[Studman0143]

Two months ago I bought 3 Metae (Bandit) Cory's. They sat in a QT (55G) with 9 other fish for 5 weeks. Upon putting them in their new home (29G), the were all dead within a week (which was 2 weeks ago). I can't seem to pinpoint why either.

Tank Setup:
Moderately planted. 2/3 of the tank has a typical plant substrate, the other 1/3 is fine sand. There are three large pieces of lace rock on one side. The other fish are 7 asian rummynose and 2 long finned black skirt tetras.

Feedings happened 2-3x/week. During that one week they were alive in the new tank, I only fed flake food and wafers. I know some of flakes made it to the bottom of the tank and the wafers obviously did.

The water quality was fine all week and all the other fish are still alive and healthy. So what killed them? I'm sure lack of food could be a possibility, but seems odd because they were on the same feeding schedule & diet in the QT. Could the lace rock have been damaging to their bodies in some form? Or the switch to a smaller tank stressful?

Any thoughts would be helpful. Thanks.

 

[bcarrot]

Do you know what the pH was in the 55g compared to the 29g?

Did you slowly acclimate them, or did you just move them directly from one tank to another?

When you say "water quality was fine", do you mean Ammonia and Nitrites were 0ppm and Nitrates were low? Just wanted to clarify. "Fine" can mean different things to different people

 

[Coralbandit]

Besides medical confinement another function of the QT is to acclimate new fish to "our" water.
If they were going in a tank with lace rock they should have had matching water in the QT(some lace rock?).
Cories really do not do well in "hard" water.
I'm betting the lace rock is what did them in.
Actually the GH,KH,ph swing.
The cories are know to be sensitive to salt and often salt(sodium chloride) is one of the main components of "hard "water.
Just my quick guess?