That's the only way to put it.They're just fading away.
Symptoms;They lose all energy and appetite and just sit in one spot getting weaker until they die.This may take up to a week .I've lost two and one is going and another just started.They are not old enough for ot to be old age.
Water parameters are all good.ph 7.0,nitrates and nitrites are at less than 1.0ppm,ammonia is 0.Gh is soft.Water temp is average of mid 70's.
HELP!!!!Please.

I also have Zebra Danios in the same tank and they are fine.

nitrites are at less than 1.0ppm << not good should be 0ppm try adding a little salt maybe 1 teaspoon per 20 gallons should help with nitrite poisoning.

Due to problems with my ISP this is the first time I could get back.Nitrates are now zero'ed.But fish don't show signs of classic nitrate/nitrite poisoning.I think I'm dealing with a swim bladder infection.Strange that it's only affecting the corys.I've only got one left that can swim to the top.Two are on the bottom sick and three have died. :rip:

Goodnews,kinda.After several water changes,total filter cleaning and replacement of cartridge,isolation and subsequent deaths of ill fish,the sole remaining cory seems to be doing well.
Why couldn't it have been that damned cat?