my only Grrlie had her ventral ripped off by 'Da Big, Vishus Donny' back when i was just starting with Bettas.
wash everything! i found a good way to nuke a tank is Vinegar. give the entire thing a vinegar bath. i did this after Lil Phoenix (an Ick+Fungus boy) died, then i put Pierce in. it's been two weeks without incident, so i think it works well. not sure if it kills bacteria though, but Dropsy is very contagious and everything should be washed very thoroughly!