Cories keep dying on me.....what gives??

[southpaw]

Last Saturday I bought fish for my newly cycled 55g tank (long fishless cycle with ammonia) I ended up getting 10 bleeding hearts, 10 bloodfin tetras and 8 False Julii cories. By Monday I had lost 1 bleeding heart,1 bloodfin and 2 cories. I figured I might lose a tetra or two just because of the stress factor.I went back to the LFS to get them replaced Tuesday...I got 2 more cories and used the store credit for the bloodfin and bleeding heart toward the purchase of 2 GBR's.(I figure a school of 9 each was plenty for the tetras)

Since adding the 2 new cories Tuesday evening I have lost 3 more of them the newest being this morning when I went to do a water change and noticed one dead. This makes a total of 5 I have lost (2 replaced and 3 new deaths)

Are cories this sensative?? Or have I just been getting a bad batch of them??

Here is my stocking as of now and my water perimeters before I did a 50% water change this morning... I am using Prime to condition the water (dosing straight to tank for the 55g volume)

9 Bloodfins
9 Bleeding Hearts
5 False Jullii Cories
2 GBR's

Ammonia: 0
Nirite: 0
Nitrate: 20 (was at 10 when I first stocked them)
pH: 7.6
temp: 79

I have a 2 week guarantee at the LFS so I will wait until later on in the week to replace the cories I have lost just incase I end up losing more. Plus it is a 45 minute drive and I dont want to run up there every time 1 fish dies.

 

[Carp37]

Corys are normally pretty hardy if you get good stock to start with, but I'm REALLY picky about which I buy because they often come in to aquarium shops in shocking condition, and many don't recover from this. If they have red colouring round their gills, look emaciated or have damaged barbels, or even are just too hyper OR too still, I won't touch them. If the ones you're buying look really healthy and your (not so) LFS are having no problems with their stock, the only thing I can suggest is that your water's different to theirs- hardness, pH or temperature- you could call them and ask what their water parameters are?

 

[shaggbark]

hmmm....they are really hardy, I would try another store!

 

[southpaw]

Thanks Carp37 for your input....

They all seemed fine at the LFS but I didnt give them a real good look as there were about 20+ in the tank they came from along with other fish aswell so they were all pretty much in a big pile along the bottom of the tank.

Mine seem to have hyper periods at time running up and down the glass in packs of two or three but then will settle down and be normal for awhile and feed off of everything in the tank.

It seems that the day before I have one die that I notice one that isnt doing much....just sits on the bottom real still for awhile then might feed for a second then settle back down to doing nothing.

 

[southpaw]

I will also ask the LFS what there water parameters are and see how different their's is to mine.....also if they have had alot of problems with this batch.

When I replaced the last two I noticed they didnt have hardly any left in the tanks like they did 3 days before when i got mine....hope this was due to selling alot and not due to deaths.

 

[Carp37]

Mine seem to have hyper periods at time running up and down the glass in packs of two or three but then will settle down and be normal for awhile and feed off of everything in the tank

Don't worry about that too much unless they're really frequently taking air at the surface (they should be doing that periodically anyway, but not every couple of minutes); Corys will run up the glass in groups anyway, especially if they're in a new tank- they should have really busy periods and periods of settling down for a rest, and lots of snuffling about for food.

I'm assuming there's no salt in the water? Some types can't tolerate salt very well, others are OK.

 

[southpaw]

No salt...

Just noticed I have another one sitting real still....watched hm surface for air then went right back to sitting on the bottom...I will keep an eye out on him the rest of the day.