harboring nasties left over from the extended time of neglect? If so, should I take down the tank, replace gravel?

(Note: was careful introducing new corys to tank--put bag in tank, added a bit of my own tank water to bag each 20 minutes, did that over a few hours, then added stress coat to tank, etc.)

Thanks for any suggestions....and congrats on a great looking board!

David

[Matt W]

OrionGirl once told me:

"Cories are very poor shippers, in general. Many times, they are shipped with pure 02 pumped in the bag, and since they surface to gulp air, this can actually burn their gills. I don't buy cories until they've been at the LFS for at least a week. My LFS recently had a shipment of skunks come in--the whole lot died within 4 days."

I've followed that advice since and haven't had a cory pass away on me...

[JackDonkey]

I bought 10 cory arcutaus, 5 from 1 store and 5 from another. They slowly died off about 1 every 4 days until I was down to 3. Those 3 lived for a year and then I had 1 that soldiered on with some other species of cories for a lifespan of about 3 years. I don't have much luck with cories I guess, I had a leucomelas live for about 6 or 7 years though, the last arcutaus was his buddy. I don't think any of my cories died to diesease, and plenty of times the nitrates (and co2, during my early plant days) were a little on the high side. Must have been an issue related to the supplier if they were wild caught like gil flukes or whatever other types of parasites there are, but I don't know for sure.

[DavidB]

Thanks for the replies--sounds like it just may be cory's somewhat fragile state after shipping, rather than any problem with tank.