Sad day at my house. One of my goldfishes died this morning of Swimbladder Disease. Its partner is still alive and seemingly healthy. I'll keep a close eye on his health.
Swimbladder disease can be a result of several things. So exact cause of death is uncertain. Water was cleaned and fresh. I changed it again last night when I saw it was swimming sideways. I gave it pea skins last as per recommended by various online fish health articles.
First 2 weeks in a new place are always tough. I am sorry that it did not last that period. I am sad to see it go.