i have 2 55 gallon aquariums i started out with 15 cories and have averaged one a day for the past 6 days i have done water changes bi weekly and treated with stress coat everytime. i thought maybe it was my duck weed so i netted 98% of it , but they are still dieing! and it happens within an hour, they will be swimming then BAM!!! there on the bottom twitching, any ideals? its only the albino cories that are being affected. my emerald cories are doing good, (knock on wood).