I lost my red blue orchid rosetail halfmoon a few weeks ago to dropsy suddenly, was fine one day, had dropsy the next and had passed before I came home from work. I did a 90% water change and rearranged the tank. I ordered a marbled halfmoon plakat and he’s probably the prettiest betta I ever had gotten. Not sure why I been having bad luck with bettas lately, my king and salamander butterfly halfmoon bettas are thriving, while others get sick only do die shortly after.